The mechanism for thermal decomposition of cellulose and its main products

Investigating the Effects of the Physicochemical Properties of Cellulose-Derived Biocarbon on Direct Carbon Solid Oxide Fuel Cell Performance

This paper presents a study of the characteristic effects of the physicochemical properties of microcrystalline cellulose and a series of biocarbon samples produced from this raw material through thermal conversion at temperatures ranging from 200 °C to 850 °C. Structural studies revealed that the biocarbon samples produced from cellulose had a relatively low degree of graphitization of the carbon and an isometric shape of the carbon particles. Based on thermal investigations using the differential thermal analysis/differential scanning calorimeter method, obtaining fully formed biocarbon samples from cellulose feedstock was possible at about 400 °C. The highest direct carbon solid oxide fuel cell (DC-SOFC) performance was found for biochar samples obtained via thermal treatment at 400-600 °C. The pyrolytic gases from cellulose decomposition had a considerable impact on the achieved current density and power density of the DC-SOFCs supplied by pure cellulose samples or biochars derived from cellulose feedstock at a lower temperature range of 200-400 °C. For the DC-SOFCs supplied by biochars synthesised at higher temperatures of 600-850 °C, the "shuttle delivery mechanism" had a substantial effect. The impact of the carbon oxide concentration in the anode or carbon bed was important for the performance of the DC-SOFCs. Carbon oxide oxidised at the anode to form carbon dioxide, which interacted with the carbon bed to form more carbon oxide. The application of biochar obtained from cellulose alone without an additional catalyst led to moderate electrochemical power output from the DC-SOFCs. The results show that catalysts for the reverse Boudouard reactions occurring in a biocarbon bed are critical to ensuring high performance and stable operation under electrical load, which is crucial for DC-SOFC development.

Biopolymer electrolyte from banana powder-konjac glucomannan for zinc-ion batteries

Herein, the novel eco-friendly biopolymer electrolytes consisting of banana powder and konjac glucomannan host matrix doped with zinc acetate salt were successfully fabricated through simple casting technique. The biopolymer electrolyte exhibited satisfactory thermal stability and mechanical properties; tensile strength (13.82 MPa); elongation at break (60.52 %) and Young's modulus (93.2 MPa). The electrochemical studies were carried out in symmetrical cells Zn/Zn cells. Biopolymer electrolyte showed favorable ionic conductivity of 5.59 × 10-4 S/cm along with stable cycling performance. The potential stability was found to be 2.52 V. The as-prepared biopolymer electrolytes demonstrated the potential as green, simple yet effective biopolymer electrolytes for zinc-ion batteries.

Understanding cellulose pyrolysis via ab initio deep learning potential field

Comprehensive and dynamic studies of cellulose pyrolysis reaction mechanisms are crucial in designing experiments and processes with enhanced safety, efficiency, and sustainability. The details of the pyrolysis mechanism are not readily available from experiments but can be better described via molecular dynamics (MD) simulations. However, the large size of cellulose molecules challenges accurate ab initio MD simulations, while existing reactive force field parameters lack precision. In this work, precise ab initio deep learning potentials field (DPLF) are developed and applied in MD simulations to facilitate the study of cellulose pyrolysis mechanisms. The formation mechanism and production rate of both valuable and greenhouse products from cellulose at temperatures larger than 1073 K are comprehensively described. This study underscores the critical role of advanced simulation techniques, particularly DLPF, in achieving efficient and accurate understanding of cellulose pyrolysis mechanisms, thus promoting wider industrial applications.

Cellulose/silica composite microtubular superfoam with excellent flame retardancy, thermal insulation and ablative resistance

Thermal insulation materials with good flame-retardant properties have attracted widespread attention because of their huge application potential. Traditional petrochemical-based polymer insulation materials are flammable and have problems with environmental pollution. The microtubule structure is a perfect microstructure with excellent thermal insulation performance. In addition, the microtubule structure also has low density and high elasticity. Therefore, the microtubule structure is an important reference microstructure for the development of efficient thermal insulation materials. In this paper, a cellulose/SiO2 composite microtube thermal insulation superfoam has been successfully prepared. Cellulose microtubules were successfully prepared from poplar sawdust by chemical methods. The SiO2 aerogel precursor solution can be quickly adsorbed by the delignified cellulose microtubes. The SiO2 aerogel shells are evenly distributed only on the inner and outer walls of the delignified cellulose microtubes. The cellulose/SiO2 microtube composite (CSMC) superfoam exhibits low density, good mechanical properties, and low thermal conductivity (as low as 0.042 ± 0.0018 W m-1 K-1). The CSMC superfoam exhibits excellent self-extinguishing and flame-retardant properties. After being burned by a butane flame, the superfoam still has certain mechanical properties. The thermal conductivity of the B-CSMC superfoam (the CSMC superfoam burned by a butane flame) is about 0.050 W m-1 K-1. The B-CSMC superfoam remained almost unchanged after being continuously ablated by a butane flame for 3600 seconds.

Constructing a "micro-nano collaboration" network via disk-milling: Value-enhanced utilization of flexible temperature-resistant cellulose insulation films

Cellulose is a sustainable natural polymer material that has found widespread application in transformers and other power equipment because of its excellent electrical and mechanical performance. However, the utility of cellulose materials has been limited by the challenge of balancing heat resistance with flexibility. On the basis of the preliminary research conducted by the research team, further proposals have been put forward for a method involving disk milling to create a "micro-nanocollaboration" network for the fabrication of flexible, high-temperature-resistant, and ultrafine fiber-based cellulose insulating films. The resulting full-component cellulose films exhibited impressive properties, including high tensile strength (22 MPa), flexibility (92-263 mN), remarkable electrical breakdown strength (39 KV/mm), and volume resistivity that meets the standards for insulation materials (4.92 × 1011 Ω·m). These results demonstrate that the proposed method can produce full-component cellulose insulation films that offer both exceptional flexibility and high-temperature resistance.

Application of pectin hydrolyzing bacteria in tobacco to improve flue-cured tobacco quality

To study the relationship between the diversity of the surface microbial community and tobacco flavor, and to improve tobacco quality using microorganisms. The microbial community composition and diversity of 14 samples of flue-cured tobacco from tobacco-producing areas in Yunnan with varying grades were analyzed by high-throughput sequencing. PICRUSt was used for predicting microbial functions. A strain of Bacillus amyloliquefaciens W6-2 with the ability to degrade pectin was screened from the surface of flued-cured tobacco leaves from Yunnan reroasted tobacco leave. The enzyme preparation was prepared through fermentation and then applied for treating flue-cured tobacco. The improvement effect was evaluated by measuring the content of macromolecule and the changes in volatile components, combined with sensory evaluations. The bacterial communities on the surface of flue-cured tobacco exhibited functional diversity, consisting primarily of Variovorax, Pseudomonas, Sphingomonas, Burkholderia, and Bacillus. These bacterial strains played a role in the aging process of flue-cured tobacco leaves by participating in amino acid metabolism and carbohydrate metabolism. These metabolic activity converted complex macromolecules into smaller molecular compounds, ultimately influence the smoking quality and burning characteristics of flue-cured tobacco. The pectinase preparation produced through fermentation using W6-2 has been found to enhance the aroma and sweetness of flue-cured tobacco, leading to improved aroma, reduced impurities, and enhanced smoothness. Additionally, the levels of pectin, cellulose, and hemicellulose decreased, while the levels of water-soluble sugar and reducing sugar increased, and the contents of esters, ketones, and aldehydes increased, and the contents of benzoic acid decreased. The study revealed the correlation between surface microorganisms and volatile components of Yunnan tobacco leaves, and the enzyme produced by the pectin-degrading bacteria W6-2 effectively improved the quality of flue-cured tobacco.

Unraveling fluorescent mechanism of biomass-sourced carbon dots based on three major components: Cellulose, lignin, and protein

The complexity of biomass components leads to significant variations in the performance of biomass-based carbon dots (CDs). To shed light on this matter, this study presents a comparative analysis of the fluorescence properties of CDs using pure cellulose, lignin, and protein as models. Three CDs showed different fluorescent properties, resulting from the structure difference and carbonization behavior in the hydrothermal. The relatively gentle thermal degradation of proteins allows the macromolecular structure of amino acids to be preserved. This preservation results in a more regular lattice structure, a larger sp2 domain size, and N-doping, which contribute to the highest quantum yield (QY) of 8.7% of the CDs. In contrast, cellulose undergoes more severe thermal degradation with large amounts of small molecules generated, resulting in the CDs with fewer surface defects, more irregular lattice structures, and lower QY. These results provide a guideline for the design of carbon dots from different biomass.

Phase Inversion Gelation Process and Additive Effects on Hydrogel Film Properties of Cotton Cellulose

During the preparation of cotton cellulose hydrogels using the phase inversion gelation method of N,N-dimethylacetamide/LiCl solution under ethanol vapor, acetone (AC), methyl ethyl ketone (MEK), or diethyl ketone (DEK) were added as additives, and their gelation state and the properties of the resulting hydrogels were evaluated. Adding the ketones to the cellulose solution caused an increase in the gelation time, but the solution viscosity decreased, indicating that the cellulose tended to aggregate in the solution. Among the hydrogels prepared by adding ketones, the water content was as high as 2050%, especially for AC and MEK. In these hydrogels, cellulose formed an agglomerated fibrous network of a few micron widths, forming a tuft-like entrapment space of about 10 to 100 μm size. The structure surrounded water and held it in the hydrogels. The FTIR results showed that the water, which formed hydrogen bonds, was retained within the hydrogel network. This structural configuration was determined to be conducive to maintaining the gel state against external deformation forces, especially in the case of the addition of MEK.

A novel salt-barrier method of preparation flexible temperature resistant full-component nanocellulose membranes

With the simplification and diversification of separation technologies, nanocellulose membranes have become widely used as insulating materials. Recently, study of nanocellulose membrane modification has become a hot topic. However, the application of nanocellulose membrane has been limited due to their inadequate heat resistance and flexibility. Herein, based on the pyrolytic and thermoplastic properties of cellulose, we innovatively introduced a salt barrier scheme to regulate the degree of hydrogen bonding and thermoplastic bonding between fibers. This was achieved by adding a salt barrier agent, NaCl, in the middle of the nanocellulose to prepare and obtain flexible, high-temperature-resistant nanocellulose film materials. The full-component cellulose films thus prepared exhibited high tensile strength (8 MPa), excellent flexibility (105 mN), high electrical breakdown strength (67 KV/mm), and volume resistivity meeting the standard of insulation materials (3.23 × 1013 Ω·m). This scheme adheres to the principles of low cost, green, non-toxic and non-hazardous, providing a brand new approach for the research and development of high temperature resistant cellulose membrane materials, which is of significant commercial value and industrialization prospect.

Machine learning prediction of biochar yield based on biomass characteristics

Slow pyrolysis is a widely used thermochemical pathway that can convert organic waste into biochar. We employed six machine learning models to predictively model 13 selected variables using pearson feature selection. Additionally, partial dependence analysis is used to reveal the deep relationship between feature variables. Both the gradient boosting decision tree and the Levenberg-Marquardt backpropagation neural network achieved training set R2 > 0.9 and testing set R2 > 0.8. But the other models displayed lower performance on the testing set, with R2 < 0.8. The partial dependence plot demonstrates that pyrolysis conditions have greater impact on biochar yield than biomass composition. Furthermore, the highest treatment temperature, being the sole consistently changing feature, can serve as a guiding factor for regulating biochar yield. This study highlights the immense potential of machine learning in experimental prediction, providing a scientific reference for reducing time and economic costs in pyrolysis experiments and process development.

Co-pyrolysis of paper-laminated phenolic printed circuit boards and calcium-based additives in fixed and fluidized bed reactors

This study compares the impact of the calcium-based additives and the pyrolyzer on the recovery and the halide content of the oil produced from the pyrolysis of paper-laminated phenolic resin printed circuit boards (FR2-PCB). The preliminary experiments showed that the maximum liquid recovery (40.6%) was achieved in a fluidized bed pyrolyzer containing a 50:50 mixture of CaO and Ca(OH)2 operating at T = 620 °C and PCB-to-additive ratio (FR2/A) = 5.4 g/g for 22 min. Extra tests were then carried out under these conditions in fixed and fluidized bed pyrolyzers to separately explore the impact of CaO, Ca(OH)2, and CaO + Ca(OH)2 on the liquid recovery (LR) and the halogen content of the non-solid products. In the fluidized bed, LR in the presence of CaO, Ca(OH)2, and CaO + Ca(OH)2 was 34.5%, 41.2%, and 38.9 wt%, respectively. The fraction of phenolic compounds in the pyrolysis oil ranged from 86% to 93%, about 1-3% higher than the corresponding values in the fixed bed. Using additives led to lower halide content in the pyrolysis oil of the fluidized bed than that of the fixed bed. However, the opposite trend was observed in the absence of additives. Regardless of the type of pyrolyzer, Ca(OH)2 was more successful than CaO in increasing LR, whereas CaO was more effective than Ca(OH)2 in pyrolysis oil dechlorination. Co-pyrolysis of FR2-PCB and CaO + Ca(OH)2 in a fluidized bed reactor was identified as a practical approach to enhance the recovery of pyrolysis oil comprising only 5% of the original halogen content of the feedstock.

Cross-interaction of volatiles in fast co-pyrolysis of waste tyre and corn stover via TG-FTIR and rapid infrared heating techniques

Using fast infrared heating technology to minimize the pyrolysis temperature differential and optimizing secondary reactions is advantageous for studying co-pyrolysis behaviors. In this study, the co-pyrolysis behaviors of waste tyres (WT) and corn stover (CS), including product distribution, pyrolysis kinetics, and thermodynamics, were studied using TGA-FTIR analysis and fast infrared heating reactor. The DTG curves for the co-pyrolysis of WT and CS significantly differed from the calculated values, implying that the pyrolysis intermediates produced by CS during the pyrolysis process may have synergetic effects with the pyrolysis of WT. The apparent activation energies using the Kissinger-Akahira-Sunose (KAS) and Flynn-Wall-Ozawa (FWO) methods were similar, 244.88 kJ/mol and 245.93 kJ/mol, respectively. The experiment results suggest that the bio-oil yield increased first and then decreased with a further temperature increase. The yield of bio-oil gradually increased from 35.36% to 46.06% as temperature rose from 500 °C to 700 °C; but the further increasing to 800 °C decreased the bio-oil yield to 40.72%. The aromatic compounds in tar gradually increased with increasing the temperature, while the aliphatic compounds increased initially and then reduced. Meanwhile, the oxygenated compounds first decreased and then increased with increasing the pyrolysis temperature. The yield of light oil components (C＜10) increased from 5.11% at 400 °C to 7.71% at 700 °C. A further increase in the pyrolysis temperature to 800 °C reduced the light oil content to 4.93%.

Thermal degradation of Affinisol HPMC: Optimum Processing Temperatures for Hot Melt Extrusion and 3D Printing

PURPOSE

Affinisol HPMC HME is a new popular form of hypromellose specifically designed for the hot melt extrusion and 3D printing of pharmaceutical products. However, reports of its thermal stability include only data obtained under inert N2 atmosphere, which is not consistent with the common pharmaceutical practice. Therefore, detailed investigation of its real-life thermal stability in air is paramount for identification of potential risks and limitations during its high-temperature processing.

METHODS

In this work, the Affinisol HPMC HME 15LV powder as well as extruded filaments will be investigated by means of thermogravimetry, differential scanning calorimetry and infrared spectroscopy with respect to its thermal stability.

RESULTS

The decomposition in N2 was proceeded in accordance with the literature data and manufacturer's specifications: onset at ~260°C at 0.5°C·min-1, single-step mass loss of 90-95%. However, in laboratory or industrial practice, high-temperature processing is performed in the air, where oxidation-induced degradation drastically changes. The thermogravimetric mass loss in air proceeded in three stages: ~ 5% mass loss with onset at 150°C, ~ 70% mass loss at 200°C, and ~ 15% mass loss at 380°C. Diffusion of O2 into the Affinisol material was identified as the rate-determining step.

CONCLUSION

For extrusion temperatures ≥170°C, Affinisol exhibits a significant degree of degradation within the 5 min extruder retention time. Hot melt extrusion of pure Affinisol can be comfortably performed below this temperature. Utilization of plasticizers may be necessary for safe 3D printing.

Layer-by-Layer-Coated Cellulose Fibers Enable the Production of Porous, Flame-Retardant, and Lightweight Materials

New sustainable materials produced by green processing routes are required in order to meet the concepts of circular economy. The replacement of insulating materials comprising flammable synthetic polymers by bio-based materials represents a potential opportunity to achieve this task. In this paper, low-density and flame-retardant (FR) porous fiber networks are prepared by assembling Layer-by-Layer (LbL)-functionalized cellulose fibers by means of freeze-drying. The LbL coating, encompassing chitosan and sodium hexametaphosphate, enables the formation of a self-sustained porous structure by enhancing fiber-fiber interactions during the freeze-drying process. Fiber networks prepared from 3 Bi-Layer (BL)-coated fibers contain 80% wt of cellulose and can easily self-extinguish the flame during flammability tests in vertical configuration while displaying extremely low combustion rates in forced combustion tests. Smoke release is 1 order of magnitude lower than that of commercially available polyurethane foams. Such high FR efficiency is ascribed to the homogeneity of the deposited assembly, which produces a protective exoskeleton at the air/cellulose interface. The results reported in this paper represent an excellent opportunity for the development of fire-safe materials, encompassing natural components where sustainability and performance are maximized.

Interaction of the lignin-/cellulose-derived char with volatiles of varied origin: Part of the process for evolution of products in pyrolysis

The interaction between volatiles and homologous and/or heterologous char is almost inevitable during the transfer or diffusion of volatiles from inner core to outer surface of a biomass particle in pyrolysis. This shapes both composition of volatiles (bio-oil) and property of char. In this study, the potential interaction of lignin- and cellulose-derived volatiles with char of varied origin was investigated at 500 °C. The results indicated that both the lignin- and cellulose-char promoted polymerization of the lignin-derived phenolics, enhancing production of bio-oil by ca. 20%-30%, generating more heavy tar but suppressing gases formation, especially over cellulose-char. Conversely, the char catalysts, especially the heterologous lignin-char, promoted cracking of the cellulose-derivatives, producing more gases while less bio-oil and heavy organics. Additionally, the volatiles-char interaction also led to gasification of some organics and also aromatization of some organics on surface of char, resulting in enhanced crystallinity and thermostability of the used char catalyst, especially for the lignin-char. Moreover, the substance exchange and formation of carbon deposit also blocked pores and formed fragmented surface dotted with particulate matters in the used char catalysts.

Improved Light Hydrocarbon, Furans, and BTEX Production from the Catalytic Assisted Pyrolysis of Agave salmiana Bagasse over Silica Mesoporous Catalysts

The pyrolysis of the biomass Agave salmiana bagasse (10 K/min, ambient to 700 °C) was investigated in the absence and presence of Aerosil and MCM-41 catalysts. MCM-41 was synthetized using a typical hydrothermal method and characterized with XRD, SAXS, SEM, TEM, and nitrogen physisorption to confirm the presence of unidimensional 3.4 nm diameter pores. Pyrolysis products were monitored online with mass spectrometry (MS), analyzing the production of 29 different compounds, clustered in several groups, namely, olefins (ethene, 2-butene, 1,3-butadiene), oxygenated compounds (methanol, 2-methylbutanol, acetic acid), furan derivatives (furan, furfural, 2-methylfurane), and aromatic compounds (BTEX). Complete decomposition of the cellulose and hemicellulose content of the biomass was observed at temperatures below 400 °C. Lignin decomposition was completed by 550 °C. Catalyst-assisted pyrolysis showed reduced acetic acid and methanol formation with Aerosil and MCM-41. The use of Aerosil does not affect the overall production of olefins, yet increases benzene yield, while reducing the production of phenol, furan, and furan derivatives. With MCM-41, there is increased production of olefins, furan, furan derivatives, cyclohexanone and BTEX, yet phenol production is decreased. At temperatures below 400 °C, the product formation pattern is comparable to non-catalytic pyrolysis.

Direct CO2 Capture by Alkali-Dissolved Cellulose and Sequestration in Building Materials and Artificial Reef Structures

Current carbon capture and utilization (CCU) technologies require high energy input and costly catalysts. Here, an effective pathway is offered that addresses climate action by atmospheric CO₂ sequestration. Industrially relevant highly reactive alkali cellulose solutions are used as CO₂ absorption media. The latter lead to mineralized cellulose materials (MCM) at a tailorable cellulose-to-mineral ratio, forming organic-inorganic viscous systems (viscosity from 10² to 10⁷  mPa s and storage modulus from 10 to 10⁵  Pa). CO₂ absorption and conversion into calcium carbonate and associated minerals translate to maximum absorption of 6.5 gCO₂ g_cellulose ^-1 , tracking inversely with cellulose loading. Cellulose lean gels are easily converted into dry powders, shown as a functional component of ceramic glazes and cementitious composites. Meanwhile, cellulose-rich gels are moldable and extrudable, yielding stone-like structures tested as artificial substrates for coral reef restoration. Life Cycle Assessment (LCA) suggests new CCU opportunities for building materials, as demonstrated in underwater deployment for coral reef ecosystem restoration.

Preparation of biochar derived from waste cotton woven by low-dosage Fe(NO3)3 activation: characterization, pore development, and adsorption

Currently, researchers are looking for efficient and sustainable methods to synthesize biochar for the adsorption of pollutants. In this study, biochar with high specific surface area, tunable pore structure, and abundant functional groups were prepared from waste cotton woven (WCW) using low-dosage Fe(NO₃)₃ activation at 400-900 °C. The biochar obtained at 800 °C possessed the excellent specific surface area of 1167.37 m²/g with a unique micro-mesoporous structure. XRD analysis showed that the Fe species changed from Fe₂O₃ to Fe₃O₄ and then Fe⁰ with the increase of pyrolysis temperature. TEM images further confirmed the template effect of iron oxides for mesoporous formation. The effect of Fe(NO₃)₃ on the pyrolysis pathway of waste cotton woven was systematically investigated by TG and XPS analyses to explore the pore development of biochar. The results indicated that Fe(NO₃)₃ could enhance the dehydration, decarbonylation and dehydroxylation of WCW components, thereby reducing the temperature required for WCW pyrolysis. Moreover, the synergistic effect of Fe and N species improved the development of microporous and mesoporous structure through carbon structure corrosion and reorganization, and volatile release. Additionally, satisfactory adsorption capacity for Eriochrome Black T (456.01 mg/g) of the prepared biochar was obtained at 25 °C. This study demonstrated that low-dosage Fe(NO₃)₃ activation of waste cotton woven could be used as a facile method to prepare promising inexpensive biochar for contaminants removal.

Amorphous silica fiber matrix biomaterials: An analysis of material synthesis and characterization for tissue engineering

Silica biomaterials including Bioglass offer great biocompatibility and bioactivity but fail to provide pore and degradation features needed for tissue engineering. Herein we report on the synthesis and characterization of novel amorphous silica fiber matrices to overcome these limitations. Amorphous silica fibers were fused by sintering to produce porous matrices. The effects of sacrificial polymer additives such as polyvinyl alcohol (PVA) and cellulose fibers (CF) on the sintering process were also studied. The resulting matrices formed between sintering temperatures of 1,350–1,550 °C retained their fiber structures. The matrices presented pores in the range of 50–200 μm while higher sintering temperatures resulted in increased pore diameter. PVA addition to silica significantly reduced the pore diameter and porosity compared with silica matrices with or without the addition of CF. The PVA additive morphologically appeared to fuse the silica fibers to a greater extent and resulted in significantly higher compressive modulus and strength than the rest of the matrices synthesized. These matrices lost roughly 30% of their original mass in an in vitro degradation study over 40 weeks. All matrices absorbed 500 wt% of water and did not change in their overall morphology, size, or shape with hydration. These fiber matrices supported human mesenchymal stem cell adhesion, proliferation, and mineralized matrix production. Amorphous silica fiber biomaterials/matrices reported here are biodegradable and porous and closely resemble the native extracellular matrix structure and water absorption capacity. Extending the methodology reported here to alter matrix properties may lead to a variety of tissue engineering, implant, and drug delivery applications.

Current Challenges and Perspectives for the Catalytic Pyrolysis of Lignocellulosic Biomass to High-Value Products

Lignocellulosic biomass is an excellent alternative of fossil source because it is low-cost, plentiful and environmentally friendly, and it can be transformed into biogas, bio-oil and biochar through pyrolysis; thereby, the three types of pyrolytic products can be upgraded or improved to satisfy the standard of biofuel, chemicals and energy materials for industries. The bio-oil derived from direct pyrolysis shows some disadvantages: high contents of oxygenates, water and acids, easy-aging and so forth, which restrict the large-scale application and commercialization of bio-oil. Catalytic pyrolysis favors the refinement of bio-oil through deoxygenation, cracking, decarboxylation, decarbonylation reactions and so on, which could occur on the specified reaction sites. Therefore, the catalytic pyrolysis of lignocellulosic biomass is a promising approach for the production of high quality and renewable biofuels. This review gives information about the factors which might determine the catalytic pyrolysis output, including the properties of biomass, operational parameters of catalytic pyrolysis and different types of pyrolysis equipment. Catalysts used in recent research studies aiming to explore the catalytic pyrolysis conversion of biomass to high quality bio-oil or chemicals are discussed, and the current challenges and future perspectives for biomass catalytic pyrolysis are highlighted for further comprehension.

Critical Review of the Recent Literature on Organic Byproducts in E-Cigarette Aerosol Emissions

We review the literature on laboratory studies quantifying the production of potentially toxic organic byproducts (carbonyls, carbon monoxide, free radicals and some nontargeted compounds) in e-cigarette (EC) aerosol emissions, focusing on the consistency between their experimental design and a realistic usage of the devices, as determined by the power ranges of an optimal regime fulfilling a thermodynamically efficient process of aerosol generation that avoids overheating and "dry puffs". The majority of the reviewed studies failed in various degrees to comply with this consistency criterion or supplied insufficient information to verify it. Consequently, most of the experimental outcomes and risk assessments are either partially or totally unreliable and/or of various degrees of questionable relevance to end users. Studies testing the devices under reasonable approximation to realistic conditions detected levels of all organic byproducts that are either negligible or orders of magnitude lower than in tobacco smoke. Our review reinforces the pressing need to update and improve current laboratory standards by an appropriate selection of testing parameters and the logistical incorporation of end users in the experimental design.

Reactive Flame-Retardant Cotton Fabric Coating: Combustion Behavior, Durability, and Enhanced Retardant Mechanism with Ion Transfer

In recent years, we have witnessed numerous indoor fires caused by the flammable properties of cotton. Flame-retardant cotton deserves our attention. A novel boric acid and diethylenetriaminepenta (methylene-phosphonic acid) (DTPMPA) ammonium salt-based chelating coordination flame retardant (BDA) was successfully prepared for cotton fabrics, and a related retardant mechanism with ion transfer was investigated. BDA can form a stable chemical and coordination bond on the surface of cotton fibers by a simple three-curing finishing process. The limiting oxygen index (LOI) value of BDA-90 increased to 36.1%, and the LOI value of cotton fabric became 30.3% after 50 laundering cycles (LCs) and exhibited excellent durable flame retardancy. Fourier-transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM) methods were used to observe the bonding mode and morphology of BDA on cotton fibers. A synergistic flame-retardant mechanism of condensed and gas phases was concluded from thermogravimetry (TG), cone calorimeter tests, and TG-FTIR. The test results of whiteness and tensile strength showed that the physical properties of BDA-treated cotton fabric were well maintained.

Algorithmic Explorations of Unimolecular and Bimolecular Reaction Spaces

Algorithmic reaction exploration based on transition state searches has already made inroads into many niche applications, but its potential as a general-purpose tool is still largely unrealized. Computational cost and the absence of benchmark problems involving larger molecules remain obstacles to further progress. Here an ultra-low cost exploration algorithm is implemented and used to explore the reactivity of unimolecular and bimolecular reactants, comprising a total of 581 reactions involving 51 distinct reactants. The algorithm discovers all established reaction pathways, where such comparisons are possible, while also revealing a much richer reactivity landscape, including lower barrier reaction pathways and a strong dependence of reaction conformation in the apparent barriers of the reported reactions. The diversity of these benchmarks illustrate that reaction exploration algorithms are approaching general-purpose capability.

Biochar colloids facilitate transport and transformation of Cr(VI) in soil: Active site competition coupling with reduction reaction

Biochar has been demonstrated as an efficient amendment for immobilizing contaminants. However, a certain number of micro/nano-scale particles are inevitably present in the fresh or aged biochar, which may facilitate the downward transport of contaminants along the soil profile, posing a detrimental impact on the groundwater. Herein, the effects of biochar colloids derived from wood chip and wheat straw at two temperatures (350 °C and 500 °C) on the transport and transformation of Cr(VI) in soil were investigated. All biochar colloids facilitated the transport of Cr(VI) in a loam clay Ultisol, which was attributed to the competition between biochar colloids and Cr(VI) for the available sorption sites on the soil surface. Wheat straw biochar colloids caused more transport of Cr(VI) than wood chip ones due to the more negative charge and higher polarity, which resulted in stronger electrostatic repulsion and competition with Cr(VI). It is soluble Cr(VI) that dominated the transport of Cr in the effluent solution, however, the particulate Cr(VI) could be reduced into Cr(III) before being carried by biochar colloids for co-transport. The 350 °C biochar colloids had higher electron donating capacities than 500 °C ones, resulting in more reduction of Cr(VI) and more co-transport as biochar colloids-associated Cr(III) in the effluent. Moreover, the more negatively charged 350 °C biochar colloids could also attach more soil Fe oxides, further facilitating the cotransport of Cr via the formation of a binary or ternary complex. Modeling showed the experimental-consistently results that biochar colloids caused 0.5-7.0 times faster transport of Cr(VI) than no biochar colloids in the long-term period. Our findings demonstrate that biochar colloids can enhance transport and transformation of Cr(VI) in soils, which arouse migration risk concern about in-situ remediation of Cr(VI)-contaminated soils by biochar.

Effect of pretreatment with Phanerochaete chrysosporium on physicochemical properties and pyrolysis behaviors of corn stover

Fungal pretreatment can selectively degrade partial biomass components, which undoubtedly exerts a significant influence on biomass pyrolysis behavior. The corn stover was pretreated with Phanerochaete chrysosporium, and its influence on the physicochemical properties and pyrolysis behaviors of biomass together with the product characteristics were investigated. The Phanerochaete chrysosporium was more active to degrade hemicellulose and lignin. The hemicellulose and lignin contents in corn stover were decreased by 35.14 % and 31.80 %, respectively, after five weeks pretreatment, compared to the untreated sample. The reaction activation energy decreased from 52.89 kJ·mol^-1 for the untreated sample to 40.88 kJ·mol^-1 for the sample pretreated for five weeks. The Phanerochaete chrysosporium pretreatment was beneficial to the biochar production but exerted an unfavorable effect on the texture structure. The Phanerochaete chrysosporium also had an obvious influence on the bio-oil compositions. This study can provide a scientific reference for the application of biological pretreatment for biomass pyrolysis technology.

Applications of Hydrochar and Charcoal in the Iron and Steelmaking Industry—Part 1: Characterization of Carbonaceous Materials

The iron and steelmaking industry faces the dilemma of the need to decrease their greenhouse gas emissions to align with decarbonization goals, while at the same time fulfill the increasing steel demand from the growing population. Replacing fossil coal and coke with biomass-based carbon materials reduces the net carbon dioxide emissions. However, there is currently a shortage of charcoal to fully cover the demand from the iron and steelmaking industry to achieve the emission-reduction goals. Moreover, the transportation and energy sectors can compete for biofuel usage in the next few decades. Simultaneously, our society faces challenges of accumulation of wastes, especially wet organic wastes that are currently not reused and recycled to their full potentials. Here, hydrothermal carbonization is a technology which can convert organic feedstocks with high moisture contents to solid fuels (hydrochar, one type of biochar) as an alternative renewable carbon material. This work studied the differences between a hydrochar, produced from lemon peels (Lemon Hydrochar), and two types of charcoals (with and without densification) and an Anthracite coal. Characterizations such as chemical and ash compositions, thermogravimetric analyses in nitrogen and carbon dioxide atmospheres, scanning electron microscope analyses of carbon surface morphologies, and pyrolysis up to 1200 °C were performed. The main conclusions from this study are the following: (1) hydrochar has a lower thermal stability and a higher reactivity compared to charcoal and Anthracite; (2) densification resulted in a reduction of the moisture pickup and CO2 reactivity of charcoal; (3) pyrolysis of Lemon Hydrochar resulted in the formation of a large amount of tar (17 wt%) and gas (39 wt%), leading to its low fixed carbon content (27 wt%); (4) a pyrolyzed hydrochar (up to 1200 °C) has a comparable higher heating value to those of charcoal and Anthracite, but its phosphorous, ash, and alkalis contents increased significantly; (5) based on the preliminary assessment, hydrochar should be blended with charcoal or Anthracite, or be upgraded through slow pyrolysis to fulfill the basic functions of carbon in the high-temperature metallurgical processes.

Biomass Behavior upon Fast Pyrolysis in Inert and in CO2-Rich Atmospheres: Role of Lignin, Hemicellulose and Cellulose Content

The present work focuses on the quality of char and primary tar produced from fast pyrolysis in N2 and CO2 of lignocellulosic biomasses: walnut shells (lignin-rich), straw (hemicellulose-rich) and pinewood (cellulose-rich). Heat treatments are carried out in a heated strip reactor (HSR) at 1573 and 2073 K for 3 s, with a heating rate of 104 K/s. The equipment allows for quenching the volatiles as soon as they are emitted. Chars are analyzed by thermogravimetric analysis in air. Results are compared with the products obtained from raw lignin, pure cellulose and pure hemicellulose. Cellulose and hemicellulose tars are dominated by anhydrous monosaccharides, which are scarce in straw tar and abundant in walnut shells tar. Polycyclic aromatic hydrocarbons PAHs are present in the primary products, in particular for walnut shells. The most reactive char is the one obtained from straw and the least reactive is the walnut shells char. Severe heat treatment and a CO2 atmosphere generate additional char components with higher and lower reactivity. The more reactive char component may arise from cross-linking reactions involving the monosaccharides (for which the result decreased in tar), whereas the less reactive component arises from thermal annealing and graphitization. Thus, the pyrolytic behavior of biomasses cannot be reconstructed with a mere addition of the lignin/cellulose/hemicellulose contribution, taking into account their content in the biomass.

Effects of torrefaction on product distribution and quality of bio-oil from food waste pyrolysis in N2 and CO2

Waste food utilization to produce bio-oil through pyrolysis has received increasing attention. The feedstock can be utilized more efficiently as its properties are upgraded. In this work, the mixed food waste (MFW) was pretreated via torrefaction at moderate temperatures (250-275 °C) under an inert atmosphere before fast pyrolysis. The pyrolysis of torrified MFW (T-MFW) was performed in a bubbling fluidized-bed reactor (FBR) to study the influence of torrefaction on the pyrolysis product distribution and bio-oil compositions. The highest liquid yield of 39.54 wt% was observed at a pyrolysis temperature of 450℃. The torrefaction has a significant effect on the pyrolysis process of MFW. After torrefaction, the higher heating values (HHVs) of the pyrolysis bio-oils (POs) ranged from 31.51 to 34.34 MJ/kg, which were higher than those of bio-oils from raw MFW (27.69-31.58 MJ/kg). The POs mainly contained aliphatic hydrocarbons (alkenes and ketones), phenolic, and N-containing derivatives. The pyrolysis of T-MFW was also carried out under the CO2 atmosphere. The application of CO2 as a carrier gas resulted in a decrease in the liquid yield and an increase in the gas product yield. In addition, the carbon and nitrogen content of POs increased, whereas the oxygen was reduced via the release of moisture and CO. Using CO2 in pyrolysis inhibited the generation of nitriles derivatives in POs, which are harmful to the environment. These results indicated that the application of CO2 to the thermal treatment of T-MFW could be feasible in energy production as well as environmental pollution control.

Valorization of a Pyrolytic Aqueous Condensate and Its Main Components for L-Malic Acid Production with Aspergillus oryzae DSM 1863

Pyrolytic aqueous condensate (PAC) might serve as a cost-effective substrate for microbial malic acid production, as it is an unused side stream of the fast pyrolysis of lignocellulosic biomass that contains acetol and acetate as potential carbon sources. In the present study, shake flask cultures were performed to evaluate the suitability of acetol and its combination with acetate as substrates for growth and L-malate production with the filamentous fungus Aspergillus oryzae. Acetol concentrations of up to 40 g/L were shown to be utilized for fungal growth. In combination with acetate, co-metabolization of both substrates for biomass and malate formation was observed, although the maximum tolerated acetol concentration decreased to 20 g/L. Furthermore, malate production on PAC detoxified by a combination of rotary evaporation, overliming and activated carbon treatment was studied. In shake flasks, cultivation using 100% PAC resulted in the production of 3.37 ± 0.61 g/L malate, which was considerably improved by pH adjustment up to 9.77 ± 0.55 g/L. A successful scale-up to 0.5-L bioreactors was conducted, achieving comparable yields and productivities to the shake flask cultures. Accordingly, fungal malate production using PAC was successfully demonstrated, paving the way for a bio-based production of the acid.

Thermochemical Conversion of Untreated and Pretreated Biomass for Efficient Production of Levoglucosenone and 5-Chloromethylfurfural in the Presence of an Acid Catalyst

Levoglucosenone (LGO) and 5-chloromethyl furfural (5-CMF) are two bio-based platform chemicals with applications in medicines, green solvents, fuels, and the polymer industry. This study demonstrates the one-step thermochemical conversion of raw and pretreated (delignified) biomass to highly-valuable two platform chemicals in a fluidized bed reactor. Hydrochloric acid gas is utilized to convert biomass thermochemically. The addition of hydrochloric acid gas facilitates the formation of LGO and CMF. Acid gas reacts with biomass to form 5-CMF, which acts as a catalyst to increase the concentration of LGO in the resulting bio-oil. The presence of higher cellulose content in delignified biomass significantly boosts the synthesis of both platform chemicals (LGO and CMF). GC-MS analysis was used to determine the chemical composition of bio-oil produced from thermal and thermochemical conversion of biomass. At 350 °C, the maximum concentration of LGO (27.70 mg/mL of bio-oil) was achieved, whereas at 400 °C, the highest concentration of CMF (19.24 mg/mL of bio-oil) was obtained from hardwood-delignified biomass. The findings suggest that 350 °C is the optimal temperature for producing LGO and 400 °C is optimal for producing CMF from delignified biomass. The secondary cracking process is accelerated by temperatures over 400 °C, resulting in a low concentration of the target platform chemicals. This work reveals the simultaneous generation of LGO and CMF, two high-value commercially relevant biobased compounds.

A comprehensive investigation on cellulose nanocrystals with different crystal structures from cotton via an efficient route

The crystal structures of cellulose nanomaterials play an important role in their morphologies and applications, however, there was still lacking systematic research on preparing various crystalline allomorphs of cellulose nanocrystals with high thermal stability. Herein, the efficient synthesis route was presented to design various crystalline allomorphs of cellulose from cotton. And then, cellulose nanocrystals with different crystal structures (CNC-I, CNC-II, CNC-III_II, CNC-IV_II) were prepared by hydrogen peroxide hydrolysis of resultant cellulose. Overall, needle-like CNC-I (length of 180 ± 25 nm, diameter of 12 ± 2 nm), near-spherical CNC-II (diameter of 101 ± 12 nm), and spherical CNC-III_II (diameter of 22 ± 3 nm) and CNC-IV_II (diameter of 21 ± 2 nm) all exhibited remarkable dispersibility and thermal stability (T_max > 357 °C). This work provides a simple and low-cost synthesis route for various crystalline allomorphs of CNCs with high thermal stability from the same raw materials (cotton).

A Low-Temperature Dehydration Carbon-Fixation Strategy for Lignocellulose-Based Hierarchical Porous Carbon for Supercapacitors

Lignocellulose-based hierarchical porous carbon is a very promising electrode material for supercapacitors, but lower volumetric energy density and yield have hindered its practical applications. Herein, a low-temperature dehydration carbon-fixation method using NH₄ Cl as modification reagent was developed to prepare rice husk-based hierarchical porous carbon (RHPC) with high volumetric performance and yield. The RHPC-N electrode exhibited a higher volumetric specific capacitance of 134.4 F cm^-3 than that of the RHPC electrode (98.4 F cm^-3 ) in 1 m Et₄ NBF₄ /propylene carbonate electrolyte. The volumetric energy density (28.8 Wh L^-1 ) of the RHPC-N electrode was 37.1 % higher than that of the RHPC electrode (21.0 Wh L^-1 ), which greatly enhanced the practical application potential of RHPC in supercapacitors. Moreover, the yield of RHPC increased 1.2 times by this method, which greatly improved the production capacity and reduced the cost. This research establishes a simple and highly efficient method to improve the volumetric energy density and the yield of lignocellulose-based hierarchical porous carbon.

Recovery, separation and production of fuel, plastic and aluminum from the Tetra PAK waste to hydrothermal and pyrolysis processes

The establishment of a method of separation of materials from Tetra Pak waste to obtain products for use as raw material, fuel or other purposes was investigated in this study. First, the feasibility of hydrothermal treatment for the production of a solid fuel (hydrochar) and solid fraction formed by polyethylene and aluminum, called composite was analyzed. The results indicated that hydrothermal treatment performed at 240 °C yield the formation of hydrochar with good properties for its use as fuel and a composite of polyethylene and aluminum. The best conversion and separation of the cardboard and polyethylene/aluminum were obtained using 120 min as operating time. Then, the recovery of the aluminum fraction from the composite by using spent olive oil waste was studied. A partial separation of the composite layers (polyethylene and aluminum) was accomplished with improved aluminum purity for higher operating temperatures. Finally, the operating conditions of the pyrolysis process for the production of a solid (char) and high purity composite (aluminum) were optimized. The characterization results indicated that both char and aluminum resulting from the pyrolysis of the Tetra Pak at 400 °C still have a significant amount of polyethylene while higher purity levels of aluminum can be obtained at temperatures equal of higher than 500 °C.

Pyrolytic activation of cellulose: Energetics and condensed phase effects

Bottom-up design of lignocellulose pyrolysis to optimize the quality and yield of bio-oil is hindered by the limited knowledge of the underlying condensed phase biomass chemistry. The influence of condensed...

Lignocellulosic biomass-based pyrolysis: A comprehensive review

The efficacious application of lignocellulosic biomass for the new valuable chemicals generation curbs the excessive dependency on fossil fuels. Among the various techniques available, pyrolysis has garnered much attention for conversion of lignocellulosic biomass (encompasses cellulose, hemicellulose and lignin components) into product of solid, liquid and gases by thermal decomposition in an efficient manner. Pyrolysis conversion mechanism can be outlined as formation of char, depolymerisation, fragmentation and other secondary reactions. This paper gives a deep insight about the pyrolytic behavior of the lignocellulosic components accompanied by its by-products. Also several parameters such as reaction environment, temperature, residence time and heating rate which has a great impact on the pyrolysis process are also elucidated in a detailed manner. In addition the environmental and economical facet of lignocellulosic biomass pyrolysis for commercialization at industrial scale is critically analyzed. This article also illustrates the prevailing challenges and inhibition in implementing lignocellulosic biomass based pyrolysis with possible solution.

Co-hydrothermal carbonization of swine manure and cellulose: Influence of mutual interaction of intermediates on properties of the products

Co-hydrothermal carbonization (HTC) of livestock manure and biomass might improve the fuel properties of the hydrochar due to the high reactivity of the biomass-derived intermediates with the abundant oxygen-containing functionalities. However, the complicated compositions make it difficult to explicit the specific roles of the individual components of biomass played in the co-HTC process. In this study, cellulose was used for co-HTC with swine manure to investigate the influence on the properties of the hydrochar. The yield of hydrochar obtained from co-HTC reduced gradually with the cellulose proportion increased, and the solid yield was lower than the theoretical value. This was because the cellulose-derived intermediates favored the stability of the fragments from hydrolysis of swine manure. The increased temperature resulted in the reduction of the hydrochar yield whereas the prolonged time enhanced the formation of solid product. The interaction of the co-HTC intermediates facilitated the formation of O-containing species, thus making the solid more oxygen- and hydrogen-rich with a higher volatility. In addition, the co-HTC affected the evolution of functionalities like -OH and CO during the thermal treatment of the hydrochar and altered its morphology by stuffing the pores from swine manure-derived solid with the microspheres from HTC of cellulose. The interaction of the varied intermediates also impacted the formation of amines, ketones, carboxylic acids, esters, aromatics and the polymeric products in distinct ways.

Prediction of pyrolyzate yields by response surface methodology: A case study of cellulose and polyethylene co-pyrolysis

There are numerous combinations of biomass, plastic, and co-pyrolysis conditions. The presence of synergies, which make pyrolyzate distribution more complex, has been supported by research. In this study, the potential of response surface methodology (RSM) to predict the pyrolyzate yields affected by synergies during co-pyrolysis (500-700 °C) of cellulose and polyethylene was investigated, beyond gas, oil, and char yields. The results indicated that co-pyrolysis promoted liquid and C_5-28 hydrocarbon production with increasing temperature. The quadratic model could predict the total gas, CO, CO₂, and liquid yields, including the synergy. The cubic model could predict the levoglucosan and C_5-28 hydrocarbon yields due to various synergies under different conditions. The linear model was suitable for the char yield distribution without interaction. Thus, this study reveals that RSM has a significant potential to predict pyrolyzate yields, enabling co-pyrolysis condition setting to maximize the desired product recovery with the fewest experiments.

Fast pyrolysis of holocellulose for the preparation of long-chain ether fuel precursors: Effect of holocellulose types

The pyrolysis behaviors of nine biomass-derived holocelluloses (from seven agricultural and two forestry residues) were studied on a thermogravimetric analyzer (TGA) and pyrolysis-gas chromatography/mass spectrometer (Py-GC/MS). The results illustrated that compared with forestry holocellulose, agricultural holocellulose had quite high ash and hemicellulose contents. Moreover, agricultural holocellulose presented lower initial temperature and maximum mass loss rate. The results of GC/MS revealed that agricultural holocellulose produced more acids, ketones, aldehydes and furans and corn stalk holocellulose led to the highest targeted compounds (ketones, aldehydes and furans with carbonyl group) content of 51.4%. Woody holocellulose was suitable for the production of sugars, particularly levoglucosan, and pine sawdust holocellulose afforded the highest levoglucosan content of 46.55%. Intriguingly, the correlation of sugars/levoglucosan content with a mass ratio of cellulose to hemicellulose (CE/HCE) was put forward.

Lignin-phenol monomers govern the pyrolytic conversion of natural biomass from lignocellulose to products

The effect of the interaction between lignin-phenol monomers and holocellulose in natural biomass on the distribution of pyrolysis products remains unknown. The results of this study showed that the interaction between lignin and holocellulose during the pyrolysis of natural biomass became more pronounced as the pyrolysis temperature increased. The interaction between lignin and holocellulose in the natural crosslinked structure promoted the generation of CO and inhibited the generation of CO₂ at 750 °C. Lignin inhibited the decarboxylic reaction of hemicellulose during pyrolysis but was important for the generation of levoglucosan during cellulose pyrolysis. Holocellulose slowed the demethoxyreaction of lignin guaiacol but promoted the removal of aliphatic hydrocarbon substituents from the aromatic ring. The cinnamyl phenol monomers of lignin increased the rates of change of biomass pyrolysis products with the lignin mass fraction at 400 °C. However, when the pyrolysis temperature increased to 750 °C, all types of lignin phenol monomers increased the rates of change of the biomass pyrolysis products. Our results provide new insights that have implications for the development of pyrolysis techniques for the resource recycling of various types of biomass for the preparation of high-grade gaseous and liquid fuels.

Valorization of sorghum distillery residue to produce bioethanol for pollution mitigation and circular economy

This research aims to study the wet torrefaction (WT) and saccharification of sorghum distillery residue (SDR) towards hydrochar and bioethanol production. The experiments are designed by Box-Behnken design from response surface methodology where the operating conditions include sulfuric acid concentration (0, 0.01, and 0.02 M), amyloglucosidase concentration (36, 51, and 66 IU), and saccharification time (120, 180, and 240 min). Compared to conventional dry torrefaction, the hydrochar yield is between 13.24 and 14.73%, which is much lower than dry torrefaction biochar (yield >50%). The calorific value of the raw SDR is 17.15 MJ/kg, which is significantly enhanced to 22.36-23.37 MJ/kg after WT. When the sulfuric acid concentration increases from 0 to 0.02 M, the glucose concentration in the product increases from 5.59 g/L to 13.05 g/L. The prediction of analysis of variance suggests that the best combination to maximum glucose production is 0.02 M H₂SO₄, 66 IU enzyme concentration, and 120 min saccharification time, and the glucose concentration is 30.85 g/L. The maximum bioethanol concentration of 19.21 g/L is obtained, which is higher than those from wheat straw (18.1 g/L) and sweet sorghum residue (16.2 g/L). A large amount of SDR is generated in the kaoliang liquor production process, which may cause environmental problems if it is not appropriately treated. This study fulfills SDR valorization for hydrochar and bioenergy to lower environmental pollution and even achieve a circular economy.

COVID-19 mask waste to energy via thermochemical pathway: Effect of Co-Feeding food waste

In this study, co-pyrolysis of single-use face mask (for the protection against COVID-19) and food waste was investigated for the purpose of energy and resource valorization of the waste materials. To this end, disposable face mask (a piece of personal protective equipment) was pyrolyzed to produce fuel-range chemicals. The pyrolytic gas evolved from the pyrolysis of the single-use face mask consisted primarily of non-condensable permanent hydrocarbons such as CH₄, C₂H₄, C₂H₆, C₃H₆, and C₃H₈. An increase in pyrolysis temperature enhanced the non-condensable hydrocarbon yields. The pyrolytic gas had a HHV of >40 MJ kg^-1. In addition, hydrocarbons with wider carbon number ranges (e.g., gasoline-, jet fuel-, diesel-, and motor oil-range hydrocarbons) were produced in the pyrolysis of the disposable face mask. The yields of the gasoline-, jet fuel-, and diesel-range hydrocarbons obtained from the single-use mask were highest at 973 K. The pyrolysis of the single-use face mask yielded 14.7 wt% gasoline-, 18.4 wt% jet fuel-, 34.1 wt% diesel-, and 18.1 wt% motor oil-range hydrocarbons. No solid char was produced via the pyrolysis of the disposable face mask. The addition of food waste to the pyrolysis feedstock led to the formation of char, but the presence of the single-use face mask did not affect the properties and energy content of the char. More H₂ and less hydrocarbons were produced by co-feeding food waste in the pyrolysis of the disposable face mask. The results of this study can contribute to thermochemical management and utilization of everyday waste as a source of energy.

Biomass Fast Pyrolysis Vapor Upgrading over γ-Alumina, Hydrotalcite, Dolomite and Effect of Na2CO3 Loading: A Pyro Probe GCMS Study

The influence of γ-alumina, hydrotalcite, dolomite and Na2CO3 loaded γ-alumina, hydrotalcite, dolomite on fast pyrolysis vapor upgrading of beechwood was investigated using an analytical pyro probe-gas chromatography/mass spectrometry instrument (Py-GC/MS) at a temperature of 500 °C. Overall, this research showcased that these catalysts can deoxygenate biomass pyrolysis vapors into a mixture of intermediate compounds which have substantially lower oxygen content. The intermediate compounds are deemed to be suitable for downstream hydrodeoxygenation processes and it also means that hydrogen consumption will be reduced as a result of moderate in-situ deoxygenation. Among the support catalysts, the application of hydrotalcite yielded the best results with the formation of moderately deoxygenated compounds such as light phenols, mono-oxy ketones, light furans and hydrocarbons with a TIC area % of 7.5, 44.8, 9.8 and 9.8, respectively. In addition, acids were considerably reduced. Dolomite was the next most effective catalyst as γ-alumina retained most of the acids and other oxygenates. Na2CO3 loading on γ-alumina had a noticeable effect on eliminating more or less all the acids, enhancing the mono-oxy-ketones and producing lighter furans. In contrast, Na2CO3 loading on dolomite and hydrotalcite did not show a major impact on the composition except for further enhancing the mono-oxy-ketones (e.g., acetone and cyclopentenones). Additionally, in the case of hydrotalcite and γ-alumina, Na2CO3 loading suppressed the formation of hydrocarbons. In this research, the composition of pyrolytic vapors as a result of catalysis is elaborated further under the specific oxygenate groups such as acids, phenolics, furanics, ketones and acids. Further the catalysts were also characterized by BET, XRD and TGA analysis.

Single-Use Disposable Waste Upcycling via Thermochemical Conversion Pathway

Herein, the pyrolysis of two types of single-use disposable waste (single-use food containers and corrugated fiberboard) was investigated as an approach to cleanly dispose of municipal solid waste, including plastic waste. For the pyrolysis of single-use food containers or corrugated fiberboard, an increase in temperature tended to increase the yield of pyrolytic gas (i.e., non-condensable gases) and decrease the yield of pyrolytic liquid (i.e., a mixture of condensable compounds) and solid residue. The single-use food container-derived pyrolytic product was largely composed of hydrocarbons with a wide range of carbon numbers from C₁ to C₃₂, while the corrugated fiberboard-derived pyrolytic product was composed of a variety of chemical groups such as phenolic compounds, polycyclic aromatic compounds, and oxygenates involving alcohols, acids, aldehydes, ketones, acetates, and esters. Changes in the pyrolysis temperature from 500 °C to 900 °C had no significant effect on the selectivity toward each chemical group found in the pyrolytic liquid derived from either the single-use food containers or corrugated fiberboard. The co-pyrolysis of the single-use food containers and corrugated fiberboard led to 6 times higher hydrogen (H₂) selectivity than the pyrolysis of the single-use food containers only. Furthermore, the co-pyrolysis did not form phenolic compounds or polycyclic aromatic compounds that are hazardous environmental pollutants (0% selectivity), indicating that the co-pyrolysis process is an eco-friendly method to treat single-use disposable waste.

A highly efficient chemical approach to producing green phosphorylated cellulosic macromolecules

The introduction of phosphate groups into cellulosic fibers allows for the tuning of their fire resistance, chelating and metal-adhesion properties, enabling the development of flame-retardant adhesive and adsorbent materials. Toward that end, the major challenge is developing a novel efficient and environmentally friendly phosphorylation route that offers an alternative to existing methods, which can achieve the targeted properties. For this purpose, cellulosic fibers were chemically modified herein using solid-state phosphorylation with phosphoric acid and urea without causing substantial damage to the fibers. The morphological, physicochemical, structural and thermal characterisations were examined using FQA, SEM, EDX, FTIR, ¹³C/³¹P NMR, conductometric titration, zeta potential measurement and thermogravimetric analysis. All the characterisations converge towards a crosslinked polyanion structure, with about 20 wt% grafted phosphates, a nitrogen content of about 5 wt% and a very high charge density of 6608 mmol kg⁻¹. Phosphate groups are linked to cellulose through a P–O–C bond in the form of orthophosphate and pyrophosphates. Furthermore, thermal properties of the phosphorylated cellulosic fibers were investigated and a new degradation mechanism was proposed.

The introduction of phosphate groups into cellulosic fibers allows for the tuning of their fire resistance, chelating and metal-adhesion properties, enabling the development of flame-retardant adhesive and adsorbent materials.