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du Pasquier J, Paës G, Perré P. Principal factors affecting the yield of dilute acid pretreatment of lignocellulosic biomass: A critical review. BIORESOURCE TECHNOLOGY 2023; 369:128439. [PMID: 36493953 DOI: 10.1016/j.biortech.2022.128439] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Revised: 11/30/2022] [Accepted: 12/01/2022] [Indexed: 06/17/2023]
Abstract
This review provides a critical analysis of the state of the art of dilute acid pretreatment applied to lignocellulosic biomass. Data from 63 publications were extracted and analysed. The majority of the papers used residence times of<30 min, temperature ranges from 100 °C to 200 °C, and acid levels between 0 % and 2 %. Yields are quantified directly after pretreatment (xylose content) or after enzymatic hydrolysis (glucose content). Statistical analyses allowed the time-temperature equivalence to be quantified for three types of biomass: they were formulated by non-linear expressions. In further works, investigating less explored areas, for example moderate temperature levels with longer residence times, is recommended. Pretreatment material (time-temperature kinetics, reactor type) and analytical methods should be standardized and better described. It becomes mandatory to promote the development of an open, findable, accessible, interoperable, and reusable data approach for pretreatments research.
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Affiliation(s)
- Julien du Pasquier
- Université de Reims Champagne Ardenne, INRAE, FARE, UMR A 614, 51100 Reims, France; Université Paris-Saclay, CentraleSupélec, Laboratoire de Génie des Procédés et Matériaux, Centre Européen de Biotechnologie et de Bioéconomie (CEBB), 51110 Pomacle, France
| | - Gabriel Paës
- Université de Reims Champagne Ardenne, INRAE, FARE, UMR A 614, 51100 Reims, France.
| | - Patrick Perré
- Université Paris-Saclay, CentraleSupélec, Laboratoire de Génie des Procédés et Matériaux, Centre Européen de Biotechnologie et de Bioéconomie (CEBB), 51110 Pomacle, France
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Maltari R, Kontro J, Koivu K, Farooq M, Mikkilä J, Zhang R, Hildén K, Sipilä J, Nousiainen PA. Fractionation of Technical Lignin from Enzymatically Treated Steam-Exploded Poplar Using Ethanol and Formic Acid. ACS APPLIED POLYMER MATERIALS 2022; 4:9388-9398. [PMID: 36532889 PMCID: PMC9748740 DOI: 10.1021/acsapm.2c01665] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Accepted: 11/11/2022] [Indexed: 06/01/2023]
Abstract
Lignocellulosic biorefineries produce lignin-rich side streams with high valorization potential concealed behind their recalcitrant structure. Valorization of these residues to chemicals, materials, and fuels increases the profitability of biorefineries. Fractionation is required to reduce the lignins' structural heterogeneity for further processing. We fractionated the technical biorefinery lignin received after steam explosion and saccharification processes. More homogeneous lignin fractions were produced with high β-O-4' and aromatic content without residual carbohydrates. Non-toxic biodegradable organic solvents like ethanol and formic acid were used for fractionation and can be adapted to the existing biorefinery processes. Macromolecular properties of the isolated fractions were carefully characterized by structural, chemical, and thermal methods. The ethanol organosolv treatment produced highly soluble lignin with a reasonable yield, providing a uniform material for lignin applications. The organosolv fractionation with formic acid and combined ethanol-formic acid produced modified lignins that, based on thermal analysis, are promising as thermoresponsive materials.
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Affiliation(s)
- Riku Maltari
- Department
of Chemistry, University of Helsinki, P.O. Box 55, A. I. Virtasen Aukio
1, Helsinki FI-00014, Finland
- Department
of Microbiology, University of Helsinki, P.O. Box 56, Viikinkaari 9, Helsinki FI-00014, Finland
| | - Jussi Kontro
- Department
of Chemistry, University of Helsinki, P.O. Box 55, A. I. Virtasen Aukio
1, Helsinki FI-00014, Finland
| | - Klaus Koivu
- Department
of Chemistry, University of Helsinki, P.O. Box 55, A. I. Virtasen Aukio
1, Helsinki FI-00014, Finland
| | - Muhammad Farooq
- Department
of Bioproducts and Biosystems, Aalto University, Vuorimiehentie 1, Espoo FI-02150, Finland
| | - Joona Mikkilä
- Department
of Chemistry, University of Helsinki, P.O. Box 55, A. I. Virtasen Aukio
1, Helsinki FI-00014, Finland
- Department
of Microbiology, University of Helsinki, P.O. Box 56, Viikinkaari 9, Helsinki FI-00014, Finland
| | - Rui Zhang
- Department
of Chemistry, University of Helsinki, P.O. Box 55, A. I. Virtasen Aukio
1, Helsinki FI-00014, Finland
| | - Kristiina Hildén
- Department
of Microbiology, University of Helsinki, P.O. Box 56, Viikinkaari 9, Helsinki FI-00014, Finland
| | - Jussi Sipilä
- Department
of Chemistry, University of Helsinki, P.O. Box 55, A. I. Virtasen Aukio
1, Helsinki FI-00014, Finland
| | - Paula A. Nousiainen
- Department
of Chemistry, University of Helsinki, P.O. Box 55, A. I. Virtasen Aukio
1, Helsinki FI-00014, Finland
- Department
of Bioproducts and Biosystems, Aalto University, Vuorimiehentie 1, Espoo FI-02150, Finland
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Zhai R, Hu J, Jin M. Towards efficient enzymatic saccharification of pretreated lignocellulose: Enzyme inhibition by lignin-derived phenolics and recent trends in mitigation strategies. Biotechnol Adv 2022; 61:108044. [PMID: 36152893 DOI: 10.1016/j.biotechadv.2022.108044] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Revised: 08/24/2022] [Accepted: 09/19/2022] [Indexed: 01/01/2023]
Abstract
Lignocellulosic biorefinery based on its sugar-platform has been considered as an efficient strategy to replace fossil fuel-based refinery. In the bioconversion process, pretreatment is an essential step to firstly open up lignocellulose cell wall structure and enhance the accessibility of carbohydrates to hydrolytic enzymes. However, various lignin and/or carbohydrates degradation products (e.g. phenolics, 5-hydroxymethylfurfural, furfural) also generated during pretreatment, which severely inhibit the following enzymatic hydrolysis and the downstream fermentation process. Among them, the lignin derived phenolics have been considered as the most inhibitory compounds and their inhibitory effects are highly dependent on the source of biomass and the type of pretreatment strategy. Although liquid-solid separation and subsequent washing can remove the lignin derived phenolics and other inhibitors, this is undesirable in the realistic industrial application where the whole slurry of pretreated biomass need to be directly used in the hydrolysis process. This review summarizes the phenolics formation mechanism for various commonly applied pretreatment methods and discusses the key factors that affect the inhibitory effect of phenolics on cellulose hydrolysis. In addition, the recent achievements on the rational design of inhibition mitigation strategies to boost cellulose hydrolysis for sugar-platform biorefinery are also introduced. This review also provides guidance for rational design detoxification strategies to facilitate whole slurry hydrolysis which helps to realize the industrialization of lignocellulose biorefinery.
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Affiliation(s)
- Rui Zhai
- School of Environmental and Biological Engineering, Nanjing University of Science and Technology, 200 Xiaolingwei Street, Nanjing 210094, China
| | - Jianguang Hu
- Department of Chemical and Petroleum Engineering, University of Calgary, Calgary T2N 1N4, Canada
| | - Mingjie Jin
- School of Environmental and Biological Engineering, Nanjing University of Science and Technology, 200 Xiaolingwei Street, Nanjing 210094, China.
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Conversion of Waste Corn Straw to Value-Added Fuel via Hydrothermal Carbonization after Acid Washing. ENERGIES 2022. [DOI: 10.3390/en15051828] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
To enhance the hydrothermal carbonization (HTC) process on biomass waste and improve the quality of biomass solid fuel. Corn straw was pretreated with acid washing and subsequently hydrothermally carbonized at 180–270 °C. The solid product obtained (hydrochars) was compared with the solid product produced from untreated hydrothermally carbonized straw. The results show that the acid pretreatment removed 7.9% of the ash from the straw. ICP and XRD analysis show that most of the alkali and alkaline earth metals have been removed. This addresses the defect of high ash content as the HTC temperature increases. The HHV of hydrochars produced by HTC after acid washing can reach 27.7 MJ/kg, which is nearly 10% higher than that of hydrochars prepared without acid washing pretreatment, and nearly 70% higher than that of straw raw materials. Elemental analysis and FTIR analysis show that the acid washing pretreatment changed the content and structure of the biomass components in the straw, resulting in a more complete HTC reaction and higher carbon sequestration. The decrease of H/C and O/C deepened the degree of coal-like transformation of hydrochars, with the lowest approaching the bituminous coal zone. The combustion characteristics of the hydrochars prepared after acid washing were significantly upgraded, the comprehensive combustion index and thermal stability of hydrochars both increased. Therefore, HTC after acid washing pretreatment is beneficial to further improve the high heating value and combustion characteristics of hydrochar.
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Sheng Y, Xu Y. Nuclear magnetic resonance analysis of ascorbic acid assisted lignocellulose decomposition in dilute acid pretreatment and its stimulation on enzymatic hydrolysis. BIORESOURCE TECHNOLOGY 2022; 343:126147. [PMID: 34673187 DOI: 10.1016/j.biortech.2021.126147] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2021] [Revised: 09/08/2021] [Accepted: 09/10/2021] [Indexed: 06/13/2023]
Abstract
The effect of ascorbic acid addition on lignin decomposition in the dilute acid pretreatment and the corresponding cellulose conversion of pretreated biomass have been studied. This enhancement by ascorbic acid addition was dose dependent. Decomposed and residual bulk lignins from pretreated poplar were analyzed by 2D HSQC and 31P NMR spectra. The promotional effect on lignocellulose decomposition with the assistance of ascorbic acid addition was supported by the NMR analysis. The analysis showed that the addition of ascorbic acid has a more significant stimulation on decomposed lignins compared to residual bulk lignins. The stimulatory effect of ascorbic acid in lignocellulose decomposition benefits the cellulose conversion of the corresponding pretreated materials. Poplar pretreatment assisted with ascorbic acid (2-8% w/w) increased the final hydrolysis yield by 7.5%-32.2%. This promotional effect of ascorbic acid on enzyme digestibility was more obvious with higher enzyme loading.
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Affiliation(s)
- Yequan Sheng
- Key Laboratory of Forestry Genetics & Biotechnology, Nanjing Forestry University, Ministry of Education, Nanjing 210037, China; Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, College of Chemical Engineering, Nanjing Forestry University, Nanjing 210037, China; Jiangsu Province Key Laboratory of Green Biomass-based Fuels and Chemicals, Nanjing 210037, China
| | - Yong Xu
- Key Laboratory of Forestry Genetics & Biotechnology, Nanjing Forestry University, Ministry of Education, Nanjing 210037, China; Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, College of Chemical Engineering, Nanjing Forestry University, Nanjing 210037, China; Jiangsu Province Key Laboratory of Green Biomass-based Fuels and Chemicals, Nanjing 210037, China.
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Narisetty V, Cox R, Bommareddy R, Agrawal D, Ahmad E, Pant KK, Chandel AK, Bhatia SK, Kumar D, Binod P, Gupta VK, Kumar V. Valorisation of xylose to renewable fuels and chemicals, an essential step in augmenting the commercial viability of lignocellulosic biorefineries. SUSTAINABLE ENERGY & FUELS 2021; 6:29-65. [PMID: 35028420 PMCID: PMC8691124 DOI: 10.1039/d1se00927c] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Accepted: 10/25/2021] [Indexed: 05/30/2023]
Abstract
Biologists and engineers are making tremendous efforts in contributing to a sustainable and green society. To that end, there is growing interest in waste management and valorisation. Lignocellulosic biomass (LCB) is the most abundant material on the earth and an inevitable waste predominantly originating from agricultural residues, forest biomass and municipal solid waste streams. LCB serves as the renewable feedstock for clean and sustainable processes and products with low carbon emission. Cellulose and hemicellulose constitute the polymeric structure of LCB, which on depolymerisation liberates oligomeric or monomeric glucose and xylose, respectively. The preferential utilization of glucose and/or absence of the xylose metabolic pathway in microbial systems cause xylose valorization to be alienated and abandoned, a major bottleneck in the commercial viability of LCB-based biorefineries. Xylose is the second most abundant sugar in LCB, but a non-conventional industrial substrate unlike glucose. The current review seeks to summarize the recent developments in the biological conversion of xylose into a myriad of sustainable products and associated challenges. The review discusses the microbiology, genetics, and biochemistry of xylose metabolism with hurdles requiring debottlenecking for efficient xylose assimilation. It further describes the product formation by microbial cell factories which can assimilate xylose naturally and rewiring of metabolic networks to ameliorate xylose-based bioproduction in native as well as non-native strains. The review also includes a case study that provides an argument on a suitable pathway for optimal cell growth and succinic acid (SA) production from xylose through elementary flux mode analysis. Finally, a product portfolio from xylose bioconversion has been evaluated along with significant developments made through enzyme, metabolic and process engineering approaches, to maximize the product titers and yield, eventually empowering LCB-based biorefineries. Towards the end, the review is wrapped up with current challenges, concluding remarks, and prospects with an argument for intense future research into xylose-based biorefineries.
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Affiliation(s)
- Vivek Narisetty
- School of Water, Energy and Environment, Cranfield University Cranfield MK43 0AL UK +44 (0)1234754786
| | - Rylan Cox
- School of Water, Energy and Environment, Cranfield University Cranfield MK43 0AL UK +44 (0)1234754786
- School of Aerospace, Transport and Manufacturing, Cranfield University Cranfield MK43 0AL UK
| | - Rajesh Bommareddy
- Department of Applied Sciences, Northumbria University Newcastle upon Tyne NE1 8ST UK
| | - Deepti Agrawal
- Biochemistry and Biotechnology Area, Material Resource Efficiency Division, CSIR- Indian Institute of Petroleum Mohkampur Dehradun 248005 India
| | - Ejaz Ahmad
- Department of Chemical Engineering, Indian Institute of Technology (ISM) Dhanbad 826004 India
| | - Kamal Kumar Pant
- Department of Chemical Engineering, Indian Institute of Technology Delhi New Delhi 110016 India
| | - Anuj Kumar Chandel
- Department of Biotechnology, Engineering School of Lorena (EEL), University of São Paulo Lorena 12.602.810 Brazil
| | - Shashi Kant Bhatia
- Department of Biological Engineering, College of Engineering, Konkuk University Seoul 05029 Republic of Korea
| | - Dinesh Kumar
- School of Bioengineering & Food Technology, Shoolini University of Biotechnology and Management Sciences Solan 173229 Himachal Pradesh India
| | - Parmeswaran Binod
- Microbial Processes and Technology Division, CSIR-National Institute for Interdisciplinary Science and Technology (CSIR-NIIST) Thiruvananthapuram 695 019 Kerala India
| | | | - Vinod Kumar
- School of Water, Energy and Environment, Cranfield University Cranfield MK43 0AL UK +44 (0)1234754786
- Department of Chemical Engineering, Indian Institute of Technology Delhi New Delhi 110016 India
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Fractionation of Birch Wood by Integrating Alkaline-Acid Treatments and Hydrogenation in Ethanol over a Bifunctional Ruthenium Catalyst. Catalysts 2021. [DOI: 10.3390/catal11111362] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
For the first time, the fractionation of birch wood into microcrystalline cellulose, xylose and methoxyphenols is suggested based on the integration of alkali-acid pretreatments and hydrogenation in ethanol over a bifunctional Ru/C catalyst. It is established that removal of hemicelluloses during pretreatments of birch wood influences the yields of the liquid, gaseous and solid products of the non-catalytic and catalytic hydrogenation of pretreated samples in ethanol at 225 °C. The bifunctional Ru/carbon catalyst affects in different ways the conversion and yields of products of hydrogenation of the initial and acid- and alkali-pretreated birch wood. The most noticeable influence is characteristic of the hydrogenation of the acid-pretreated wood, where in contrast to the non-catalytic hydrogenation, the wood conversion and the yields of liquid products increase but the yields of the solid and gaseous products decrease. GC-MS, gel permeation chromatography and elemental analysis were used for characterization of the liquid product composition. The molecular mass distribution of the liquid products of hydrogenation of the initial and pretreated wood shifts towards the low-molecular range in the presence of the catalyst. From the GC-MS data, the contents of monomer compounds, predominantly 4-propylsyringol and 4-propanolsyringol, increase in the presence of the ruthenium catalyst. The solid products of catalytic hydrogenation of the pretreated wood contain up to 95 wt% of cellulose with the structure, similar to that of microcrystalline cellulose.
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Liu L, Sim SF, Lin S, Wan J, Zhang W, Li Q, Peng C. Integrated structural and chemical analyses for HCl-supported hydrochar and their adsorption mechanisms for aqueous sulfachloropyridazine removal. JOURNAL OF HAZARDOUS MATERIALS 2021; 417:126009. [PMID: 34229376 DOI: 10.1016/j.jhazmat.2021.126009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2021] [Revised: 04/09/2021] [Accepted: 04/24/2021] [Indexed: 06/13/2023]
Abstract
In this study, various HCl-supported hydrochar made from root powder of long-root Eichhornia crassipes were applied to adsorb aqueous sulfachloropyridazine (SCP). Adsorption capacity (qe μg g-1) was positively correlated with combined severity-CS. With CS increasing, carbonization degree, hydrophobicity, porosity and isoelectric point of hydrochar increased, but content of polar functional groups decreased. Hydrophobic interaction was important for SCP adsorption. A 24 × 36 peak area table was generated from 24 FT-IR absorbance spectra computed by peak detection algorithm. Afterwards, correlation analysis between qe μg g-1 and FT-IR peak area were conducted, indicating that wavenumbers at 555.4, 1227.47, 1374.51, 1604.5, 2901.4/2919.2 and 3514.63 cm-1 were helpful for SCP adsorption. Further, multivariate linear regression analyses showed that aromatic skeleton and phenolic hydroxyl were the two biggest contributors. Electrostatic attraction did not exist during the SCP adsorption process. Under strong acid condition, protonated amino groups in cationic SCP acting as a hydrogen donator interacted with electron-rich functional groups onto hydrochar by Hydrogen interaction. Under weak acid condition, neutral SCP served as an π electron donor to bond with hydrochar by π-π electron donator-acceptor interaction. This work could guide the functional groups modification strategy of hydrochar to make better use of it in water purification field.
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Affiliation(s)
- Lin Liu
- State Environmental Protection Key Laboratory of Environmental Risk Assessment and Control on Chemical Process, School of Resource and Environmental Engineering, East China University of Science and Technology, Shanghai 200237, China
| | - Siong Fong Sim
- University Malaysia Sarawak, Faculty of Resource Science and Technology, 94300 Kota Samarahan, Sarawak, Malaysia
| | - Sen Lin
- State Environmental Protection Key Laboratory of Environmental Risk Assessment and Control on Chemical Process, School of Resource and Environmental Engineering, East China University of Science and Technology, Shanghai 200237, China
| | - Jiang Wan
- State Environmental Protection Key Laboratory of Environmental Risk Assessment and Control on Chemical Process, School of Resource and Environmental Engineering, East China University of Science and Technology, Shanghai 200237, China
| | - Wei Zhang
- State Environmental Protection Key Laboratory of Environmental Risk Assessment and Control on Chemical Process, School of Resource and Environmental Engineering, East China University of Science and Technology, Shanghai 200237, China.
| | - Qiannan Li
- State Environmental Protection Key Laboratory of Environmental Risk Assessment and Control on Chemical Process, School of Resource and Environmental Engineering, East China University of Science and Technology, Shanghai 200237, China
| | - Cheng Peng
- State Environmental Protection Key Laboratory of Environmental Risk Assessment and Control on Chemical Process, School of Resource and Environmental Engineering, East China University of Science and Technology, Shanghai 200237, China.
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Pongchaiphol S, Chotirotsukon C, Raita M, Champreda V, Laosiripojana N. Two-Stage Fractionation of Sugarcane Bagasse by a Flow-through Hydrothermal/Ethanosolv Process. Ind Eng Chem Res 2021. [DOI: 10.1021/acs.iecr.1c00669] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Suchat Pongchaiphol
- The Joint Graduate School for Energy and Environment (JGSEE), King Mongkut’s University of Technology Thonburi, Prachauthit Road, Bangmod, Bangkok 10140, Thailand
- BIOTEC-JGSEE Integrative Biorefinery Laboratory, Innovation
Cluster 2 Building, Thailand Science Park, Paholyothin Road, Khlong Luang, Pathumthani 12120, Thailand
| | - Chayanon Chotirotsukon
- Biorefinery and Bioproduct Technology Research Group, National Center for Genetic Engineering and Biotechnology (BIOTEC), 113 Thailand Science Park, Paholyothin Road, Khlong Luang, Pathumthani 12120, Thailand
- BIOTEC-JGSEE Integrative Biorefinery Laboratory, Innovation
Cluster 2 Building, Thailand Science Park, Paholyothin Road, Khlong Luang, Pathumthani 12120, Thailand
| | - Marisa Raita
- The Joint Graduate School for Energy and Environment (JGSEE), King Mongkut’s University of Technology Thonburi, Prachauthit Road, Bangmod, Bangkok 10140, Thailand
- BIOTEC-JGSEE Integrative Biorefinery Laboratory, Innovation
Cluster 2 Building, Thailand Science Park, Paholyothin Road, Khlong Luang, Pathumthani 12120, Thailand
| | - Verawat Champreda
- Biorefinery and Bioproduct Technology Research Group, National Center for Genetic Engineering and Biotechnology (BIOTEC), 113 Thailand Science Park, Paholyothin Road, Khlong Luang, Pathumthani 12120, Thailand
- BIOTEC-JGSEE Integrative Biorefinery Laboratory, Innovation
Cluster 2 Building, Thailand Science Park, Paholyothin Road, Khlong Luang, Pathumthani 12120, Thailand
| | - Navadol Laosiripojana
- The Joint Graduate School for Energy and Environment (JGSEE), King Mongkut’s University of Technology Thonburi, Prachauthit Road, Bangmod, Bangkok 10140, Thailand
- BIOTEC-JGSEE Integrative Biorefinery Laboratory, Innovation
Cluster 2 Building, Thailand Science Park, Paholyothin Road, Khlong Luang, Pathumthani 12120, Thailand
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Reduction of lignin heterogeneity using aqueous two-phase system: A facile and universal "one-step-three-fractions" approach. Int J Biol Macromol 2021; 186:341-350. [PMID: 34252462 DOI: 10.1016/j.ijbiomac.2021.07.054] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Revised: 07/05/2021] [Accepted: 07/07/2021] [Indexed: 11/24/2022]
Abstract
As the most abundant aromatic biopolymer, lignin presents great potential to produce valuable materials and chemicals. However, its large-scale value-added application is still facing many practical challenges and one of them is the unstable properties caused by lignin heterogeneity. Herein, we developed a novel "one-step-three-fractions" fractionation strategy to reduce lignin heterogeneity using aqueous two-phase system (ATPS) composed of (NH4)2SO4 and ethanol. In contrast to conventional step-wise fractionation processes, the proposed process subdivided heterogeneous lignin into three homogeneous fractions in only one step: the first fraction (F1) dissolved in the ethanol-rich top layer; the second fraction (F2) dissolved in the salt-rich bottom layer and the last fraction (F3) insoluble in both two layers. F2 presented the lowest molecular weight followed by F1 while F3 showed the highest molecular weight. With the increase of molecular weight, the contents of guaiacyl unit and β-O-4 linkage increased while the content of hydrophilic groups (carboxyl and aromatic hydroxyl) decreased significantly. Moreover, the ATPS exhibited satisfactory recyclability and the fractionation approach could be applied to different types/sources of lignin. Consequently, the work indicates that ATPS is a novel and effective way to fractionate lignin and reduce its molecular weight polydispersity and structural heterogeneity in one step.
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Ntaikou I, Siankevich S, Lyberatos G. Effect of thermo-chemical pretreatment on the saccharification and enzymatic digestibility of olive mill stones and their bioconversion towards alcohols. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2021; 28:24570-24579. [PMID: 32557020 DOI: 10.1007/s11356-020-09625-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/30/2019] [Accepted: 06/04/2020] [Indexed: 06/11/2023]
Abstract
The present study investigated the effect of thermo-chemical pretreatment on the enhancement of enzymatic digestibility of olive mill stones (OMS), as well as its possible valorisation via bioconversion of the generated free sugars to alcohols. Specifically, the influence of parameters such as reaction time, temperature, type and concentration of dilute acids and/or bases, was assessed during the thermo-chemical pretreatment. The hydrolysates and the solids remaining after pretreatment, as well as the whole pretreated slurries, were further evaluated as potential substrates for the simultaneous production of ethanol and xylitol via fermentation with the yeast Pachysolen tannophilus. The digestibility and overall saccharification of OMS were considerably enhanced in all cases, with the maximum enzymatic digestibility observed for dilute sodium hydroxide (almost 4-fold) which also yielded the highest total saccharification yield (91% of the total OMS carbohydrates). Ethanol and xylitol yields from the untreated OMS were 28 g/kg OMS and 25 g/kg OMS, respectively, and were both significantly enhanced by pretreatment. The highest ethanol yield was 79 g/kg OMS and was achieved by the alkali pretreatment and separate fermentation of hydrolysates and solids, whereas the highest xylitol yield was 49 g/kg OMS and was obtained by pretreatment with sulphuric acid and separate fermentation of hydrolysates and solids.
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Affiliation(s)
- Ioanna Ntaikou
- Foundation for Research and Technology, Institute of Chemical Engineering Sciences, Stadiou 10, Platani, GR 50600, Patras, Greece.
| | - Sviatlana Siankevich
- Foundation for Research and Technology, Institute of Chemical Engineering Sciences, Stadiou 10, Platani, GR 50600, Patras, Greece
- Embion Technologies SA, Chemin de la Dent-d'Oche 1 A, Ecublens VD, 1024, Vaud, Switzerland
| | - Gerasimos Lyberatos
- Foundation for Research and Technology, Institute of Chemical Engineering Sciences, Stadiou 10, Platani, GR 50600, Patras, Greece
- School of Chemical Engineering Sciences, National Technical University of Athens, GR 15780, Athens, Greece
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Properties versus application requirements of solubilized lignins from an elm clone during different pre-treatments. Int J Biol Macromol 2021; 181:99-111. [PMID: 33757853 DOI: 10.1016/j.ijbiomac.2021.03.093] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2021] [Revised: 03/03/2021] [Accepted: 03/16/2021] [Indexed: 02/07/2023]
Abstract
Kraft pulping, organosolv process and acid hydrolysis were applied on an elm clone. The solubilized lignins were recovered and analyzed. Kraft pulping and acid hydrolysis led to lignins with higher phenolic OH content as result of extensive cleavage of β-O-4' linkages, as revealed by 13C solid state and 13C-1H heteronuclear single quantum coherence nuclear magnetic resonance. This depolymerization also yielded lower molecular weight lignins inferred by size exclusion chromatography. Contrarily, organosolv process gave rise to a lignin with a more preserved structure, maintaining a large number of β-O-4' linkages. Consequently, organosolv lignin presented lower phenolic OH content and higher molecular weight. Moreover, the high content of the labile native β-O-4' linkages in organosolv lignin resulted in a lower thermostability as compared to the kraft and acid lignins. On the other hand, the solubilized lignins from kraft and acid processes displayed an enrichment of S-units, whereas lignin from organosolv process was slightly enriched in G-units, containing all of them different native as well as pre-treatment derived units. These results could help to increase the inventory of lignin sources available for future lignin-based products, for which knowledge of the lignin properties versus application requirements is crucial.
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Abstract
The shortage of resources and increasing climate changes have brought the need for sustainable and renewable resources to people’s attention. Biomass is an earth-abundant material and has great potential as a feedstock for alternative fuels and chemicals. For the effective utilization of biomass, this biopolymer has to be depolymerized and transformed into key building blocks and/or the targeted products, and biological or chemical catalysts are commonly used for the rapid and energy-efficient reactions. This Special Issue introduces recent advances in the catalytic conversion of biomass into biofuels and value-added products.
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Production of Levulinic Acid from Cellulose and Cellulosic Biomass in Different Catalytic Systems. Catalysts 2020. [DOI: 10.3390/catal10091006] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The reasonable and effective use of lignocellulosic biomass is an important way to solve the current energy crisis. Cellulose is abundant in nature and can be hydrolyzed to a variety of important energy substances and platform compounds—for instance, glucose, 5-hydroxymethylfurfural (HMF), levulinic acid (LA), etc. As a chemical linker between biomass and petroleum processing, LA has become an ideal feedstock for the formation of liquid fuels. At present, some problems such as low yield, high equipment requirements, difficult separation, and serious environmental pollution in the production of LA from cellulose have still not been solved. Thus, a more efficient and green catalytic system of this process for industrial production is highly desired. Herein, we focus on the reaction mechanism, pretreatment, and catalytic systems of LA from cellulose and cellulosic biomass, and a series of existing technologies for producing LA are reviewed. On the other hand, the industrial production of LA is discussed in depth to improve the yield of LA and make the process economical and energy efficient. Additionally, practical suggestions for the enhancement of the stability and efficiency of the catalysts are also proposed. The use of cellulose to produce LA is consistent with the concept of sustainable development, and the dependence on fossil resources will be greatly reduced through the realization of this process route.
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15
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Liu X, Li T, Wu S, Ma H, Yin Y. Structural characterization and comparison of enzymatic and deep eutectic solvents isolated lignin from various green processes: Toward lignin valorization. BIORESOURCE TECHNOLOGY 2020; 310:123460. [PMID: 32402988 DOI: 10.1016/j.biortech.2020.123460] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2020] [Revised: 04/25/2020] [Accepted: 04/27/2020] [Indexed: 06/11/2023]
Abstract
In this work, several representative green processes were developed to extract the enzymatic lignin and deep eutectic solvents (DESs) isolated lignin from corn straw. The results revealed that enzymatic lignin and DESs isolated lignin had a relatively low and homogeneous molecular weight and DESs isolated lignin shown a higher purity. Enzymatic and DESs isolated lignin showed good representativeness and similar to original herbal lignin structures accompany few aryl ether linkage cleavages and oxidation phenomenon. Among them, the subcritical CO2-assisted autohydrolysis and ChCl/Lac DESs treatment exhibited a higher severity for lignin preparation, and sequence DESs isolated lignin had a better reactivity. The β-O-4 ether bonds and carbon-carbon bonds linkage were further broken up during the Lac and DESs sequence treatment. In short, the described processes showed practical significance for lignin extraction and potential valorization, as well as help to develop more novel strategies for the current biorefinery process.
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Affiliation(s)
- Xiao Liu
- State Key Laboratory of Pulp and Paper Engineering, South China University of Technology, Guangzhou 510640, PR China
| | - Tengfei Li
- State Key Laboratory of Pulp and Paper Engineering, South China University of Technology, Guangzhou 510640, PR China
| | - Shubin Wu
- State Key Laboratory of Pulp and Paper Engineering, South China University of Technology, Guangzhou 510640, PR China.
| | - Hao Ma
- State Key Laboratory of Pulp and Paper Engineering, South China University of Technology, Guangzhou 510640, PR China
| | - Yihui Yin
- State Key Laboratory of Pulp and Paper Engineering, South China University of Technology, Guangzhou 510640, PR China
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16
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Zhou M, Shi H, Li C, Sheng X, Sun Y, Hou M, Niu M, Pan X. Depolymerization and Activation of Alkali Lignin by Solid Acid-Catalyzed Phenolation for Preparation of Lignin-Based Phenolic Foams. Ind Eng Chem Res 2020. [DOI: 10.1021/acs.iecr.0c01753] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Miaofang Zhou
- Liaoning Key Laboratory of Pulp and Paper Engineering, Dalian Polytechnic University, Dalian 116034, China
| | - Haiqiang Shi
- Liaoning Key Laboratory of Pulp and Paper Engineering, Dalian Polytechnic University, Dalian 116034, China
- Department of Biological Systems Engineering, University of Wisconsin−Madison, Madison, Wisconsin 53706, United States
| | - Chao Li
- Liaoning Key Laboratory of Pulp and Paper Engineering, Dalian Polytechnic University, Dalian 116034, China
| | - Xueru Sheng
- Liaoning Key Laboratory of Pulp and Paper Engineering, Dalian Polytechnic University, Dalian 116034, China
| | - Yanning Sun
- Liaoning Key Laboratory of Pulp and Paper Engineering, Dalian Polytechnic University, Dalian 116034, China
| | - Minjie Hou
- Liaoning Key Laboratory of Pulp and Paper Engineering, Dalian Polytechnic University, Dalian 116034, China
| | - Meihong Niu
- Liaoning Key Laboratory of Pulp and Paper Engineering, Dalian Polytechnic University, Dalian 116034, China
| | - Xuejun Pan
- Department of Biological Systems Engineering, University of Wisconsin−Madison, Madison, Wisconsin 53706, United States
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17
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Xu L, Zhang SJ, Zhong C, Li BZ, Yuan YJ. Alkali-Based Pretreatment-Facilitated Lignin Valorization: A Review. Ind Eng Chem Res 2020. [DOI: 10.1021/acs.iecr.0c01456] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Li Xu
- Frontiers Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering (Ministry of Education), School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, P. R. China
- Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin University, Tianjin 300072, P. R. China
| | - Sen-Jia Zhang
- Key Laboratory of Industrial Fermentation Microbiology (Ministry of Education), Tianjin University of Science and Technology, Tianjin 300457, P. R. China
| | - Cheng Zhong
- Key Laboratory of Industrial Fermentation Microbiology (Ministry of Education), Tianjin University of Science and Technology, Tianjin 300457, P. R. China
| | - Bing-Zhi Li
- Frontiers Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering (Ministry of Education), School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, P. R. China
- Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin University, Tianjin 300072, P. R. China
| | - Ying-Jin Yuan
- Frontiers Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering (Ministry of Education), School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, P. R. China
- Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin University, Tianjin 300072, P. R. China
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18
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Xu Y, Wang P, Xue S, Kong F, Ren H, Zhai H. Green biorefinery - the ultra-high hydrolysis rate and behavior of Populus tomentosa hemicellulose autohydrolysis under moderate subcritical water conditions. RSC Adv 2020; 10:18908-18917. [PMID: 35518329 PMCID: PMC9053882 DOI: 10.1039/d0ra02350g] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Accepted: 05/11/2020] [Indexed: 11/23/2022] Open
Abstract
A high monosaccharide conversion rate of hemicellulose in a green solvent and under moderate reaction conditions for industrialization is one of the most important keys in a lignocellulosic biorefinery. The behavior of Populus tomentosa hemicellulose polysaccharides, crystallinity and the furfural formation in the autohydrolysis process under moderate subcritical water conditions (160-180 °C, 0.618-1.002 MPa) were studied. The results have shown that the hemicellulose was converted to corresponding monosaccharides at an ultra-high hydrolysis rate. Factor analysis indicates that the temperature is the most important factor affecting hemicellulose autohydrolysis. When the autohydrolysis temperature increased from 160 to 180 °C for 2 h, the hydrolysis rate of xylose, rhamnose, galactose, mannose, and glucose from hemicellulose increased from 70% to 91%, 71% to 100%, 82% to 95%, 42% to 58%, and 34% to 37%, respectively. Arabinose was completely dissolved in 30 min. The xylose, rhamnose, galactose, and arabinose from hemicellulose could be almost completely removed under the conditions. The hemicellulose removal rate obtained herein exceeded the values reported for most acid, alkali, ionic liquid, or deep eutectic solvent treatments. It is notable that almost all glucose in hemicellulose was dissolved and the glucose in cellulose was partially hydrolyzed. An analysis of the sugar composition and the crystallinity change in the process at 180 °C demonstrate that hydrolysis reaction started to shift from amorphous regions to crystalline regions, due to the partial hydrolysis of crystalline cellulose after 90 min at 180 °C. Overall, these results show that the moderate subcritical water autohydrolysis of hemicellulose in Populus tomentosa may be a potential bio-refinery process.
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Affiliation(s)
- Yanru Xu
- Jiangsu Provincial Key Lab of Pulp and Paper Science and Technology, NanJing Forestry University Address No. 159 LongPan Road NanJing JiangSu Province 210037 China
| | - Pengfei Wang
- Jiangsu Provincial Key Lab of Pulp and Paper Science and Technology, NanJing Forestry University Address No. 159 LongPan Road NanJing JiangSu Province 210037 China
| | - Shiwen Xue
- Jiangsu Provincial Key Lab of Pulp and Paper Science and Technology, NanJing Forestry University Address No. 159 LongPan Road NanJing JiangSu Province 210037 China
| | - Fangong Kong
- State Key Laboratory of Biobased Material and Green Papermaking, Qilu University of Technology, Shandong Academy of Sciences Jinan 250353 China
| | - Hao Ren
- Jiangsu Provincial Key Lab of Pulp and Paper Science and Technology, NanJing Forestry University Address No. 159 LongPan Road NanJing JiangSu Province 210037 China
- State Key Laboratory of Biobased Material and Green Papermaking, Qilu University of Technology, Shandong Academy of Sciences Jinan 250353 China
| | - Huamin Zhai
- Jiangsu Provincial Key Lab of Pulp and Paper Science and Technology, NanJing Forestry University Address No. 159 LongPan Road NanJing JiangSu Province 210037 China
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19
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Dutta S, Yu IKM, Tsang DCW, Su Z, Hu C, Wu KCW, Yip ACK, Ok YS, Poon CS. Influence of green solvent on levulinic acid production from lignocellulosic paper waste. BIORESOURCE TECHNOLOGY 2020; 298:122544. [PMID: 31838242 DOI: 10.1016/j.biortech.2019.122544] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Revised: 11/29/2019] [Accepted: 11/30/2019] [Indexed: 06/10/2023]
Abstract
Lignocellulosic wastes constitute a significant portion of the municipal solid waste, which should be valorised for the synthesis of value-added chemicals to achieve circular bioeconomy. This study evaluates the use of γ-valerolactone (GVL) and acetone as green co-solvents to produce levulinic acid (LA) from lignocellulosic paper towel waste at different temperatures using dilute H2SO4. At the highest reaction temperature (200 °C), H2O-only system achieved ~15 Cmol% of LA at maximum. while GVL/H2O and acetone/H2O co-solvent systems enhanced the depolymerisation of paper towel waste and the subsequent conversion to LA, with the highest yield amounted to ~32 Cmol%. Acetone/H2O solvent system generated ~17 Cmol% LA at a lower temperature (180 °C), while higher temperature induced polymerisation of soluble sugars and intermediates, hindering further conversion to LA. In contrast, the availability of soluble sugars was higher in the GVL/H2O system, which favoured the production of LA at higher temperatures.
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Affiliation(s)
- Shanta Dutta
- Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China
| | - Iris K M Yu
- Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China
| | - Daniel C W Tsang
- Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China.
| | - Zhishan Su
- Key Laboratory of Green Chemistry and Technology, Ministry of Education, College of Chemistry, Sichuan University, No. 29 Wangjiang Road, Chengdu, Sichuan 610064, China
| | - Changwei Hu
- Key Laboratory of Green Chemistry and Technology, Ministry of Education, College of Chemistry, Sichuan University, No. 29 Wangjiang Road, Chengdu, Sichuan 610064, China
| | - Kevin C W Wu
- Department of Chemical Engineering, National Taiwan University, Taipei 10617, Taiwan
| | - Alex C K Yip
- Energy and Environmental Catalysis Group, Department of Chemical and Process Engineering, University of Canterbury, Christchurch, New Zealand
| | - Yong Sik Ok
- Korea Biochar Research Center & Division of Environmental Science and Ecological Engineering, Korea University, Seoul, South Korea
| | - Chi Sun Poon
- Department of Civil and Environmental Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China
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20
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Yang H, Yoo CG, Meng X, Pu Y, Muchero W, Tuskan GA, Tschaplinski TJ, Ragauskas AJ, Yao L. Structural changes of lignins in natural Populus variants during different pretreatments. BIORESOURCE TECHNOLOGY 2020; 295:122240. [PMID: 31639629 DOI: 10.1016/j.biortech.2019.122240] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Revised: 09/30/2019] [Accepted: 10/02/2019] [Indexed: 06/10/2023]
Abstract
In the present study, three leading pretreatment technologies including dilute acid (DA), liquid hot water (LHW), and organosolv pretreatments (OS) were applied on two Populus natural variants with different recalcitrance. The structural features of the isolated lignins were analyzed accordingly. All the studied pretreatments reduced the molecular weights of the lignins. Aliphatic OH was reduced while phenolic OH was increased in all pretreated lignins. HSQC analysis revealed that pretreatment influenced the lignin composition and relative distribution of inter-unit linkages. The lignin S/G ratio was found to increase during DA pretreatment, while it was decreased after LHW and OS pretreatment. LHW pretreatment also resulted in much less cleavage of β-O-4 linkage than the other two pretreatments. These results could offer guidelines on appropriate selection of biomass and pretreatment technology in the future biorefinery process.
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Affiliation(s)
- Haitao Yang
- Hubei Provincial Key Laboratory of Green Materials for Light Industry, Hubei University of Technology, Wuhan 430068, China; Collaborative Innovation Center of Green Light-weight Materials and Processing, Hubei University of Technology, Wuhan 430068, China; Chemical and Biomolecular Engineering, University of Tennessee, Knoxville, TN 37996, USA
| | - Chang Geun Yoo
- Department of Paper and Bioprocess Engineering, State University of New York College of Environmental Science and Forestry, Syracuse, NY 13210, USA
| | - Xianzhi Meng
- Chemical and Biomolecular Engineering, University of Tennessee, Knoxville, TN 37996, USA
| | - Yunqiao Pu
- The Center for Bioenergy Innovation & BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Wellington Muchero
- The Center for Bioenergy Innovation & BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Gerald A Tuskan
- The Center for Bioenergy Innovation & BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Timothy J Tschaplinski
- The Center for Bioenergy Innovation & BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Arthur J Ragauskas
- Chemical and Biomolecular Engineering, University of Tennessee, Knoxville, TN 37996, USA; The Center for Bioenergy Innovation & BioEnergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA; Department of Forestry, Wildlife and Fisheries, Center for Renewable Carbon, The University of Tennessee Institute of Agriculture, Knoxville, TN 37996, USA
| | - Lan Yao
- Hubei Provincial Key Laboratory of Green Materials for Light Industry, Hubei University of Technology, Wuhan 430068, China; Collaborative Innovation Center of Green Light-weight Materials and Processing, Hubei University of Technology, Wuhan 430068, China; Chemical and Biomolecular Engineering, University of Tennessee, Knoxville, TN 37996, USA.
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21
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Zhurka M, Spyridonidis A, Vasiliadou IA, Stamatelatou K. Biogas Production from Sunflower Head and Stalk Residues: Effect of Alkaline Pretreatment. Molecules 2019; 25:molecules25010164. [PMID: 31906116 PMCID: PMC6982727 DOI: 10.3390/molecules25010164] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2019] [Revised: 12/21/2019] [Accepted: 12/25/2019] [Indexed: 11/16/2022] Open
Abstract
Sunflower residues are considered a prominent renewable source for biogas production during anaerobic digestion (AD). However; the recalcitrant structure of this lignocellulosic substrate requires a pretreatment step for efficient biomass transformation and increased bioenergy output. The aim of the present study was to assess the effect of alkaline pretreatment of various parts of the sunflower residues (e.g., heads and stalks) on their methane yield. Experimental data showed that pretreatment at mild conditions (55 °C; 24 h; 4 g NaOH 100 g−1 total solids) caused an increase in the biochemical methane potential (BMP) of both heads and stalks of the sunflower residues as determined in batch tests. The highest methane production (268.35 ± 0.11 mL CH4 g−1 volatile solids) was achieved from the pretreated sunflower head residues. Thereafter; the effect of alkaline pretreatment of sunflower head residues was assessed in continuous mode; using continuous stirred-tank reactors (CSTRs) under two operational phases. During the first phase; the CSTRs were fed with the liquid fraction produced from the pretreatment of sunflower heads. During the second phase; the CSTRs were fed with the whole slurry resulting from the pretreatment of sunflower heads (i.e., both liquid and solid fractions). In both operating phases; it was observed that the alkaline pretreatment of the sunflower head residues had a negligible (phase I) or even a negative effect on biogas production; which was contradictory to the results of the BMP tests. It seems that; during alkaline pretreatment; this part of the sunflower residues (heads) may release inhibitory compounds; which induce a negative effect on biogas production in the long term (e.g., during continuously run digesters such as CSTR) but not in the short-term (e.g., batch tests) where the effect of the inoculum may not permit the inhibition to be established.
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22
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Zoghlami A, Refahi Y, Terryn C, Paës G. Multimodal characterization of acid-pretreated poplar reveals spectral and structural parameters strongly correlate with saccharification. BIORESOURCE TECHNOLOGY 2019; 293:122015. [PMID: 31454737 DOI: 10.1016/j.biortech.2019.122015] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2019] [Revised: 08/12/2019] [Accepted: 08/13/2019] [Indexed: 06/10/2023]
Abstract
Lignocellulose biomass can be transformed into sustainable chemicals, materials and energy but its natural recalcitrance requires the use of pretreatment to enhance subsequent catalytic steps. Dilute acid pretreatment is one of the most common and efficient ones, however its impact has not yet been investigated simultaneously at nano- and cellular-scales. Poplar samples have been pretreated by dilute acid at different controlled severities, then characterized by combined structural and spectral techniques (scanning electron microscopy, confocal microscopy, autofluorescence, fluorescence lifetime, Raman). Results show that pretreatment favours lignin depolymerization until severity of 2.4-2.5 while at severity of 2.7 lignin seems to repolymerize as revealed by broadening of autofluorescence spectrum and strong decrease in fluorescence lifetime. Importantly, both nano-scale and cellular-scale markers can predict hydrolysis yield of pretreated samples, highlighting some connections in the multiscale recalcitrance of lignocellulose.
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Affiliation(s)
- Aya Zoghlami
- FARE Laboratory, INRA, Université de Reims Champagne Ardenne, Reims, France
| | - Yassin Refahi
- FARE Laboratory, INRA, Université de Reims Champagne Ardenne, Reims, France
| | - Christine Terryn
- Platform of Cellular and Tissular Imaging (PICT), Université de Reims Champagne Ardenne, Reims, France
| | - Gabriel Paës
- FARE Laboratory, INRA, Université de Reims Champagne Ardenne, Reims, France.
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23
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Antonopoulou G, Kampranis A, Ntaikou I, Lyberatos G. Enhancement of Liquid and Gaseous Biofuels Production From Agro-Industrial Residues After Thermochemical and Enzymatic Pretreatment. FRONTIERS IN SUSTAINABLE FOOD SYSTEMS 2019. [DOI: 10.3389/fsufs.2019.00092] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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24
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Wan G, Zhang Q, Li M, Jia Z, Guo C, Luo B, Wang S, Min D. How Pseudo-lignin Is Generated during Dilute Sulfuric Acid Pretreatment. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2019; 67:10116-10125. [PMID: 31442037 DOI: 10.1021/acs.jafc.9b02851] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Pseudo-lignin is generated from lignocellulose biomass during pretreatment with dilute sulfuric acid and has a significant inhibitory effect on cellulase. However, the mechanism of pseudo-lignin generation remains unclear. The following main points have been addressed to help elucidate the pseudo-lignin generation pathway. Cellulose and xylan were pretreated with sulfuric acid at different concentrations; aliquots were periodically collected; and the changes in the byproducts of the prehydrolysate were quantified. Milled wood lignin (MWL) mixed with cellulose and xylan was pretreated to evaluate the impact of lignin on pseudo-lignin generation. Furfural, 5-hydroxymethylfurfural, and MWL were pretreated as model compounds to investigate pseudo-lignin generation. The result indicated that the increasing acid concentration significantly promoted the generation of pseudo-lignin. When the acid concentration was increased from 0 to 1.00 wt %, pseudo-lignin was increased from 1.36 to 4.05 g. In addition, lignin promoted the pseudo-lignin generation through the condensation between lignin and the generated intermediates.
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Affiliation(s)
- Guangcong Wan
- College of Light Industry and Food Engineering , Guangxi University , Nanning , Guangxi 530004 , People's Republic of China
- Guangxi Key Laboratory of Clean Pulp & Papermaking and Pollution Control , Nanning , Guangxi 530004 , People's Republic of China
| | - Qingtong Zhang
- College of Light Industry and Food Engineering , Guangxi University , Nanning , Guangxi 530004 , People's Republic of China
- Guangxi Key Laboratory of Clean Pulp & Papermaking and Pollution Control , Nanning , Guangxi 530004 , People's Republic of China
| | - Mingfu Li
- College of Light Industry and Food Engineering , Guangxi University , Nanning , Guangxi 530004 , People's Republic of China
- Guangxi Key Laboratory of Clean Pulp & Papermaking and Pollution Control , Nanning , Guangxi 530004 , People's Republic of China
| | - Zhuan Jia
- College of Light Industry and Food Engineering , Guangxi University , Nanning , Guangxi 530004 , People's Republic of China
- Guangxi Key Laboratory of Clean Pulp & Papermaking and Pollution Control , Nanning , Guangxi 530004 , People's Republic of China
| | - Chenyan Guo
- College of Light Industry and Food Engineering , Guangxi University , Nanning , Guangxi 530004 , People's Republic of China
- Guangxi Key Laboratory of Clean Pulp & Papermaking and Pollution Control , Nanning , Guangxi 530004 , People's Republic of China
| | - Bin Luo
- College of Light Industry and Food Engineering , Guangxi University , Nanning , Guangxi 530004 , People's Republic of China
- Guangxi Key Laboratory of Clean Pulp & Papermaking and Pollution Control , Nanning , Guangxi 530004 , People's Republic of China
| | - Shuangfei Wang
- College of Light Industry and Food Engineering , Guangxi University , Nanning , Guangxi 530004 , People's Republic of China
- Guangxi Key Laboratory of Clean Pulp & Papermaking and Pollution Control , Nanning , Guangxi 530004 , People's Republic of China
| | - Douyong Min
- College of Light Industry and Food Engineering , Guangxi University , Nanning , Guangxi 530004 , People's Republic of China
- Guangxi Key Laboratory of Clean Pulp & Papermaking and Pollution Control , Nanning , Guangxi 530004 , People's Republic of China
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25
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Membrane Separation of the Base-Catalyzed Depolymerization of Black Liquor Retentate for Low-Molecular-Mass Compound Production. MEMBRANES 2019; 9:membranes9080102. [PMID: 31426318 PMCID: PMC6722839 DOI: 10.3390/membranes9080102] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/10/2019] [Revised: 08/05/2019] [Accepted: 08/12/2019] [Indexed: 11/25/2022]
Abstract
One way of valorizing the lignin waste stream from the pulp and paper industries is depolymerizing it into low-molecular-mass compounds (LMMC). However, a common problem in the depolymerization of Kraft lignin is the low yields of small aromatic molecules obtained. In the present work, the combination of the repeated depolymerization of lignin and the separation of LMMC from depolymerized lignin to upgrade them into value-added chemicals was studied. In so doing, we investigated the possibility of depolymerizing black liquor retentate (BLR). The base-catalyzed depolymerization of BLR was performed using a continuous flow reactor at 170–210 °C, with a 2 min residence time. The results obtained indicate that BLR can be depolymerized effectively under the experimental conditions. Depolymerized lignin LMMC can be successfully separated by a GR95PP membrane, and thus be protected from repolymerization. Through combining membrane filtration with base-catalyzed depolymerization, more than half of the lignin could be depolymerized into LMMC. Around 46 mg/g of lignin monomers (guaiacol, vanillin, acetovanillone, and acetosyringone), which can potentially be upgraded to high-valued chemicals, were produced. On the basis of our results, we suggest use of a recycling Kraft lignin depolymerization and filtration process for maximizing the production of LMMC under mild alkaline conditions.
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26
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Martín-Sampedro R, Santos JI, Eugenio ME, Wicklein B, Jiménez-López L, Ibarra D. Chemical and thermal analysis of lignin streams from Robinia pseudoacacia L. generated during organosolv and acid hydrolysis pre-treatments and subsequent enzymatic hydrolysis. Int J Biol Macromol 2019; 140:311-322. [PMID: 31408656 DOI: 10.1016/j.ijbiomac.2019.08.029] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2019] [Revised: 06/28/2019] [Accepted: 08/04/2019] [Indexed: 12/22/2022]
Abstract
Lignin streams produced in biorefineries are commonly used to obtain energy. In order to increase the competitiveness of this industry, new lignin valorization routes are necessary, for which a depth characterization of this biological macromolecule is essential. In this context, this study analyzed lignin streams of Robinia pseudoacacia L. generated during organosolv and acid hydrolysis pre-treatments and during the subsequent enzymatic hydrolysis. These lignins included dissolved lignins from pre-treatment liquors and saccharification lignins from pre-treated materials. Chemical composition and structural features were analyzed by analytical standard methods and Fourier Transform Infrared spectroscopy (FTIR), size exclusion chromatography (SEC), 13C solid state nuclear magnetic resonance (13C NMR) and 1H-13C two-dimensional nuclear magnetic resonance (2D NMR); while thermal characterization included thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). In general, all studied lignins contained a predominance of β-O-4' aryl ether linkages, followed by resinol (β-β') and phenylcoumaran (β-5'), with a predominance of syringyl over guaiacyl and hydroxyphenyl units. Nevertheless, the dissolved lignins revealed a removal of linkages, especially β-O-4', leading to an enrichment of phenolic groups. Moreover, high thermal stability and good thermoplasticity were characteristics of these lignins. Contrary, the saccharification lignins exhibited a more intact structure, but with an important remaining carbohydrates content.
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Affiliation(s)
| | - José I Santos
- General Services of Research SGIKER, University of the Basque Country (UPV/EHU), Edificio Joxe Mari Korta Avda. Tolosa 72, Donostia-San Sebastian 20018, Spain
| | - María E Eugenio
- INIA-CIFOR, Forestry Products Department, Ctra de la Coruña Km 7.5, Madrid 28040, Spain
| | - Bernd Wicklein
- Instituto de Ciencia de Materiales de Madrid (ICMM), Consejo Superior de Investigaciones Científicas (CSIC), Sor Juana Inés de la Cruz 3, Cantoblanco, Madrid 28049, Spain
| | - Laura Jiménez-López
- INIA-CIFOR, Forestry Products Department, Ctra de la Coruña Km 7.5, Madrid 28040, Spain
| | - David Ibarra
- INIA-CIFOR, Forestry Products Department, Ctra de la Coruña Km 7.5, Madrid 28040, Spain.
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Kellock M, Maaheimo H, Marjamaa K, Rahikainen J, Zhang H, Holopainen-Mantila U, Ralph J, Tamminen T, Felby C, Kruus K. Effect of hydrothermal pretreatment severity on lignin inhibition in enzymatic hydrolysis. BIORESOURCE TECHNOLOGY 2019; 280:303-312. [PMID: 30776657 DOI: 10.1016/j.biortech.2019.02.051] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Revised: 02/06/2019] [Accepted: 02/08/2019] [Indexed: 05/19/2023]
Abstract
Hydrothermal pretreatment is commonly used for enhancing enzymatic hydrolysis of lignocellulosics. Spruce and wheat straw were pretreated with increasing severity and lignin characteristics were analysed. The effect of enzymatically isolated lignin on the hydrolysis of Avicel and the adsorption of a cellobiohydrolase onto lignin was measured. Non-pretreated lignins had only a minor effect on Avicel hydrolysis. The structural changes in lignin accompanying hydrothermal pretreatment were associated with increased binding and inactivation of the cellulase on the lignin surface. The inhibitory effect was more pronounced in spruce than in wheat straw lignin. However, similar pretreatment severities caused similar levels of inhibition in Avicel hydrolysis for both biomass sources. The combined severity factor of the pretreatment correlated well with the inhibitory effect of lignin.
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Affiliation(s)
- Miriam Kellock
- VTT Technical Research Centre of Finland Ltd, P.O Box 1000, 02044 VTT, Finland.
| | - Hannu Maaheimo
- VTT Technical Research Centre of Finland Ltd, P.O Box 1000, 02044 VTT, Finland.
| | - Kaisa Marjamaa
- VTT Technical Research Centre of Finland Ltd, P.O Box 1000, 02044 VTT, Finland.
| | - Jenni Rahikainen
- VTT Technical Research Centre of Finland Ltd, P.O Box 1000, 02044 VTT, Finland.
| | - Heng Zhang
- University of Copenhagen, Rolighedsvej 23, 1958 Frederiksberg C, Denmark.
| | | | - John Ralph
- University of Wisconsin, Madison, WI 53726, USA.
| | - Tarja Tamminen
- VTT Technical Research Centre of Finland Ltd, P.O Box 1000, 02044 VTT, Finland.
| | - Claus Felby
- University of Copenhagen, Rolighedsvej 23, 1958 Frederiksberg C, Denmark.
| | - Kristiina Kruus
- VTT Technical Research Centre of Finland Ltd, P.O Box 1000, 02044 VTT, Finland.
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28
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Chen D, Gao D, Capareda SC, Huang S, Wang Y. Effects of hydrochloric acid washing on the microstructure and pyrolysis bio-oil components of sweet sorghum bagasse. BIORESOURCE TECHNOLOGY 2019; 277:37-45. [PMID: 30658334 DOI: 10.1016/j.biortech.2019.01.023] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2018] [Revised: 01/06/2019] [Accepted: 01/07/2019] [Indexed: 05/09/2023]
Abstract
Acid washing is an alternative and promising approach for biomass to produce high-quality bio-oil. The hydrochloric acid washing pretreatment of sweet sorghum bagasse was performed in this study. The effects of acid washing on the ultrastructure of sweet sorghum bagasse were investigated using scanning electron microscope and Fourier transform infrared, and the effects on pyrolysis using thermogravimetric analyzer and a fast pyrolysis device. The results indicated acid treatment obviously changed the surface morphology of the cell walls of sweet sorghum bagasse, effectively removed most metals from sweet sorghum bagasse, and increased the volatiles and bio-oil yields. The results showed that bio-oil produced from pretreated sweet sorghum bagasse contained less components categories, lower contents of phenols, aldehydes, furans and alcohols, while much higher contents of d-allose and ketones than that from the original sample. Hydrochloric acid-washing pretreatment of sweet sorghum bagasse can increase the contents of some high-value chemicals in bio-oil.
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Affiliation(s)
- Dongyu Chen
- College of Engineering, Shenyang Agricultural University, Shenyang 110866, Liaoning, China
| | - Dongxiao Gao
- College of Engineering, Shenyang Agricultural University, Shenyang 110866, Liaoning, China
| | - Sergio C Capareda
- College of Agricultural and Life Science, Texas A & M University, College Station 77840, TX, USA
| | - Shunchao Huang
- College of Engineering, Shenyang Agricultural University, Shenyang 110866, Liaoning, China
| | - Ying Wang
- College of Engineering, Shenyang Agricultural University, Shenyang 110866, Liaoning, China
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29
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Wang H, Pu Y, Ragauskas A, Yang B. From lignin to valuable products-strategies, challenges, and prospects. BIORESOURCE TECHNOLOGY 2019; 271:449-461. [PMID: 30266464 DOI: 10.1016/j.biortech.2018.09.072] [Citation(s) in RCA: 245] [Impact Index Per Article: 49.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2018] [Revised: 09/13/2018] [Accepted: 09/14/2018] [Indexed: 05/24/2023]
Abstract
The exploration of effective approaches for the valorization of lignin to valuable products attracts broad interests of a growing scientific community. By fully unlocking the potential of the world's most abundant resource of bio-aromatics, it could improve the profitability and carbon efficiency of the entire biorefinery process, thus accelerate the replacement of fossil resources with bioresources in our society. The successful realization of this goal depends on the development of technologies to overcome the following challenges, including: 1) efficient biomass pretreatment and lignin separation technologies that overcomes its diverse structure and complex chemistry challenges to obtain high purity lignin; 2) advanced chemical analysis for precise quantitative characterization of the lignin in chemical transformation processes; 3) novel approaches for conversion of biomass-derived lignin to valuable products. This review summarizes the latest cutting-edge innovations of lignin chemical valorization with the focus on the aforementioned three key aspects.
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Affiliation(s)
- Hongliang Wang
- Bioproducts, Sciences, and Engineering Laboratory, Department of Biological Systems Engineering, Washington State University, Richland, WA 99354, USA; Center of Biomass Engineering/College of Agronomy and Biotechnology, China Agricultural University, Beijing 100193, China
| | - Yunqiao Pu
- Center for Bioenergy Innovation, Joint Institute of Biological Science, Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - Arthur Ragauskas
- Center for Bioenergy Innovation, Joint Institute of Biological Science, Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA; Department of Chemical and Biomolecular Engineering & Department of Forestry, Wildlife and Fisheries, Center for Renewable Carbon, University of Tennessee, Knoxville, TN, USA
| | - Bin Yang
- Bioproducts, Sciences, and Engineering Laboratory, Department of Biological Systems Engineering, Washington State University, Richland, WA 99354, USA; Earth and Biological Sciences Directorate, Pacific Northwest National Laboratory, Richland, WA 99352, USA.
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30
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Martín-Sampedro R, Santos JI, Fillat Ú, Wicklein B, Eugenio ME, Ibarra D. Characterization of lignins from Populus alba L. generated as by-products in different transformation processes: Kraft pulping, organosolv and acid hydrolysis. Int J Biol Macromol 2018; 126:18-29. [PMID: 30572057 DOI: 10.1016/j.ijbiomac.2018.12.158] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2018] [Revised: 12/11/2018] [Accepted: 12/17/2018] [Indexed: 11/28/2022]
Abstract
The complexity and heterogeneity of lignin requires a detailed understanding in order to decide about more efficient lignin valorization approaches. This study deals with the characterization of lignins from Populus alba L. generated as by-products in different transformation processes: kraft pulping, organosolv and dilute acid hydrolysis. In addition to the composition, the chemical and structural features of the different lignins were investigated by Fourier Transform infrared spectroscopy (FTIR), solid-state 13C nuclear magnetic resonance (13C NMR), two-dimensional nuclear magnetic spectrometry (2D NMR), size exclusion chromatography (SEC), and thermal analysis. Organosolv lignin showed noticeably different characteristics compared to kraft and acid hydrolysis lignins; higher molar mass, higher amount of side-chain linkages (mainly aryl-β ether and resinol) together with lower phenolic content. On the contrary, kraft and acid hydrolysis lignins presented an extensive elimination of lateral chains and therefore a higher phenolic content, which suggests a much stronger lignin depolymerization (lower molar mass) during these processes. Moreover, thermal analysis results revealed that the thermal stability of kraft and acid hydrolysis lignins was higher than that of organosolv lignin, especially in the case of acid hydrolysis lignin. According to all these characteristics, several valorization pathways for studied lignin are discussed.
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Affiliation(s)
| | - José I Santos
- General Services of Research SGIKER, University of the Basque Country (UPV/EHU), Edificio Joxe Mari Korta Avda. Tolosa 72, Donostia-San Sebastian 20018, Spain
| | - Úrsula Fillat
- INIA-CIFOR, Forestry Products Department, Ctra de la Coruña Km 7.5, Madrid 28040, Spain
| | - Bernd Wicklein
- Instituto de Ciencia de Materiales de Madrid (ICMM), Consejo Superior de Investigaciones Científicos (CSIC), Sor Juana Inés de la Cruz 3, Cantoblanco, Madrid 28049, Spain
| | - María E Eugenio
- INIA-CIFOR, Forestry Products Department, Ctra de la Coruña Km 7.5, Madrid 28040, Spain
| | - David Ibarra
- INIA-CIFOR, Forestry Products Department, Ctra de la Coruña Km 7.5, Madrid 28040, Spain.
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31
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Yao L, Yang H, Yoo CG, Pu Y, Meng X, Muchero W, Tuskan GA, Tschaplinski T, Ragauskas AJ. Understanding the influences of different pretreatments on recalcitrance of Populus natural variants. BIORESOURCE TECHNOLOGY 2018; 265:75-81. [PMID: 29883849 DOI: 10.1016/j.biortech.2018.05.057] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2018] [Revised: 05/15/2018] [Accepted: 05/16/2018] [Indexed: 06/08/2023]
Abstract
Four different pretreatment technologies were applied to two Populus natural variants and the effects of each pretreatment on glucose release were compared. Physicochemical properties of pretreated biomass were analyzed by attenuated total reflection Fourier transform infrared spectroscopy, gel permeation chromatography, and cross polarization/magic angle spinning carbon-13 nuclear magnetic resonance techniques. The results revealed that hemicellulose and lignin were removed to different extents during various pretreatments. The degree of polymerization of cellulose was decreased in the order of alkali > hydrothermal > organosolv > dilute acid pretreatment. Cellulose crystallinity index was slightly increased after each pretreatment. The results also demonstrated that organosolv pretreatment resulted in the highest glucose yield. Among the tested properties of Populus, degree of polymerization of cellulose was negatively correlated with glucose release, whereas hemicellulose and lignin removal, and cellulose accessibility were positively associated with glucose release from the two Populus natural variants.
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Affiliation(s)
- Lan Yao
- Hubei Provincial Key Laboratory of Green Materials for Light Industry, Hubei University of Technology, Wuhan 430068, China; Department of Chemical & Biomolecular Engineering, University of Tennessee Knoxville, Knoxville, TN 37996, USA
| | - Haitao Yang
- Hubei Provincial Key Laboratory of Green Materials for Light Industry, Hubei University of Technology, Wuhan 430068, China; Department of Chemical & Biomolecular Engineering, University of Tennessee Knoxville, Knoxville, TN 37996, USA
| | - Chang Geun Yoo
- The Center for Bioenergy Innovation & BioEnergy Science Center, Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Yunqiao Pu
- The Center for Bioenergy Innovation & BioEnergy Science Center, Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Xianzhi Meng
- Department of Chemical & Biomolecular Engineering, University of Tennessee Knoxville, Knoxville, TN 37996, USA
| | - Wellington Muchero
- The Center for Bioenergy Innovation & BioEnergy Science Center, Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Gerald A Tuskan
- The Center for Bioenergy Innovation & BioEnergy Science Center, Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Timothy Tschaplinski
- The Center for Bioenergy Innovation & BioEnergy Science Center, Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Arthur J Ragauskas
- Department of Chemical & Biomolecular Engineering, University of Tennessee Knoxville, Knoxville, TN 37996, USA; Department of Forestry, Wildlife and Fisheries, Center for Renewable Carbon, The University of Tennessee Knoxville, Institute of Agriculture, Knoxville, TN 37996, USA; The Center for Bioenergy Innovation & BioEnergy Science Center, Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA.
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32
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Jung S, Trajano HL, Yoo CG, Foston MB, Hu F, Tolbert AK, Wyman CE, Ragauskas AJ. Topochemical Understanding of Lignin Distribution During Hydrothermal Flowthrough Pretreatment. ChemistrySelect 2018. [DOI: 10.1002/slct.201801837] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Affiliation(s)
- Seokwon Jung
- School of Chemistry and Biochemistry; Georgia Institute of Technology, Atlanta; GA 30332 USA
- BioEnergy Science Center & Center for Bioenergy Innovation; Oak Ridge National Laboratory, Oak Ridge; TN 37831 USA
| | - Heather L. Trajano
- BioEnergy Science Center & Center for Bioenergy Innovation; Oak Ridge National Laboratory, Oak Ridge; TN 37831 USA
- Department of Chemical & Environmental Engineering; Center for Environmental Research and Technology University of California, Riverside; CA 92521 USA
- Department of Chemical and Biological Engineering; University of British Columbia Vancouver, British Columbia, V6T 1Z3; Canada
| | - Chang Geun Yoo
- BioEnergy Science Center & Center for Bioenergy Innovation; Oak Ridge National Laboratory, Oak Ridge; TN 37831 USA
- UT-ORNL Joint Institute for Biological Science; Oak Ridge National Laboratory, Oak Ridge; TN 37831 USA
| | - Marcus B. Foston
- BioEnergy Science Center & Center for Bioenergy Innovation; Oak Ridge National Laboratory, Oak Ridge; TN 37831 USA
- Department of Energy; Environmental & Chemical Engineering Washington University, Saint Louis; MO 63130 USA
| | - Fan Hu
- School of Chemistry and Biochemistry; Georgia Institute of Technology, Atlanta; GA 30332 USA
- BioEnergy Science Center & Center for Bioenergy Innovation; Oak Ridge National Laboratory, Oak Ridge; TN 37831 USA
| | - Allison K. Tolbert
- School of Chemistry and Biochemistry; Georgia Institute of Technology, Atlanta; GA 30332 USA
- BioEnergy Science Center & Center for Bioenergy Innovation; Oak Ridge National Laboratory, Oak Ridge; TN 37831 USA
| | - Charles E. Wyman
- BioEnergy Science Center & Center for Bioenergy Innovation; Oak Ridge National Laboratory, Oak Ridge; TN 37831 USA
- Department of Chemical & Environmental Engineering; Center for Environmental Research and Technology University of California, Riverside; CA 92521 USA
| | - Arthur J. Ragauskas
- School of Chemistry and Biochemistry; Georgia Institute of Technology, Atlanta; GA 30332 USA
- BioEnergy Science Center & Center for Bioenergy Innovation; Oak Ridge National Laboratory, Oak Ridge; TN 37831 USA
- UT-ORNL Joint Institute for Biological Science; Oak Ridge National Laboratory, Oak Ridge; TN 37831 USA
- Department of Chemical and Biomolecular Engineering & Department of Forestry, Wildlife; Fisheries University of Tennessee, Knoxville; TN 37996 USA
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33
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Jiang Z, Zhao P, Hu C. Controlling the cleavage of the inter- and intra-molecular linkages in lignocellulosic biomass for further biorefining: A review. BIORESOURCE TECHNOLOGY 2018; 256:466-477. [PMID: 29478782 DOI: 10.1016/j.biortech.2018.02.061] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Revised: 02/08/2018] [Accepted: 02/13/2018] [Indexed: 06/08/2023]
Abstract
The abundant intermolecular linkages among cellulose, hemicellulose and lignin significantly limit the utilization of the most promising renewable biomass. Process control with solvents, catalysts and temperature is of significant importance providing ways to break the above linkages, and benefiting to the further conversion of the main biomass components to small molecular products. This article discusses the effect of catalyst under hydrothermal and organosolv treatment emphasizing the cleavage of the intermolecular linkage. Acidic catalysts show good performance on cleaving the linkages between carbohydrates and lignin. Basic catalysts promoted the dissolution of lignin component. Hydrogenolysis assisted conversion of lignin can efficiently break the intermolecular linkages to yield lignin-derived bio-oil, especially in co-solvent reaction system. Besides, the effects of single solvent and co-solvent systems, as well as the cleavage of the intramolecular linkages to yield target chemicals are also included. Several further study strategies are proposed.
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Affiliation(s)
- Zhicheng Jiang
- Key Laboratory of Green Chemistry and Technology, Ministry of Education, College of Chemistry, Sichuan University, 29 Wangjiang Road, Chengdu, Sichuan, China
| | - Pingping Zhao
- Key Laboratory of Green Chemistry and Technology, Ministry of Education, College of Chemistry, Sichuan University, 29 Wangjiang Road, Chengdu, Sichuan, China
| | - Changwei Hu
- Key Laboratory of Green Chemistry and Technology, Ministry of Education, College of Chemistry, Sichuan University, 29 Wangjiang Road, Chengdu, Sichuan, China.
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Zhou X, Ding D, You T, Zhang X, Takabe K, Xu F. Synergetic Dissolution of Branched Xylan and Lignin Opens the Way for Enzymatic Hydrolysis of Poplar Cell Wall. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2018; 66:3449-3456. [PMID: 29553741 DOI: 10.1021/acs.jafc.8b00320] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
As the main hemicellulose of poplar, the interaction of xylan with lignin was expected to have profound effect on biomass recalcitrance. In this paper, the dynamic changes of xylan and lignin in poplar cell wall during a mild pretreatment using γ-valerolactone (GVL) was investigated using chemical and microscopic techniques. Synergetic dissolution of branched xylan and lignin from the secondary wall of the fiber cell was found to play a major role in opening the cell wall structure for enzymatic attack. In the case of the removal of xylan and lignin reaching a certain level, β-O-4' cleavage of lignin which destroyed its interaction with hydrophobic cellulose face was found to make great contribution to the enhanced enzymatic hydrolysis. The deep understanding of this process could lead to a new insight into the understanding of the plant cell wall architecture and provide basic information for biomass processing.
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Affiliation(s)
- Xia Zhou
- Beijing Key Laboratory of Lignocellulosic Chemistry , Beijing Forestry University , Beijing 100083 , China
| | - Dayong Ding
- Beijing Key Laboratory of Lignocellulosic Chemistry , Beijing Forestry University , Beijing 100083 , China
| | - Tingting You
- Beijing Key Laboratory of Lignocellulosic Chemistry , Beijing Forestry University , Beijing 100083 , China
| | - Xun Zhang
- Beijing Key Laboratory of Lignocellulosic Chemistry , Beijing Forestry University , Beijing 100083 , China
| | - Keiji Takabe
- Laboratory of Tree Cell Biology, Graduate School of Agriculture , Kyoto University , Kyoto , 606-8502 , Japan
| | - Feng Xu
- Beijing Key Laboratory of Lignocellulosic Chemistry , Beijing Forestry University , Beijing 100083 , China
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35
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Yao L, Yoo CG, Meng X, Li M, Pu Y, Ragauskas AJ, Yang H. A structured understanding of cellobiohydrolase I binding to poplar lignin fractions after dilute acid pretreatment. BIOTECHNOLOGY FOR BIOFUELS 2018; 11:96. [PMID: 29632555 PMCID: PMC5883885 DOI: 10.1186/s13068-018-1087-y] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2017] [Accepted: 01/11/2018] [Indexed: 05/24/2023]
Abstract
BACKGROUND Cellulase adsorption to lignin is considered a cost barrier for bioethanol production; however, its detailed association mechanism is still not fully understood. In this study, two natural poplar variants with high and low sugar release performance were selected as the low and high recalcitrant raw materials (named L and H, respectively). Three different lignin fractions were extracted using ethanol, followed by p-dioxane and then cellulase treatment from the dilute acid pretreated poplar solids (fraction 1, 2, and 3, respectively). RESULTS Each lignin fraction had different physicochemical properties. Ethanol-extracted lignin had the lowest weight average molecular weight, while the molecular weights for the other two lignin fractions were similar. 31P NMR analysis revealed that lignin fraction with higher molecular weight contained more aliphatic hydroxyl groups and less phenolic hydroxyl groups. Semi-quantitative analysis by 2D HSQC NMR indicated that the lignin fractions isolated from the natural variants had different contents of syringyl (S), guaiacyl (G) and interunit linkages. Lignin extracted by ethanol contained the largest amount of S units, the smallest amounts of G and p-hydroxybenzoate (PB) subunits, while the contents of these lignin subunits in the other two lignin fractions were similar. The lignin fraction obtained after cellulase treatment was primarily comprised of β-O-4 linkages with small amounts of β-5 and β-β linkages. The binding strength of these three lignin fractions obtained by Langmuir equations were in the order of L1 > L3 > L2 for the low recalcitrance poplar and H1 > H2 > H3 for the high recalcitrance poplar. CONCLUSIONS Overall, adsorption ability of lignin was correlated with the sugar release of poplar. Structural features of lignin were associated with its binding to CBH. For natural poplar variants, lignin fractions with lower molecular weight and polydispersity index (PDI) exhibited more CBH adsorption ability. Lignins with more phenolic hydroxyl groups had higher CBH binding strength. It was also found that lignin fractions with more condensed aromatics adsorbed more CBH likely attributed to stronger hydrophobic interactions.
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Affiliation(s)
- Lan Yao
- School of Pulp & Paper Engineering, Hubei University of Technology, Wuhan, 430068 China
- Hubei Provincial Key Laboratory of Green Materials for Light Industry, Hubei University of Technology, Wuhan, 430068 China
- Department of Chemical and Biomolecular Engineering, The University of Tennessee, Knoxville, TN 37996-2200 USA
| | - Chang Geun Yoo
- Joint Institute for Biological Sciences, Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 USA
| | - Xianzhi Meng
- Department of Chemical and Biomolecular Engineering, The University of Tennessee, Knoxville, TN 37996-2200 USA
| | - Mi Li
- Joint Institute for Biological Sciences, Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 USA
| | - Yunqiao Pu
- Joint Institute for Biological Sciences, Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 USA
| | - Arthur J. Ragauskas
- Joint Institute for Biological Sciences, Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 USA
- Department of Chemical and Biomolecular Engineering, The University of Tennessee, Knoxville, TN 37996-2200 USA
- Department of Forestry, Wildlife and Fisheries, Center for Renewable Carbon, Institute of Agriculture, The University of Tennessee, Knoxville, TN 37996-2200 USA
| | - Haitao Yang
- School of Pulp & Paper Engineering, Hubei University of Technology, Wuhan, 430068 China
- Hubei Provincial Key Laboratory of Green Materials for Light Industry, Hubei University of Technology, Wuhan, 430068 China
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36
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Schutyser W, Renders T, Van den Bosch S, Koelewijn SF, Beckham GT, Sels BF. Chemicals from lignin: an interplay of lignocellulose fractionation, depolymerisation, and upgrading. Chem Soc Rev 2018; 47:852-908. [PMID: 29318245 DOI: 10.1039/c7cs00566k] [Citation(s) in RCA: 846] [Impact Index Per Article: 141.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
In pursuit of more sustainable and competitive biorefineries, the effective valorisation of lignin is key. An alluring opportunity is the exploitation of lignin as a resource for chemicals. Three technological biorefinery aspects will determine the realisation of a successful lignin-to-chemicals valorisation chain, namely (i) lignocellulose fractionation, (ii) lignin depolymerisation, and (iii) upgrading towards targeted chemicals. This review provides a summary and perspective of the extensive research that has been devoted to each of these three interconnected biorefinery aspects, ranging from industrially well-established techniques to the latest cutting edge innovations. To navigate the reader through the overwhelming collection of literature on each topic, distinct strategies/topics were delineated and summarised in comprehensive overview figures. Upon closer inspection, conceptual principles arise that rationalise the success of certain methodologies, and more importantly, can guide future research to further expand the portfolio of promising technologies. When targeting chemicals, a key objective during the fractionation and depolymerisation stage is to minimise lignin condensation (i.e. formation of resistive carbon-carbon linkages). During fractionation, this can be achieved by either (i) preserving the (native) lignin structure or (ii) by tolerating depolymerisation of the lignin polymer but preventing condensation through chemical quenching or physical removal of reactive intermediates. The latter strategy is also commonly applied in the lignin depolymerisation stage, while an alternative approach is to augment the relative rate of depolymerisation vs. condensation by enhancing the reactivity of the lignin structure towards depolymerisation. Finally, because depolymerised lignins often consist of a complex mixture of various compounds, upgrading of the raw product mixture through convergent transformations embodies a promising approach to decrease the complexity. This particular upgrading approach is termed funneling, and includes both chemocatalytic and biological strategies.
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Affiliation(s)
- W Schutyser
- Center for Surface Chemistry and Catalysis, KU Leuven, Celestijnenlaan 200F, 3001 Heverlee, Belgium.
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Physico-Chemical Conversion of Lignocellulose: Inhibitor Effects and Detoxification Strategies: A Mini Review. Molecules 2018; 23:molecules23020309. [PMID: 29389875 PMCID: PMC6017906 DOI: 10.3390/molecules23020309] [Citation(s) in RCA: 164] [Impact Index Per Article: 27.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2017] [Revised: 01/18/2018] [Accepted: 01/30/2018] [Indexed: 11/20/2022] Open
Abstract
A pretreatment of lignocellulosic biomass to produce biofuels, polymers, and other chemicals plays a vital role in the biochemical conversion process toward disrupting the closely associated structures of the cellulose-hemicellulose-lignin molecules. Various pretreatment steps alter the chemical/physical structure of lignocellulosic materials by solubilizing hemicellulose and/or lignin, decreasing the particle sizes of substrate and the crystalline portions of cellulose, and increasing the surface area of biomass. These modifications enhance the hydrolysis of cellulose by increasing accessibilities of acids or enzymes onto the surface of cellulose. However, lignocellulose-derived byproducts, which can inhibit and/or deactivate enzyme and microbial biocatalysts, are formed, including furan derivatives, lignin-derived phenolics, and carboxylic acids. These generation of compounds during pretreatment with inhibitory effects can lead to negative effects on subsequent steps in sugar flat-form processes. A number of physico-chemical pretreatment methods such as steam explosion, ammonia fiber explosion (AFEX), and liquid hot water (LHW) have been suggested and developed for minimizing formation of inhibitory compounds and alleviating their effects on ethanol production processes. This work reviews the physico-chemical pretreatment methods used for various biomass sources, formation of lignocellulose-derived inhibitors, and their contributions to enzymatic hydrolysis and microbial activities. Furthermore, we provide an overview of the current strategies to alleviate inhibitory compounds present in the hydrolysates or slurries.
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38
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Qing Q, Gao X, Wang P, Guo Q, Xu Z, Wang L. Dilute acid catalyzed fractionation and sugar production from bamboo shoot shell in γ-valerolactone/water medium. RSC Adv 2018; 8:17527-17534. [PMID: 35539230 PMCID: PMC9080427 DOI: 10.1039/c8ra02891e] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2018] [Accepted: 04/25/2018] [Indexed: 12/31/2022] Open
Abstract
Overcoming the recalcitrance barrier of cellulosic biomass for efficient production of fermentable sugars at low cost is the current limitation for the industrialization of lignocellulosic biorefineries. In the present work, a two-step non-enzymatic strategy was developed for the fractionation of the main components in bamboo shoot shell (BSS) and conversion of polysaccharides into fermentable sugars by dilute acid in a γ-valerolactone (GVL)/H2O solvent system. About 86.0% of lignin and 87.4% of hemicelluloses were removed in the first step by 0.6% H2SO4 under 140 °C for 1 h with the addition of 60% GVL. The residue solids enriched with cellulose were then subjected to acid hydrolysis employing 0.05% H2SO4 as the catalyst in 80% GVL at 180 °C for 20 min. The maximum total soluble sugar yield achieved in the acid hydrolysate was 70.7%. This research could provide valuable insights into the valorization of lignocellulosic biomass and become a promising alternative to the biomass-derived carbohydrate production scheme. A non-enzymatic method is reported for the production of fermentable sugars from lignocellulose with a high total sugar recovery.![]()
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Affiliation(s)
- Qing Qing
- Department of Biochemical Engineering
- College of Pharmaceutical Engineering and Life Science
- Changzhou University
- Changzhou 213164
- China
| | - Xiaohang Gao
- Department of Biochemical Engineering
- College of Pharmaceutical Engineering and Life Science
- Changzhou University
- Changzhou 213164
- China
| | - Pengbo Wang
- Department of Biochemical Engineering
- College of Pharmaceutical Engineering and Life Science
- Changzhou University
- Changzhou 213164
- China
| | - Qi Guo
- Department of Biochemical Engineering
- College of Pharmaceutical Engineering and Life Science
- Changzhou University
- Changzhou 213164
- China
| | - Zhong Xu
- Department of Biochemical Engineering
- College of Pharmaceutical Engineering and Life Science
- Changzhou University
- Changzhou 213164
- China
| | - Liqun Wang
- Department of Biochemical Engineering
- College of Pharmaceutical Engineering and Life Science
- Changzhou University
- Changzhou 213164
- China
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Yao L, Yang H, Yoo CG, Meng X, Li M, Pu Y, Ragauskas AJ, Sykes RW. Adsorption of cellobiohydrolases I onto lignin fractions from dilute acid pretreated Broussonetia papyrifera. BIORESOURCE TECHNOLOGY 2017; 244:957-962. [PMID: 28847086 DOI: 10.1016/j.biortech.2017.08.024] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2017] [Revised: 08/04/2017] [Accepted: 08/05/2017] [Indexed: 06/07/2023]
Abstract
Broussonetia papyrifera, known as paper mulberry, is a potential feed stock for bioethanol production because of its cellulose-rich composition. Lignin in dilute acid pretreated Broussonetia papyrifera was fractionated to three different fractions, and their physiochemical properties were determined by FT-IR, GPC and NMR analyses. Different structural characteristics were observed from each lignin fraction. Cellobiohydrolases I (CBH) adsorption to each lignin was understood by the lignin properties. The results showed that aliphatic hydroxyl groups in lignin showed positive correlations with the maximum binding ability of CBH onto lignin samples. Also, the contents of phenolic compounds such as p-hydroxyphenyl benzoate (PB), syringyl (S) and guaiacyl (G) units in the lignin influenced their CBH binding.
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Affiliation(s)
- Lan Yao
- School of Pulp & Paper Engineering, Hubei University of Technology, Wuhan 430068, China; State Key Laboratory of Pulp and Paper Engineering, South China University of Technology, Guangzhou 510640, China; Department of Chemical and Biomolecular Engineering, The University of Tennessee, Knoxville, TN 37996-2200, USA
| | - Haitao Yang
- School of Pulp & Paper Engineering, Hubei University of Technology, Wuhan 430068, China
| | - Chang Geun Yoo
- Joint Institute for Biological Sciences, Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Xianzhi Meng
- Department of Chemical and Biomolecular Engineering, The University of Tennessee, Knoxville, TN 37996-2200, USA
| | - Mi Li
- Joint Institute for Biological Sciences, Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Yunqiao Pu
- Joint Institute for Biological Sciences, Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Arthur J Ragauskas
- Joint Institute for Biological Sciences, Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA; Department of Chemical and Biomolecular Engineering, The University of Tennessee, Knoxville, TN 37996-2200, USA; Department of Forestry, Wildlife and Fisheries, Center of Renewable Carbon, The University of Tennessee, Institute of Agriculture, Knoxville, TN 37996-2200, USA.
| | - Robert W Sykes
- National Bioenergy Center, National Renewable Energy Laboratory, Golden, CO 80401, USA
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Li J, Hu H, Li H, Huang L, Chen L, Ni Y. Kinetics and mechanism of hemicelluloses removal from cellulosic fibers during the cold caustic extraction process. BIORESOURCE TECHNOLOGY 2017; 234:61-66. [PMID: 28319774 DOI: 10.1016/j.biortech.2017.03.026] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2017] [Revised: 03/03/2017] [Accepted: 03/04/2017] [Indexed: 06/06/2023]
Abstract
The effective separation of hemicelluloses and cellulose is desirable for the production of high-purity cellulose, which is a sustainable raw material for many value-added applications. For this purpose, the kinetics and mechanism of hemicelluloses removal from the cold caustic extraction (CCE) were investigated in the present study. The hemicelluloses removal process consists of: 1) the bulk phase, characteristic of significant hemicelluloses removal; 2) the transition phase, hemicelluloses transferring from the inner to the outer region of the fiber wall, with negligible overall hemicelluloses removal; 3) the residual phase, presenting a weak but continuing hemicelluloses removal. Furthermore, the enzymatic peeling method was adopted to study the fundamentals of hemicelluloses removal. The results showed that the molecular weight of hemicelluloses is the main parameter governing their diffusion/dissolution processes, and that the low molecular weight hemicelluloses are preferentially removed.
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Affiliation(s)
- Jianguo Li
- College of Material Engineering, Fujian Agriculture and Forestry University, Fuzhou 350002, China; Limerick Pulp and Paper Centre, Department of Chemical Engineering, University of New Brunswick, Fredericton, New Brunswick E3B 5A3, Canada; Key Laboratory of Pulp and Paper Science & Technology of Ministry of Education/Shandong Province, Qilu University of Technology, Jinan 250353, China
| | - Huichao Hu
- College of Material Engineering, Fujian Agriculture and Forestry University, Fuzhou 350002, China; Limerick Pulp and Paper Centre, Department of Chemical Engineering, University of New Brunswick, Fredericton, New Brunswick E3B 5A3, Canada
| | - Hailong Li
- Limerick Pulp and Paper Centre, Department of Chemical Engineering, University of New Brunswick, Fredericton, New Brunswick E3B 5A3, Canada; Tianjin Key Laboratory of Pulp and Paper, Tianjin University of Science and Technology, Tianjin 300457, China
| | - Liulian Huang
- College of Material Engineering, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Lihui Chen
- College of Material Engineering, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Yonghao Ni
- College of Material Engineering, Fujian Agriculture and Forestry University, Fuzhou 350002, China; Limerick Pulp and Paper Centre, Department of Chemical Engineering, University of New Brunswick, Fredericton, New Brunswick E3B 5A3, Canada.
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Release of Polyphenols Is the Major Factor Influencing the Bioconversion of Rice Straw to Lactic Acid. Appl Biochem Biotechnol 2017; 183:685-698. [DOI: 10.1007/s12010-017-2457-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Accepted: 03/12/2017] [Indexed: 10/19/2022]
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Li M, Pu Y, Yoo CG, Gjersing E, Decker SR, Doeppke C, Shollenberger T, Tschaplinski TJ, Engle NL, Sykes RW, Davis MF, Baxter HL, Mazarei M, Fu C, Dixon RA, Wang ZY, Neal Stewart C, Ragauskas AJ. Study of traits and recalcitrance reduction of field-grown COMT down-regulated switchgrass. BIOTECHNOLOGY FOR BIOFUELS 2017; 10:12. [PMID: 28053668 PMCID: PMC5209956 DOI: 10.1186/s13068-016-0695-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2016] [Accepted: 12/23/2016] [Indexed: 05/22/2023]
Abstract
BACKGROUND The native recalcitrance of plants hinders the biomass conversion process using current biorefinery techniques. Down-regulation of the caffeic acid O-methyltransferase (COMT) gene in the lignin biosynthesis pathway of switchgrass reduced the thermochemical and biochemical conversion recalcitrance of biomass. Due to potential environmental influences on lignin biosynthesis and deposition, studying the consequences of physicochemical changes in field-grown plants without pretreatment is essential to evaluate the performance of lignin-altered plants. We determined the chemical composition, cellulose crystallinity and the degree of its polymerization, molecular weight of hemicellulose, and cellulose accessibility of cell walls in order to better understand the fundamental features of why biomass is recalcitrant to conversion without pretreatment. The most important is to investigate whether traits and features are stable in the dynamics of field environmental effects over multiple years. RESULTS Field-grown COMT down-regulated plants maintained both reduced cell wall recalcitrance and lignin content compared with the non-transgenic controls for at least 3 seasons. The transgenic switchgrass yielded 35-84% higher total sugar release (enzymatic digestibility or saccharification) from a 72-h enzymatic hydrolysis without pretreatment and also had a 25-32% increase in enzymatic sugar release after hydrothermal pretreatment. The COMT-silenced switchgrass lines had consistently lower lignin content, e.g., 12 and 14% reduction for year 2 and year 3 growing season, respectively, than the control plants. By contrast, the transgenic lines had 7-8% more xylan and galactan contents than the wild-type controls. Gel permeation chromatographic results revealed that the weight-average molecular weights of hemicellulose were 7-11% lower in the transgenic than in the control lines. In addition, we found that silencing of COMT in switchgrass led to 20-22% increased cellulose accessibility as measured by the Simons' stain protocol. No significant changes were observed on the arabinan and glucan contents, cellulose crystallinity, and cellulose degree of polymerization between the transgenic and control plants. With the 2-year comparative analysis, both the control and transgenic lines had significant increases in lignin and glucan contents and hemicellulose molecular weight across the growing seasons. CONCLUSIONS The down-regulation of COMT in switchgrass resulting in a reduced lignin content and biomass recalcitrance is stable in a field-grown trial for at least three seasons. Among the determined affecting factors, the reduced biomass recalcitrance of the COMT-silenced switchgrass, grown in the field conditions for two and three seasons, was likely related to the decreased lignin content and increased biomass accessibility, whereas the cellulose crystallinity and degree of its polymerization and hemicellulose molecular weights did not contribute to the reduction of recalcitrance significantly. This finding suggests that lignin down-regulation in lignocellulosic feedstock confers improved saccharification that translates from greenhouse to field trial and that lignin content and biomass accessibility are two significant factors for developing a reduced recalcitrance feedstock by genetic modification.
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Affiliation(s)
- Mi Li
- BioEnergy Science Center (BESC), Oak Ridge National Laboratory (ORNL), Oak Ridge, TN USA
- BioSciences Division, ORNL, Oak Ridge, TN USA
- UT-ORNL Joint Institute for Biological Sciences, Oak Ridge, TN USA
| | - Yunqiao Pu
- BioEnergy Science Center (BESC), Oak Ridge National Laboratory (ORNL), Oak Ridge, TN USA
- BioSciences Division, ORNL, Oak Ridge, TN USA
- UT-ORNL Joint Institute for Biological Sciences, Oak Ridge, TN USA
| | - Chang Geun Yoo
- BioEnergy Science Center (BESC), Oak Ridge National Laboratory (ORNL), Oak Ridge, TN USA
- BioSciences Division, ORNL, Oak Ridge, TN USA
- UT-ORNL Joint Institute for Biological Sciences, Oak Ridge, TN USA
| | - Erica Gjersing
- Biosciences Center, National Renewable Energy Laboratory (NREL), Golden, CO USA
| | - Stephen R. Decker
- Biosciences Center, National Renewable Energy Laboratory (NREL), Golden, CO USA
| | - Crissa Doeppke
- Biosciences Center, National Renewable Energy Laboratory (NREL), Golden, CO USA
| | - Todd Shollenberger
- Biosciences Center, National Renewable Energy Laboratory (NREL), Golden, CO USA
| | - Timothy J. Tschaplinski
- BioEnergy Science Center (BESC), Oak Ridge National Laboratory (ORNL), Oak Ridge, TN USA
- BioSciences Division, ORNL, Oak Ridge, TN USA
- UT-ORNL Joint Institute for Biological Sciences, Oak Ridge, TN USA
| | - Nancy L. Engle
- BioEnergy Science Center (BESC), Oak Ridge National Laboratory (ORNL), Oak Ridge, TN USA
- BioSciences Division, ORNL, Oak Ridge, TN USA
- UT-ORNL Joint Institute for Biological Sciences, Oak Ridge, TN USA
| | | | | | - Holly L. Baxter
- BioEnergy Science Center (BESC), Oak Ridge National Laboratory (ORNL), Oak Ridge, TN USA
- Department of Plant Sciences, University of Tennessee, Knoxville, TN USA
| | - Mitra Mazarei
- BioEnergy Science Center (BESC), Oak Ridge National Laboratory (ORNL), Oak Ridge, TN USA
- Department of Plant Sciences, University of Tennessee, Knoxville, TN USA
| | - Chunxiang Fu
- Forage Improvement Division, The Samuel Roberts Noble Foundation, Ardmore, OK USA
| | - Richard A. Dixon
- BioEnergy Science Center (BESC), Oak Ridge National Laboratory (ORNL), Oak Ridge, TN USA
- BioDiscovery Institute and Department of Biological Sciences, University of North Texas, Denton, TX USA
| | - Zeng-Yu Wang
- BioEnergy Science Center (BESC), Oak Ridge National Laboratory (ORNL), Oak Ridge, TN USA
- Forage Improvement Division, The Samuel Roberts Noble Foundation, Ardmore, OK USA
| | - C. Neal Stewart
- BioEnergy Science Center (BESC), Oak Ridge National Laboratory (ORNL), Oak Ridge, TN USA
- Department of Plant Sciences, University of Tennessee, Knoxville, TN USA
| | - Arthur J. Ragauskas
- BioEnergy Science Center (BESC), Oak Ridge National Laboratory (ORNL), Oak Ridge, TN USA
- BioSciences Division, ORNL, Oak Ridge, TN USA
- UT-ORNL Joint Institute for Biological Sciences, Oak Ridge, TN USA
- Department of Chemical and Biomolecular Engineering & Department of Forestry, Wildlife and Fisheries, University of Tennessee, Knoxville, TN USA
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Li M, Cao S, Meng X, Studer M, Wyman CE, Ragauskas AJ, Pu Y. The effect of liquid hot water pretreatment on the chemical-structural alteration and the reduced recalcitrance in poplar. BIOTECHNOLOGY FOR BIOFUELS 2017; 10:237. [PMID: 29213308 PMCID: PMC5707831 DOI: 10.1186/s13068-017-0926-6] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2017] [Accepted: 10/06/2017] [Indexed: 05/12/2023]
Abstract
BACKGROUND Hydrothermal pretreatment using liquid hot water (LHW) is capable of substantially reducing the cell wall recalcitrance of lignocellulosic biomass. It enhances the saccharification of polysaccharides, particularly cellulose, into glucose with relatively low capital required. Due to the close association with biomass recalcitrance, the structural change of the components of lignocellulosic materials during the pretreatment is crucial to understand pretreatment chemistry and advance the bio-economy. Although the LHW pretreatment has been extensively applied and studied, the molecular structural alteration during pretreatment and its significance to reduced recalcitrance have not been well understood. RESULTS We investigated the effects of LHW pretreatment with different severity factors (log R0) on the structural changes of fast-grown poplar (Populus trichocarpa). With the severity factor ranging from 3.6 to 4.2, LHW pretreatment resulted in a substantial xylan solubilization by 50-77% (w/w, dry matter). The molecular weights of the remained hemicellulose in pretreated solids also have been significantly reduced by 63-75% corresponding to LHW severity factor from 3.6 to 4.2. In addition, LHW had a considerable impact on the cellulose structure. The cellulose crystallinity increased 6-9%, whereas its degree of polymerization decreased 35-65% after pretreatment. We found that the pretreatment severity had an empirical linear correlation with the xylan solubilization (R2 = 0.98, r = + 0.99), hemicellulose molecular weight reduction (R2 = 0.97, r = - 0.96 and R2 = 0.93, r = - 0.98 for number-average and weight-average degree of polymerization, respectively), and cellulose crystallinity index increase (R2 = 0.98, r = + 0.99). The LHW pretreatment also resulted in small changes in lignin structure such as decrease of β-O-4' ether linkages and removal of cinnamyl alcohol end group and acetyl group, while the S/G ratio of lignin in LHW pretreated poplar residue remained no significant change compared with the untreated poplar. CONCLUSIONS This study revealed that the solubilization of xylan, the reduction of hemicellulose molecular weights and cellulose degree of polymerization, and the cleavage of alkyl-aryl ether bonds in lignin resulted from LHW pretreatment are critical factors associated with reduced cell wall recalcitrance. The chemical-structural changes of the three major components, cellulose, lignin, and hemicellulose, during LHW pretreatment provide useful and fundamental information of factors governing feedstock recalcitrance during hydrothermal pretreatment.
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Affiliation(s)
- Mi Li
- BioEnergy Science Center (BESC), Oak Ridge, USA
- Biosciences Division, ORNL, Oak Ridge, TN USA
| | - Shilin Cao
- School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, GA USA
- Present Address: College of Material Engineering, Fujian Agriculture and Forestry University, Fuzhou, People’s Republic of China
| | - Xianzhi Meng
- Department of Chemical and Biomolecular Engineering, University of Tennessee, Knoxville, TN USA
| | - Michael Studer
- BioEnergy Science Center (BESC), Oak Ridge, USA
- College of Engineering - Center for Environmental Research and Technology (CE-CERT), Bourns College of Engineering, University of California, Riverside, CA USA
- Present Address: Laboratory for Bioenergy and Biochemicals, School of Agricultural, Forest and Food Sciences, Bern University of Applied Sciences, Bern, Switzerland
| | - Charles E. Wyman
- BioEnergy Science Center (BESC), Oak Ridge, USA
- College of Engineering - Center for Environmental Research and Technology (CE-CERT), Bourns College of Engineering, University of California, Riverside, CA USA
| | - Arthur J. Ragauskas
- BioEnergy Science Center (BESC), Oak Ridge, USA
- Biosciences Division, ORNL, Oak Ridge, TN USA
- Department of Chemical and Biomolecular Engineering, University of Tennessee, Knoxville, TN USA
- Department of Forestry, Wildlife, and Fisheries, Center for Renewable Carbon, University of Tennessee Institute of Agriculture, Knoxville, TN USA
| | - Yunqiao Pu
- BioEnergy Science Center (BESC), Oak Ridge, USA
- Biosciences Division, ORNL, Oak Ridge, TN USA
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Ethanol and hydrogen production from sunflower straw: The effect of pretreatment on the whole slurry fermentation. Biochem Eng J 2016. [DOI: 10.1016/j.bej.2016.06.014] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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46
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Ji Z, Zhang X, Ling Z, Sun RC, Xu F. Tissue specific response of Miscanthus×giganteus to dilute acid pretreatment for enhancing cellulose digestibility. Carbohydr Polym 2016; 154:247-56. [PMID: 27577916 DOI: 10.1016/j.carbpol.2016.06.086] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2016] [Revised: 06/20/2016] [Accepted: 06/20/2016] [Indexed: 10/21/2022]
Abstract
The recalcitrance in grasses varies according to cell type and tissue. In this study, dilute acid pretreatment was performed on Miscanthus×giganteus internodes that include rind and pith regions which showing heterogeneous structural and chemical changes. Pretreatment on pith effectively hydrolyzed 73.33% hemicelluloses and separated cohesive cell walls from the compound middle lamella due to lignin migration. Lignin droplets with an average diameter of 49.5±29.3nm were concurrently coalesced on wall surface, that in turn exposed more microfibrils deep in walls to be enzymatically hydrolyzed reaching 82.55%. By contrast, the rind with a relatively intergrated cell structure was covered by larger lignin droplets (101.2±44.1nm) and filled with inaccessible microfibrils limiting enzymatic sacchrification (31.50%). Taken together, the cellulose digestibility of biomass was not majorly influenced by cellulose crystallinity, while it was strongly correlated with the positive effects of hemicelluloses degradation, lignin redistribution, cellulose exposure and loosening cell wall structure.
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Affiliation(s)
- Zhe Ji
- Beijing Key Laboratory of Lignocellulosic Chemistry, Beijing Forestry University, Beijing 100083, China; College of Chemistry and Molecular Engineering, Qingdao University of Science and Technology, Qingdao 266042, China
| | - Xun Zhang
- Beijing Key Laboratory of Lignocellulosic Chemistry, Beijing Forestry University, Beijing 100083, China
| | - Zhe Ling
- Beijing Key Laboratory of Lignocellulosic Chemistry, Beijing Forestry University, Beijing 100083, China
| | - Run-Cang Sun
- Beijing Key Laboratory of Lignocellulosic Chemistry, Beijing Forestry University, Beijing 100083, China
| | - Feng Xu
- Beijing Key Laboratory of Lignocellulosic Chemistry, Beijing Forestry University, Beijing 100083, China; Shandong Key Laboratory of Pulping and Papermaking Engineering, Qilu University of Technology, Jinan 250353, China.
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Abstract
Eruca sativa plant offers a great potential to utilized for multiple biofuel production through a biorefining prospective to maximize the biodiesel, biogas, and ethanol production yields.
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Affiliation(s)
- Hamed Bateni
- Department of Chemical Engineering
- Isfahan University of Technology
- Isfahan 84156-83111
- Iran
- Chemical and Biomolecular Engineering Department
| | - Keikhosro Karimi
- Department of Chemical Engineering
- Isfahan University of Technology
- Isfahan 84156-83111
- Iran
- Industrial Biotechnology Group
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Vargas F, Domínguez E, Vila C, Rodríguez A, Garrote G. Agricultural residue valorization using a hydrothermal process for second generation bioethanol and oligosaccharides production. BIORESOURCE TECHNOLOGY 2015; 191:263-270. [PMID: 26000836 DOI: 10.1016/j.biortech.2015.05.035] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2015] [Revised: 05/11/2015] [Accepted: 05/12/2015] [Indexed: 06/04/2023]
Abstract
In the present work, the hydrothermal valorization of an abundant agricultural residue has been studied in order to look for high added value applications by means of hydrothermal pretreatment followed by fed-batch simultaneous saccharification and fermentation, to obtain oligomers and sugars from autohydrolysis liquors and bioethanol from the solid phase. Non-isothermal autohydrolysis was applied to barley straw, leading to a solid phase with about a 90% of glucan and lignin and a liquid phase with up to 168 g kg(-1) raw material valuable hemicellulose-derived compounds. The solid phase showed a high enzymatic susceptibility (up to 95%). It was employed in the optimization study of the fed-batch simultaneous saccharification and fermentation, carried out at high solids loading, led up to 52 g ethanol/L (6.5% v/v).
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Affiliation(s)
- Fátima Vargas
- Department of Chemical Engineering, Faculty of Science, University of Cordoba, Campus of Rabanales, Marie-Curie Building (C-3), N-IV Road, km. 396, 14071 Cordoba, Spain
| | - Elena Domínguez
- Department of Chemical Engineering, Faculty of Science, University of Vigo (Campus Ourense), As Lagoas, 32004 Ourense, Spain; CITI (Centro de Investigación, Transferencia e Innovación), University of Vigo, Tecnopole, San Cibrao das Viñas, Ourense, Spain
| | - Carlos Vila
- Department of Chemical Engineering, Faculty of Science, University of Vigo (Campus Ourense), As Lagoas, 32004 Ourense, Spain; CITI (Centro de Investigación, Transferencia e Innovación), University of Vigo, Tecnopole, San Cibrao das Viñas, Ourense, Spain
| | - Alejandro Rodríguez
- Department of Chemical Engineering, Faculty of Science, University of Cordoba, Campus of Rabanales, Marie-Curie Building (C-3), N-IV Road, km. 396, 14071 Cordoba, Spain
| | - Gil Garrote
- Department of Chemical Engineering, Faculty of Science, University of Vigo (Campus Ourense), As Lagoas, 32004 Ourense, Spain; CITI (Centro de Investigación, Transferencia e Innovación), University of Vigo, Tecnopole, San Cibrao das Viñas, Ourense, Spain.
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Ma J, Ji Z, Chen JC, Zhou X, Kim YS, Xu F. The mechanism of xylans removal during hydrothermal pretreatment of poplar fibers investigated by immunogold labeling. PLANTA 2015; 242:327-337. [PMID: 25926363 DOI: 10.1007/s00425-015-2313-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2015] [Accepted: 04/21/2015] [Indexed: 06/04/2023]
Abstract
Hydrothermal pretreatment initially removed the lignin-free xylan from the middle layer of secondary wall, followed by the lignin-bound xylan, but the cellulose-bound xylan was seldom removed by this pretreatment. An in-depth understanding of the mechanism of xylan removal during hydrothermal pretreatment (HTP) of wood is critical for cost-effective conversion of lignocellulosic biomass to biofuels. Several studies demonstrated the kinetics and mechanism of xylan removal during HTP on molecular scale, but the dissolution mechanism of xylan during HTP remains unclear at ultra-structural level. Our study investigated changes in the micro-distribution of xylan in poplar fiber cell walls during HTP by transmission electron microscopy (TEM) in combination with immunogold labeling. The study revealed that HTP caused greater decline in the density of xylan labeling in the S2 layer of fiber wall than in the S1 layer. There was a greater loss in the density of xylan labeling during HTP in the delignified and enzymatically treated fibers compared to untreated fibers. We propose that in the initial stages of HTP lignin-free xylan in the S2 layer was more readily hydrolyzed than in the S1 layer by hydronium ions. With increasing pretreatment time, the xylan covalently bound to lignin was also removed from the S2 layer due to the dissolution of lignin. The xylan tightly bound to cellulose was seldom removed during HTP, but was hydrolyzed in subsequent enzymatic treatment. This TEM-immunolabeling investigation reveals the manner in which different xylan fractions are removed from fiber cell wall during HTP, and we expect the information to be helpful in developing processes tailored for more effective conversion of cellulosic biomass into fermentable sugars.
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Affiliation(s)
- Jing Ma
- Beijing Key Laboratory of Lignocellulosic Chemistry, Beijing Forestry University, Beijing, 100083, China
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Rana D, Laskar DD, Srinivas K, Ahring BK. Wet explosion pretreatment of loblolly pine leads to an increase in methoxylation of the lignin. BIORESOUR BIOPROCESS 2015. [DOI: 10.1186/s40643-015-0054-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Abstract
Background
In biorefineries, various pretreatments traditionally employ hazardous chemicals (ammonia, sulfuric acid, sulfite, etc.) for opening the softwood structure and to facilitate easy accessibility of the cellulose for further downstream processing. The resultant lignin (known as technical lignin) after extraction of the carbohydrate fraction as sugars has been either burned as fuel or used in biochemical or biofuel production. It has been observed that the technical lignin after such biomass pretreatments is often more condensed and, hence, cannot be easily used to produce fine chemicals of high value. In this study, we examine lignin after wet explosion pretreatment where the biomass in subjected to oxygen to understand how these interactions will affect lignin utilization for biochemical production.
Results
In this study, the structural transformations within the softwood lignin as a response to wet explosion (WEx) pretreatment of loblolly pine at different experimental conditions (165–175 °C, 18–30 min) were examined using GC/MS and NMR spectroscopy. The results showed that the H-type structures within the lignin molecule decreased while S-type structures increased after pretreatment. Since S-type lignin sub-units have a higher degree of methoxylation compared to H units, the potential of S-type lignin to undergo re-condensation at lower temperatures (after pretreatment), by forming bonds with other lignin sub-units, is lower due to stearic hindrance, resulting in the generation of lignin with a lower tendency to form new complex lignin bindings (high-quality biorefinery lignin).
Conclusions
The less condensed biorefinery lignin generated after WEx pretreatment was found to provide a platform for production of lignin polymer with more labile β-O-4 linkages. This type of lignin could potentially be superior for the production of high-value bio-products compared to re-condensed lignin after acidic and other types of chemical pretreatments.
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