Biowaste to bioenergy nexus: Fostering sustainability and circular economy

Existing fossil-based commercial products present a significant threat to the depletion of global natural resources and the conservation of the natural environment. Also, the ongoing generation of waste is giving rise to challenges in waste management. Conventional practices for the management of waste, for instance, incineration and landfilling, emit gases that contribute to global warming. Additionally, the need for energy is escalating rapidly due to the growing populace and industrialization. To address this escalating desire in a sustainable manner, access to clean and renewable sources of energy is imperative for long-term development of mankind. These interrelated challenges can be effectively tackled through the scientific application of biowaste-to-bioenergy technologies. The current article states an overview of the strategies and current status of these technologies, including anaerobic digestion, transesterification, photobiological hydrogen production, and alcoholic fermentation which are utilized to convert diverse biowastes such as agricultural and forest residues, animal waste, and municipal waste into bioenergy forms like bioelectricity, biodiesel, bio alcohol, and biogas. The successful implementation of these technologies requires the collaborative efforts of government, stakeholders, researchers, and scientists to enhance their practicability and widespread adoption.

Transesterification Induced Multifunctional Additives Enable High-Performance Lithium Metal Batteries

The electrolyte chemistry is crucially important for promoting the practical application of lithium metal batteries (LMBs). Here, we demonstrate for the first time that 1,3-dimethylimidazolium dimethyl phosphate (DIDP) and trimethylsilyl trifluoroacetate (TMSF) can undergo in situ transesterification in carbonate electrolyte to generate dimethyl trimethylsilyl phosphate (DTMSP) and 1,3-dimethylimidazolium trifluoroacetate (DITFA) as multifunctional additives for LMBs. H2O and HF can be removed by the Si-O group in DTMSP to improve the moisture resistance of electrolyte and the stability of cathode. Furthermore, the dissolution of lithium nitrate (LiNO3) in carbonate electrolyte can be promoted by the trifluoroacetate anion (TFA-) in DITFA, thereby optimizing the solvation structure and transport kinetics of Li+. More importantly, both DTMSP and DITFA tend to preferential redox decomposition due to the low lowest unoccupied molecular orbital (LUMO) and high highest occupied molecular orbital (HOMO). Consequently, a thin and robust layer rich in P/N/Si on the cathode and an inorganic-rich layer (e.g. Li3N/Li3P) on the anode can be constructed and superior electrochemical performances are achieved. This artificial transesterification strategy to introduce favorable additives paves an efficient and ingenious route to high-performance electrolyte for LMBs.

Synthesis of New Multifunctional Linolenic Acid Vanillyl Ester and Investigation of Antioxidant and Antibacterial Activities

Vanillyl alcohol (VA) possesses potent antioxidant activity, yet its applicability is hindered by its limited solubility in emulsions or non-polar organic solvents. Conversely, long-chain polyunsaturated fatty acids exhibit antibacterial properties. The combination of these compounds offers the prospect of developing novel phenolic lipid compounds with dual antioxidant and antibacterial activities, alongside enhanced solubility capabilities. In this investigation, linolenic acid vanillyl ester (LAVE) was synthesized from VA and linseed oil (LO) through a transesterification reaction employing immobilized lipase. Optimization of LAVE production was achieved by varying reaction temperature, substrate concentration, and reaction time. LAVE demonstrated efficacy in scavenging both 2,2-diphenyl-1-picryhydrazyl and 2,2'-azino-bis (3-ethylbenthiazoline-6-sulphonic acid) radicals in organic solvents. Antioxidant testing via lipid oxidation analysis revealed that LAVE, when distributed within emulsions, effectively impeded the formation of conjugated dienes and conjugated trienes. Furthermore, LAVE exhibited antibacterial activity against four strains of spoilage bacteria: Bacillus subtilis, Bacillus coagulans, Pseudomonas fluorescens, and Alcaligenes faecalis. Zeta potential analysis substantiated the binding of LAVE to the bacterial cell surface. Propidium iodide uptake assay and fluorescence microscopy further elucidated that LAVE induces cell lysis by augmenting membrane permeability.

Biodiesel production and exploring properties of Datura stramonium L. oil with its optimization using combined approaches-Taguchi, grey relational analysis, and response surface methodology

Biodiesel production through the synthesis of Datura stramonium L. oil is studied to explore the most efficient approaches to suggest an alternate feedstock for biodiesel production. The main objective of this work is to optimize the process variables of biodiesel synthesis by using some statistical approach (Taguchi method, grey relational analysis (GRA), and response surface methodology (RSM) analyzing three parameters, i.e., alcohol-to-oil molar ratio, catalyst (NaOH) concentration, and process temperature for achieving maximum biodiesel derived from Datura stramonium L. oil. The transesterification process is applied by using an ultrasonic-assisted technique. Grey relational analysis (GRA) was successfully applied with the Taguchi method resulting in the optimum combination of A2B1C1. Based on the findings, the best operating conditions for transesterifying are attained with the RSM approach consisting of a 5.697:1 molar ratio (level 2), 0.3 (wt.%) NaOH concentration (level 1), and 70 °C process temperature (level 1). With a value of 87.02%, these ideal operating conditions produce the maximum yield as compared to grey relational analysis (GRA) yields 83.99%. The obtained results have been verified through the characterization of oil and biodiesel as well. Also, the fuel qualities of DSL biodiesel were identified and assessed. DSL oil was found 137.6 degrees of unsaturation during fatty acid profile analysis. DSL biodiesel was found the best kinematic viscosity (4.2 mm2/s) and acid value (0.49) when compared to Karanja and palm biodiesel. D. stramonium L. was recognized as a suitable species for biodiesel feedstock according to the findings.

Analyzing the performance of synthesized nano-catalysts for transesterification of waste cooking oil as environment friendly drilling fluid

Ester-based drilling fluids (EBDF) are preferred over oil-based drilling fluids (OBDF) and water-based drilling fluids (WBDF) because of their great biodegradability, low toxicity, and improved performance. In this work, waste cooking oil methyl ester (WCOME) was used to prepare an environmentally friendly EBDF. Through a transesterification process utilizing a modified calcium oxide based heterogenous catalyst, the waste cooking oil is transformed into waste cooking oil methyl ester. Response surface approach was used to strengthen the transesterification. The optimize conditions for CaO/Al2O3 resulted in the highest yield of 96.56% at a molar ratio of 11.9:1, 3.19 wt % of CaO/Al2O3, 53.79 °C, and 76.86 min. In contrast, CaO/TiO2 yielded 98.15% at a molar ratio of 11.99:1, with a CaO/TiO2 of 2.53 wt % at 59.79 in 68.14 min. Additionally, two separate densities of 9 ppg and 12 ppg EBDF are formulated with two distinct oil-to-water ratios (70:30 and 80:20) using synthesized WCOME. To assess the effectiveness of formulated EBDF thorough rheological investigation is conducted at 150°. Additionally, the filtration loss at HPHT conditions, emulsion stability, and Barite sag analysis of the drilling fluid are all analyzed at before ageing and after dynamic ageing. With better rheological features, less fluid loss, good emulsion stability, and minimal barite sagging, the designed EBDF performs efficiently. The drilling fluid met the API requirement and demonstrated stability even after ageing at 250 °F for 72 h, suggesting that it may be used for extended periods of time in drilling.

Performance testing of moringa oleifera seed oil biodiesel with additives in diesel engine

Now a day's liquid biodiesel fuels utilization that are produced from renewable natural resources such as moringa oleifera seeds using transesterification method accounts among the best alternative option for substituting conventional fossil fuels. This investigation shows production of biodiesel from moringa oleifera seeds by transesterification process with an additive of diethyl ether (DEE2%). It also finds out the efficiency and emission analysis of three fuels namely pure diesel, B20 (20% moringa blended with 80% diesel), and B20DEE2% (20% Moringa &2%DEE additive blended with 78% diesel) compression ignition engine using single cylinder, 4-stroke direct injection method. The observations of the fuel characterization show that B20 and B20DEE2% biodiesel blended fuels have nearly equal characteristics such as viscosity, density, and calorific values that compared to diesel fuel. Moreover, these fuels have comparable performance such as brake thermal efficiency, brake power, brake torque, and specific fuel consumption compared to clear diesel fuel, and especially B20DEE2% have better emission condition than B20 biodiesel blend fuel.

General Construction of Asymmetric Amine Ethers via Efficient Transesterification

A novel method to prepare asymmetric amine ethers is reported. Tertiary amine alcohol hydrogen sulfate intermediates are prepared through a reactive distillation process, followed by the transesterification process to afford eventually asymmetric amine ethers. Experiments and DFT calculations revealed the essential roles the sulfate group plays in the highly selective monoesterification process. This clean method is tolerant towards various functional groups with good yields under mild condition, which is obviously superior compared to the conventional processes.

Application of Response Surface Methodology (RSM) in the statistical evaluation of biodiesel production from the neutral lipids of the Coelastrella-Nannochloropsis consortium

The paramount challenge in economically workable microalgal biodiesel production is the selection of a competent catalyst to improve the fatty acid methyl ester yield with desirable fatty acid composition. Though countless researchers have explored different homogeneous and heterogeneous catalysts to improve the transesterification efficacy, achieving greater biodiesel production from the neutral lipids of the microalgal consortium using a statistical tool, response surface methodology is scarce. Thus, the present study applied Response surface methodology to statistically analyze the biodiesel production from the neutral lipids of the indigenous Coelastrella-Nannochloropsis consortium (CNC) on the way to commercial feasibility. Onset of the study, the neutral lipids and acid value of the CNC were determined to be 18.74% and 2.73%, respectively. The transesterification of the neutral lipids of CNC was optimized through the coded factors in the RSM for various reaction parameters as combined influence viz., (i) Catalyst dose: methanol volume, (ii) Catalyst dose: reaction time; (iii) Catalyst dose: reaction temperature, (iv) Time: temperature, (v) time: methanol volume, (vi) temperature: methanol volume. Based on the ANOVA, coefficient determination, 2% KOH, 2 h time, 70 °C temperature, and 9 mL methanol volume were ascertained to be optimal values to accomplish 92% biodiesel production. Further, the biodiesel has desirable palmitic, palmitoleic, stearic, oleic, linoleic, and linolenic acids, with palmitic acid as the prevalent fatty acid contributing 16-18%. In addition, the tested fuel properties of CNC biodiesel satisfy international biodiesel standards.

Transesterification with CE15 glucuronoyl esterase from Cerrena unicolor reveals substrate preferences

PURPOSE

Glucuronoyl esterases (GE, family CE15) catalyse the cleavage of ester linkages in lignin-carbohydrate complexes (LCCs), and this study demonstrate how transesterification reactions with a fungal GE from Cerrena unicolor (CuGE) can reveal the enzyme's preference for the alcohol-part of the ester-bond.

METHODS

This alcohol-preference relates to where the ester-LCCs are located on the lignin molecule, and has consequences for how the enzymes potentially interact with lignin. It is unknown exactly what the enzymes prefer; either the α-benzyl or the γ-benzyl position. By providing the enzyme with a donor substrate (the methyl ester of either glucuronate or 4-O-methyl-glucuronate) and either one of two acceptor molecules (benzyl alcohol or 3-phenyl-1-propanol) we demonstrate that the enzyme can perform transesterification and it serves as a method for assessing the enzyme's alcohol preferences.

CONCLUSION

CuGE preferentially forms the γ-ester from the methyl ester of 4-O-methyl-glucuronate and 3-phenyl-1-propanol and the enzyme's substrate preferences are primarily dictated by the presence of the 4-O-methylation on the glucuronoyl donor, and secondly on the type of alcohol.

Recent advances in transesterification for sustainable biodiesel production, challenges, and prospects: a comprehensive review

Biodiesel, a renewable and sustainable alternative to fossil fuels, has garnered significant attention as a potential solution to the growing energy crisis and environmental concerns. The review commences with a thorough examination of feedstock selection and preparation, emphasizing the critical role of feedstock quality in ensuring optimal biodiesel production efficiency and quality. Next, it delves into the advancements in biodiesel applications, highlighting its versatility and potential to reduce greenhouse gas emissions and dependence on fossil fuels. The heart of the review focuses on transesterification, the key process in biodiesel production. It provides an in-depth analysis of various catalysts, including homogeneous, heterogeneous, enzyme-based, and nanomaterial catalysts, exploring their distinct characteristics and behavior during transesterification. The review also sheds light on the transesterification reaction mechanism and kinetics, emphasizing the importance of kinetic modeling in process optimization. Recent developments in biodiesel production, including feedstock selection, process optimization, and sustainability, are discussed, along with the challenges related to engine performance, emissions, and compatibility that hinder wider biodiesel adoption. The review concludes by emphasizing the need for ongoing research, development, and collaboration among academia, industry, and policymakers to address the challenges and pursue further research in biodiesel production. It outlines specific recommendations for future research, paving the way for the widespread adoption of biodiesel as a renewable energy source and fostering a cleaner and more sustainable future.

Highly effective synthesis of novel structured phospholipid emulsifiers using magnetically recyclable Fe3O4@SiO2/M (M = Zn or Al) composite

It is of great importance to develop a most efficient, recyclable, and ecofriendly process to produce novel structured phospholipid emulsifiers. Herein, innovative medium-chain structured phospholipid (MCSPL) emulsifiers were synthesized through transesterification of soybean lecithins with medium-chain fatty acids (MCFAs) promoted by Zn- or Al-incorporated Fe3O4@SiO2, denoted by Fe3O4@SiO2/M (M = Zn or Al). Resultingly, Fe3O4@SiO2/M (M = Zn or Al) exhibited the most superior reactivity with 97.1% or 88.7% MCFA incorporation to other benchmark catalysts and also had excellent magnetic separability and recyclability. Noticeably, targeted MCSPLs possessed almost more superior emulsifying properties to other phospholipid emulsifiers, and had potential for use as oil-in-water emulsifiers. Conclusively, the present findings demonstrate that transesterification promoted by Fe3O4@SiO2/M (M = Zn or Al) can be a promising approach for green, economic, and highly effective synthesis of novel dual-function phospholipid emulsifiers with bioactive and emulsifying properties in food, pharmaceutical, and cosmetic industries.

Green biosynthesis of DHA-phospholipids in tailor-made supersaturated DHA aqueous solution and catalytic mechanism study

Docosahexaenoic acid-phospholipids (DHA-PLs) were prepared via lipase-mediated transesterification of DHA donor and phosphatidylcholine (PC) in a purely aqueous solution. Pre-existing carriers would play the role as "artificial interfaces" to adsorb water-insoluble PC and made them disperse in water. DHA donors were concentrated by a pH-responsive method and presented as supersaturated salt solutions. 153 triacylglycerol lipase structures were analyzed and screened in silico. Transesterification was carried out to further evaluate the six lipase candidates. Lipase B from Candida antarctica (CALB) was the best biocatalyst with 34.8% of DHA incorporation and 80.0% of PLs yields (involving 38.1% PC and 41.9% sn-1 lyso-PC). Toxic organic solvents were avoided. Six possible microunits of our aqueous system consisting of three PLs donors (PC, lyso-PC, sn-glycero-3-PC) and two DHA donors (DHA and DHA salts), were simulated by molecular dynamics (MD) to illustrate the enzymatic mechanism based on diffusional channels, competitive bindings, and enzymatic structures.

Plastic bio-mitigation by Pseudomonas mendocina ABF786 and simultaneous conversion of its CO2 byproduct to microalgal biodiesel

Bio-mitigation of plastics by microorganisms generates carbon dioxide (CO2) that can be utilized for algal biomass generation. Pseudomonas mendocina ABF786, reportedly the most efficient plastic-degrading bacteria, was screened using the modified most probable number technique. This study highlights the use of an integrative prototype for the production of microalgal biomass (Chlorella vulgaris) in combination with bio-mitigation of plastics, which serves a dual purpose: (i) increased plastic-degradation capability by microorganisms (53%-85% increase in plastic weight loss) due to removal of CO2 feedback inhibition and (ii) increased algal biomass generation (200%-237%) due to supply of extra CO2 from plastic degradation to the algal cultivation flask. Whole-genome sequencing and functional annotation confirmed that all the genes involved in the mineralization of plastic to CO2 are present within the genome of P. mendocina ABF786. Using two or more microbial cultures for remediation may increase the process efficiency.

Synthesis, catalysts and enhancement technologies of biodiesel from oil feedstock - A review

Biodiesel is considered as one of the most promising alternative fuels due to the depletion of fossil fuels and the need to cope with potential energy shortages in the future. This article provides a thorough analysis of biodiesel synthesis, covering a variety of topics including oil feedstock, synthesis methods, catalysts, and enhancement technologies. Different oil feedstock for the synthesis of biodiesel is compared in the review, including edible plant oil, non-edible plant oil, waste cooking oil, animal fat, microbial oil, and algae oil. In addition, different methods for the synthesis of biodiesel are discussed, including direct use, blending, thermal cracking, microemulsions, and transesterification processes, highlighting their respective advantages and disadvantages. Among them, the transesterification method is the most commonly used and a thorough examination is given of the benefits and drawbacks of utilizing enzymatic, heterogeneous, and homogeneous catalysts in this process. Moreover, this article provides an overview of emerging intensification technologies, such as ultrasonic and microwave-assisted, electrolysis, reactive distillation, and microreactors. The benefits and limitations of these emerging technologies are also reviewed. The contribution of this article is offering a thorough and detailed review of biodiesel production technologies, focusing mainly on recent advances in enhanced chemical reaction processes. This provides a resource for researchers to assess and compare the latest advancements in their investigations. It also opens up the potential for enhancing the value of oil feedstocks efficiently, contributing to the development of new energy sources.

On-Demand Activation of Transesterification by Chemical Amplification in Dynamic Thiol-Ene Photopolymers

Chemical amplification is a well-established concept in photoresist technology, wherein one photochemical event leads to a cascade of follow-up reactions that facilitate a controlled change in the solubility of a polymer. Herein, we transfer this concept to dynamic polymer networks to liberate both catalyst and functional groups required for bond exchange reactions under UV irradiation. For this, we exploit a photochemically generated acid to catalyse a deprotection reaction of an acid-labile tert-butoxycarbonyl group, which is employed to mask the hydroxy groups of a vinyl monomer. At the same time, the released acid serves as a catalyst for thermo-activated transesterifications between the deprotected hydroxy and ester moieties. Introduced in an orthogonally cured (450 nm) thiol-click photopolymer, this approach allows for a spatio-temporally controlled activation of bond exchange reactions, which is crucial in light of the creep resistance versus reflow ability trade-off of dynamic polymer networks.

Highly Efficient Depolymerization of Waste Polyesters Enabled by Transesterification/Hydrogenation Relay Under Mild Conditions

The efficient depolymerization of polyesters under mild conditions remains a significant challenge. Herein, we demonstrate a highly efficient strategy for the degradation of a diverse array of waste polyesters as low to 80 °C, 1 bar H2 . The key to the success of this transformation relied on the initial transesterification of macromolecular polyester into more degradable oligomeric fragments in the presence of CH3 OH and the subsequent hydrogenation by the use of the rationally designed quinaldine-based Ru complex. Controlled experiments and preliminary mechanistic studies disclosed the quinaldine-based catalysts could be hydrogenated to the eventually active species, which has been confirmed by X-ray diffraction analysis and directly used as a catalyst in the hydrogenolysis of polyester. The strong viability and high activity of this new species in protic solvent were explained in detail. Besides, the crucial role of CH3 OH in promoting reaction efficiency during the whole process was also elucidated. The synthetic utility of this method was further illustrated by preparing 1,4-cyclohexanedimethanol (CHDM) from waste polyethylene terephthalate (PET).

Does the Varying Reactivity in the Transient Polymer Network through Dynamic Exchange Regulate the Closed-Loop Circularity in Polyolefin Vitrimers?

According to current projections, of the 400 mega tons of plastic produced globally, 70% is waste and of that only 16% is recycled and the rest is incinerated. This is estimated to contribute to ca. 16% of the net carbon emission by 2050. Such a massive amount of unmanaged plastic waste and the associated huge carbon footprint sets a significant challenge to tackle in the coming decades. To achieve net-zero carbon emission, closed-loop circular economy in plastics is crucial but collection, sorting and processing the postconsumer recycled (PCR) plastics poses humongous challenge in achieving this circularity, unless an effective strategy is designed. In a first of its kind, a designer biobased molecule was synthesized (here maleated castor oil, mCO) that is steric and thermally stable and forms in situ "homo-cross-linking" in the melt post grafting onto PCR-PP. This designer molecule, besides offering a transient network, helps bridge the fragmented PP chains which is usually not amenable from the traditional grafting (like maleic anhydride), thereby addressing a long-standing challenge of retaining the properties post grafting due to chain scission in the melt. The resulting maleated (m) PCR-PP now offers abundant functionality which helped us design single and dual covalent adaptable network (CANs) and evaluate their consequences on the structure-property correlation. The PCR-PP Vitrimers demonstrate a distinct rubbery plateau in the melt and reprocessability with >90% recovery in mechanical properties even after the fifth sequence of recycling. We propose here for the first time how the varying reactivity (single or dual) in the transient polymer network, through dynamic exchange, regulates the closed-loop circularity in PP Vitrimers. Our results begin to suggest that the varying reactivity should be taken into account as an additional design parameter, as it influences both the stress relaxation rates and the flow activation energy. We now understand that the topology reconfiguration is strongly dependent on this varying reactivity, which also controls the overall crystalline morphology and the structural properties in the Vitrimers. This study, in addition to opening new avenues for recycling PP, will help guide researchers working in this field from both academia and industry.

Biocatalytic production of biolubricants: Strategies, problems and future trends

The increasing worries by the inadequate use of energy and the preservation of nature are promoting an increasing interest in the production of biolubricants. After discussing the necessity of producing biolubricants, this review focuses on the production of these interesting molecules through the use of lipases, discussing the different possibilities (esterification of free fatty acids, hydroesterification or transesterification of oils and fats, transesterification of biodiesel with more adequate alcohols, estolides production, modification of fatty acids). The utilization of discarded substrates has special interest due to the double positive ecological impact (e.g., oil distillated, overused oils). Pros and cons of all these possibilities, together with general considerations to optimize the different processes will be outlined. Some possibilities to overcome some of the problems detected in the production of these interesting compounds will be also discussed.

Non-activated Esters as Reactive Handles in Direct Post-Polymerization Modification

Non-activated esters are prominently featured functional groups in polymer science, as ester functional monomers display great structural diversity and excellent compatibility with a wide range of polymerization mechanisms. Yet, their direct use as a reactive handle in post-polymerization modification has been typically avoided due to their low reactivity, which impairs the quantitative conversion typically desired in post-polymerization modification reactions. While activated ester approaches are a well-established alternative, the modification of non-activated esters remains a synthetic and economically valuable opportunity. In this review, we discuss past and recent efforts in the utilization of non-activated ester groups as a reactive handle to facilitate transesterification and aminolysis/amidation reactions, and the potential of the developed methodologies in the context of macromolecular engineering.

Enzymatic synthesis of novel pyrrole esters and their thermal stability

In the present work a simple enzymatic approach (Novozym 435) for transesterification to synthesize pyrrole esters was reported. To generate the best reaction conditions, which resulted in the optimum yield of 92%, the effects of lipase type, solvent, lipase load, molecular sieves, substrate molar ratio of esters to alcohol, reaction temperature, reaction duration, and speed of agitation were evaluated. The range of alcohols was assessed under optimal circumstances. The spectrum observations conclusively demonstrated that the compounds could be generated with high yield under the circumstances utilized for synthesis. The odor characteristics of the pyrrolyl esters obtained were examined by gas chromatography-mass spectrometry-olfactometry (GC-MS-O). Among them, compounds of benzhydryl 1H-pyrrole-2-carboxylate (3j), butyl 1H-pyrrole-2-carboxylate (3k) and pentyl 1H-pyrrole-2-carboxylate (3l) present sweet and acid aroma. In addition, the thermal degradation process was further studied using the Py-GC/MS (pyrolysis-gas chromatography/mass spectrometry), TG (thermogravimetry), and DSC (differential scanning calorimeter) techniques. The outcomes of the Py-GC/MS, TG, and DSC techniques show that they have excellent thermal stability.

Rhizopus stolonifer biomass catalytic transesterification capability: optimization of cultivation conditions

BACKGROUND

Using fungal biomass for biocatalysis is a potential solution for the expensive cost of the use o enzymes. Production of fungal biomass with effective activity requires optimizing the cultivation conditions.

RESULTS

Rhizopus stolonifer biomass was optimized for transesterification and hydrolysis of waste frying oil (WFO). Growth and biomass lipolytic activities of R. stolonifer improved under shaking conditions compared to static conditions, and 200 rpm was optimum. As biomass lipase and transesterification activities inducer, olive oil was superior to soybean, rapeseed, and waste frying oils. Biomass produced in culture media containing fishmeal as an N-source feedstock had higher lipolytic capabilities than corn-steep liquor and urea. Plackett Burman screening of 9 factors showed that pH (5-9), fishmeal (0.25-1.7%, w/v), and KH2PO4 (0.1-0.9%, w/v) were significant factors with the highest main effect estimates 11.46, 10.42, 14.90, respectively. These factors were selected for response surface methodology (RSM) optimization using central composite design (CCD). CCD models for growth, biomass lipase activity, and transesterification capability were significant. The optimum conditions for growth and lipid modification catalytic activities were pH 7.4, fishmeal (2.62%, w/v), and KH2PO4 (2.99%, w/v).

CONCLUSION

Optimized culture conditions improved the whole cell transesterification capability of Rhizopus stolonifer biomass in terms of fatty acid methyl ester (FAME) concentration by 67.65% to a final FAME concentration of 85.5%, w/w.

Obtention of fatty acids and phenolic compounds from Colombian cashew (Anacardium occidentale) nut shells using pyrolysis: towards a sustainable biodiesel production

Sustainable management of non-edible agricultural residues of cashew nut production is a concern in Colombia. Therefore, this study aimed to study the fatty acid content of a pyrolytic liquid obtained from cashew nut shells (CNSs) from the Vichada region in Colombia. Transesterification of pyrolytic liquid was conducted to obtain biodiesel at the micro-scale as the first approach for this valorization route. Proximal analysis of samples was carried out using advanced analytical techniques (UHPLC-MS and CG-MS) whereas phenolic content and antioxidant activity were determined. The production yield of pyrolytic liquid was 69.15 ± 5.07% weight (wt.), at 550 °C and 2h of pyrolysis and the liquid was rich in fatty acids (∼70% wt.) and long-chain phenols (∼18% wt.). Among the phenolic compounds in liquid, mainly unsaturated C15:4 cardanol was identified (82.1 ± 5.5 mg/g), whereas the antioxidant activity of pyrolytic liquid was 0.714 ± 0.030 TE/g. Moreover, the biodiesel yield was 81% using catalyst sodium methoxide (12% v), and 50 °C and 26 min for the reaction. The obtained biodiesel in the hexane fraction was rich in methyl trans-8-octadecanoate (20.9 % wt.) and methyl palmitate (14.3 % wt.), being the representative compounds in the biodiesel. Therefore, the results indicated that thermal conversion of CNSs for obtaining biodiesel on a one-step process is a suitable strategy for the management of toxic and non-edible cashew residues. Finally, this is the first work of its kind that propose in detail the composition of pyrolytic liquid obtained from Colombian cashew nut residues under the proximate analysis approach and using advanced analytical techniques.

Utilizing an ultra-sonication process to optimize a two-step biodiesel production from Karanja oil

Currently, biodiesel is produced from non-edible oils, which have various poisonous and un-saponifiable components; therefore, it is harmful and unfit for humans. Biodiesel replaces petro-diesel fuel, which can be used as additives or substitutes for diesel engines. The novelty of the present study is to optimize the process parameters of a two-step (esterification and transesterification) process for biodiesel production using high free fatty acid (FFA) containing Karanja oil (Pongamia pinnata oil), with the ultrasound (US) process intensification (PI) technique, which is carried out for the first time. In the first step, a reduction in the initial FFA concentration of 11.06% was achieved through optimization of the esterification process using response surface methodology (RSM)-supported central composite design (CCD) method in which methanol:oil molar ratio of 6:1 and 60 °C reaction temperature kept as fixed parameter, whereas H₂SO₄ catalyst loading (0.5-1.5 w/w%) and reaction time (15-45 min.) were varied. The FFA value is reduced to 1.56% under the optimal condition (32.8 min reaction time and 1.14 w/w% of catalyst loading). The second step of optimization of the transesterification of esterified oil was performed by applying RSM supported Box-Behnken design (BBD) method with varying independent parameter ranges such as the molar ratio (A), CH₃OK catalyst loading (B), and reaction time (C) with the range of 6:1-9:1 (methanol: oil), 0.5-1.5 w/w%, and 10-30 min., respectively. A biodiesel yield of 98.16% was obtained under optimal conditions of a molar ratio of 7.6:1, catalyst loading of 0.98 w/w%, a reaction time of 20.6 min., and a reaction temperature of 60 °C (constant). Superior optimization results were observed than the conventional stirring method. The biodiesel's estimated characteristics were discovered to be within ASTM criteria and suitable for blending with diesel fuel.

Biocatalysis of triglycerides transesterification using fungal biomass: a biorefinery approach

BACKGROUND

The use of microbial biomasses, such as fungal biomass, to catalyze the transesterification of triglycerides (TG) for biodiesel production provides a sustainable, economical alternative while still having the main advantages of expensive immobilized enzymes.

RESULTS

Biomasses of Aspergillus flavus and Rhizopus stolonifera were used to catalyze the transesterification of TG in waste frying oil (WFO). Isopropanol as an acyl-acceptor reduced the catalytic capability of the biomasses, while methanol was the most potent acyl-acceptor with a final fatty acid methyl ester (FAME) concentration of 85.5 and 89.7%, w/w, for R. stolonifer and A. flavus, respectively. Different mixtures of the fungal biomasses were tested, and higher proportions of A. flavus biomass improved the mixture's catalytic capability. C. sorokiniana cultivated in synthetic wastewater was used as feedstock to cultivate A. flavus. The biomass produced had the same catalytic capability as the biomass produced in the control culture medium. Response surface methodology (RSM) was adopted using central composite design (CCD) to optimize the A. flavus biomass catalytic transesterification reaction, where temperature, methanol concentration, and biomass concentration were selected for optimization. The significance of the model was verified, and the suggested optimum reaction conditions were 25.5 °C, 250 RPM agitation with 14%, w/w, biomass, 3 mol/L methanol, and a reaction duration of 24 h. The suggested optimum conditions were tested to validate the model and a final FAME concentration of 95.53%. w/w was detected.

CONCLUSION

Biomasses cocktails might be a legitimate possibility to provide a cheaper technical solution for industrial applications than immobilized enzymes. The use of fungal biomass cultivated on the microalgae recovered from wastewater treatment for the catalysis of transesterification reaction provides an additional piece of the puzzle of biorefinery. Optimizing the transesterification reaction led to a valid prediction model with a final FAME concentration of 95.53%, w/w.

Transesterification of phosphatidylcholine with DHA-rich algal oil using immobilized Candida antarctica lipase B to produce DHA-phosphatidylcholine

Docosahexaenoic acid (DHA) enriched with phospholipids (PLs) (DHA-PLs) is a type of structured PL with good physicochemical and nutritional properties. Compared to PLs and DHA, DHA-PLs has higher bioavailability and structural stability and many nutritional benefits. To improve the enzymatic synthesis of DHA-PLs, this study investigated the preparation of phosphatidylcholine (PC) enriched with DHA (DHA-PC) via enzymatic transesterification of algal oil, which is rich in DHA-triglycerides, using immobilized Candida antarctica lipase B (CALB). The optimized reaction system incorporated 31.2% DHA into the acyl chain of PC and converted 43.6% PC to DHA-PC within 72 h at 50 °C, 1:8 PC: algal oil mass ratio, 25% enzyme load (based on total substrate mass), and 0.02 g/mL molecular sieve concentration. Consequently, the side reactions of PC hydrolysis were effectively suppressed and products with high PC content (74.8%) were produced. Molecular structure analysis showed that exogenous DHA was specifically incorporated into the sn-1 site of the PC by immobilized CALB. Furthermore, the evaluation of reusability with eight cycles showed that the immobilized CALB had good operational stability in the present reaction system. Collectively, this study demonstrated the applicability of immobilized CALB as a biocatalyst for synthesizing DHA-PC and provided an improved enzyme-catalyzed method for future DHA-PL synthesis.

Immobilization of Subtilisin Carlsberg and its use for transesterification of N-acetyl-L-phenylalanine ethyl ester in organic medium

In this study, inorganic-based carrier perlite (PER) and cyclodextrin-modified perlite (PER-CD) were used for Subtilisin Carlsberg (SC) immobilization. For enzyme immobilization, the supports aminated with 3-aminotriethoxysilane were first activated with glutaraldehyde (GA) and genipin (GE), and then, the immobilized enzymes (PER-SC and PER-CD-SC) were obtained. The reaction medium for SC immobilization consisted of 500 mg carrier and 5 ml (1 mg/ml) enzyme solution. The immobilization conditions were pH 8.0, 25 °C, and 2 h incubation time. Free and immobilized SC were used for transesterification of N-acetyl-L-phenylalanine ethyl ester (APEE) with 1-propanol in tetrahydrofuran (THF). The transesterification activity of the enzyme and the yield of the transesterification reaction were determined by gas chromatography (GC). 50 mg of immobilized or 2.5 mg of free SC was added to the reaction medium, which was prepared as 1 mmol APEE and 10 mmol alcohol in 10 mL of THF. The conditions for the transesterification reaction were 60 °C and 24 h of incubation. The structure and surface morphology of the prepared carriers were characterized using scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). Casein substrate was used in the optimization study. The optimum temperature and pH for SC activity were found to be 50 °C and pH 8.0, respectively, for free and immobilized SC. The thermal stability of immobilized SC was found to be greater than that of free SC. At the end of 4 h of exposure to high temperature, the immobilized enzyme maintained its activity at approximately 50%, while the free enzyme was maintained at approximately 20%. However, modification with cyclodextrin did not alter the thermal stability. The transesterification yield was found to be approximately 55% for the free enzyme, while it was found to be approximately 68% and 77% for PER-SC and PER-CD-SC, respectively. The effect of metal ions and salts on transesterification yield was examined. The results showed that the addition of metal ions decreased the percentage of transesterification by approximately 10% compared to the control group, whereas the addition of salt significantly decreased the percentage of transesterification by 60-80% compared to the control group.

Preparation and characterization of biodiesel from waste cooking oils using heterogeneous Catalyst(Cat.TS-7) based on natural zeolite

Biodiesel is known as renewable biodegradable and less polluting material. It is produced by transesterification of triglycerides found in vegetable oil or animal fats. Many studies have been conducted on biodiesel production using homogeneous catalysts, but they are very expensive and not environmentally friendly. On the other hand, heterogeneous catalysts are cost-effective from the production process and ecofriendly. In this study, zeolite ore was used as a solid heterogeneous catalyst for the production of biodiesel by the transesterification reaction of waste cooking oils and studying the possibility of reusing it for several cycles under optimal reaction conditions. The catalyst was characterized by different techniques, such as TG-DTA, FTIR, XRD and TPD methods. High-quality biodiesel with 93% yield was obtained under optimal reaction conditions with the ratio of oil to methanol (1:9) mol, amount of catalyst (1.5% by weight of oil), at temperature (60 ^°C), and reaction time of 2 h. Biodiesel has been characterized using infrared spectroscopy, GC/MS, its physical and chemical specifications have been studied and compared with the American (ASTM) and European (EN) standards.

Optimization of performance characteristics in diesel engine utilizing Chlorella vulgaris fuel-a green approach towards sustainable development

Sustainable renewable energy fuel is used to reduce fossil fuel consumption and mitigate global warming pollution. The effect of diesel and biodiesel blends on engine combustion, performance, and emissions were studied at various engine loads, compression ratios, and engine speed. Chlorella vulgaris biodiesel is derived through a transesterification process and diesel and biodiesel blends are prepared at 20% incremental volume up to CVB₁₀₀. The performance such as brake thermal efficiency reduced by 1.49%, specific fuel consumption increased by 2.78%, and exhaust gas temperature increased by 0.43% for CVB₂₀ as compared to diesel. Similarly, emissions were reduced such as smoke, particulate matters. CVB₂₀ shows close performance and lower emission than diesel at a 15.5 compression ratio and 1500 rpm engine speed. The increasing compression ratio has a positive impact on engine performance and emission except for NOx. Similarly, increasing engine speed has a positive impact on engine performance and emission except for exhaust gas temperature. The performance of a diesel engine fueled with a blend of diesel and Chlorella vulgaris biodiesel is optimized by varying compression ratio, engine speed, load, and blend. It was found that at 8 compression ratio, 1835 rpm speed, 88% engine load, and 20% biodiesel blend the maximum BTE obtained 34% while minimum SFC 0.158 kg/kWh is obtained employing research surface methodology tool.

Transesterification of RNA model induced by novel dinuclear copper (II) complexes with bis-tridentate imidazole derivatives

Two novel bis-tridentate imidazole derivatives were conveniently synthesized using a 'one-pot' method. Their dinuclear (Cu₂L¹Cl₄, Cu₂L²Cl₄) and mononuclear (CuL¹Cl₂, CuL²Cl₂∙H₂O) copper (II) complexes were synthesized to comparably evaluate their reactivities in the hydrolytic cleavage of 2-hydroxypropyl p-nitrophenyl phosphate (HPNP) as a classic RNA model. Single crystals of Cu₂L¹Cl₄ and Cu₂L²Cl₄ indicate that both of them are centrosymmetric, and each central copper ion is penta-coordinated. Regarding the transesterification of HPNP, both of dinuclear ones exhibited excess one order of magnitude rate enhancement in contrast with auto-hydrolysis reaction. Under comparable conditions, dinuclear complexes displayed no more than twofold increase in activity over their mononuclear analogues, which verifies the lack of binuclear cooperation effect due to long Cu-to-Cu space.

Preparation and characterization of diacylglycerol via ultrasound-assisted enzyme-catalyzed transesterification of lard with glycerol monolaurate

The study aimed to evaluate the effect of ultrasonic pretreatment on the transesterification of lard with glycerol monolaurate (GML) using Lipozyme TL IM to synthesize diacylglycerol (DAG), and the physicochemical properties of lard, GML, ultrasonic-treated diacylglycerol (named U-DAG), purified ultrasonic-treated diacylglycerol obtained by molecular distillation (named P-U-DAG), and without ultrasonic-treated diacylglycerol (named N-U-DAG) were analyzed. The optimized ultrasonic pretreatment conditions were: lard to GML mole ratio 3:1, enzyme dosage 6 %, ultrasonic temperature 80 °C, time 9 min, power 315 W. After ultrasonic pretreatment, the mixtures reacted for 4 h in a water bath at 60 °C, the content of DAG reached 40.59 %. No significant variations were observed between U-DAG and N-U-DAG in fatty acids compositions and iodine value, while P-U-DAG had lower unsaturated fatty acids than U-DAG. Differential scanning calorimetry analysis showed that the melting and crystallization properties of DAGs prepared by ultrasonic pretreatment significantly differed from lard. FTIR spectra noted transesterification reaction from lard and GML with and without ultrasonic pretreatment would not change the structure of lard. However, thermogravimetric analysis proved that N-U-DAG, U-DAG, and P-U-DAG had lower oxidation stability than lard. The higher the content of DAG, the faster the oxidation speed.

Synthesis and characterization of magnetic bifunctional nano-catalyst for the production of biodiesel from Madhuca indica oil

The reusable magnetic multimetal nano-catalyst (Fe₃O₄.Cs₂O) was synthesized using co-precipitation and incipient wetness impregnation methods. It was used to esterify and transesterify Madhuca indica (M. indica) oil to produce biodiesel with methanol. The prepared catalyst, caesium oxide doped on the nano-magnetite core, was characterized using field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). Further, the activity of the catalyst was investigated by subjecting it to a biodiesel reaction. To maximize biodiesel conversion, studies were carried out by varying the process variables like catalyst concentration, methanol-to-oil molar ratio, reaction temperature, and reaction time. A maximum conversion of 97.4% was obtained at the holding conditions of 18:1 methanol-to-oil ratio, 7 wt% catalyst loading, 65 °C reaction temperature, and 300 min reaction time. Moreover, the catalyst recyclability study showed that it could be recycled up to 12 cycles with a conversion of 90% and above. The biodiesel's fuel properties were analysed and found to be within the limits of ASTM D6751 standard.

Ultra-small magnetic Candida antarctica lipase B nanoreactors for enzyme synthesis of bixin-maltitol ester

Bixin has desirable bioactivities but poor water solubility, which limits its practical applications. Enzymatic transesterification of methyl to alditol groups in bixin by Candida antarctica lipase B (CALB) improves bixin water solubility. Herein, magnetic CALB nanoreactors with diameter of 11.7 nm and CALB layer thickness of 3.5 nm were developed by covalently linking CALB onto silicon covered Fe₃O₄ nanoparticles. The CALB loading capacity in nanoreactors achieved 30%. The Michaelis constant (Km) and maximum reaction rate of magnetic CALB nanoreactors were 56.1 mmol/L and 0.2 mmol/(L·min). Magnetic CALB nanoreactors could circularly catalyze bixin-maltitol ester synthesis and keep catalytic efficiency of 62.6% after eight repetitive enzymatic reactions. Additionally, the optimal bixin-maltitol ester synthesis procedure was heating bixin-maltitol mixture at molar ratio of 1:7 in anhydrous 2-methyl-2-butanol-dimethylsulfoxide (8:2, v/v) at 50 °C for 24 h. Bixin-maltitol ester showed improved water solubility at pH 5.5 and 7.0.

Valorization of hazardous waste cooking oil for the production of eco-friendly biodiesel using a low-cost bifunctional catalyst

Biodiesel is considered the prospective substitute for non-renewable fossil fuel-derived sources of energy. However, the high costs of feedstocks and catalysts inhibit its large-scale industrial implementation. From this perspective, the utilization of waste as the source for both catalyst synthesis and feedstock for biodiesel is a rare attempt. Waste rice husk was explored as a precursor to prepare rice husk char (RHC). Sulfonated RHC was employed as a bifunctional catalyst for the simultaneous esterification and transesterification of highly acidic waste cooking oil (WCO) to produce biodiesel. The sulfonation process coupled with ultrasonic irradiation proved to be an efficient technique to induce high acid density in the sulfonated catalyst. The prepared catalyst possessed a sulfonic density and total acid density of 4.18 and 7.58 mmol/g, respectively, and a surface area of 144 m²/g. A parametric optimization was conducted for the conversion of WCO into biodiesel using the response surface methodology. An optimal biodiesel yield of 96% was obtained under the conditions of methanol to oil ratio (13:1), reaction time (50 min), catalyst loading (3.5 wt%), and ultrasonic amplitude (56%). The prepared catalyst showed higher stability up to five cycles with biodiesel yield greater than 80%.

Recent advances and challenges in the utilization of nanomaterials in transesterification for biodiesel production

Due to diminishing fossil fuel supplies and rising energy needs, there has been an ever-increasing demand for renewable energy sources. The available renewable energy resources, such as solar, wind, hydropower, and biofuels, provide a new way of supplying the world's energy needs. Biofuels stand out among them because they are sustainable and have the potential to bring the idea of a global bioeconomy to life. As a result of their production of biofuels like biomethane, biohydrogen, and biodiesel, atmospheric CO₂ is being fixed, eventually lowering the world's carbon footprint. Current developments in the production of bioenergy have concentrated on producing biodiesel among other biofuels. Biodiesel is being produced from a variety of feedstocks using a number of processes, including transesterification, micro-emulsion, direct mixing, and pyrolysis. The most popular method among these is transesterification, which makes use of a variety of catalysts. As a result of the development of nanotechnology, nanocatalysts with desirable properties, such as increased catalytic activity, increased surface area, and superior thermal stability, have been made and modified. In this review, various nanocatalyst types and manufacturing processes are examined in relation to transesterification. It explores how crucial nanocatalysts are in boosting biodiesel production, highlights potential barriers, and makes recommendations for their widespread use in the future.

Synthesis and characterization of barium doped CaO heterogeneous nanocatalyst for the production of biodiesel from Catharanthus roseus seeds: Kinetics, optimization and performance evaluation

The exploitation of petroleum derivatives to meet the energy demands of the cutting edge is thought of as impractical because of asset shortage. The current necessitates that the world community improves future energy sources by developing sustainable, ecofriendly alternatives. In this work, biodiesel is produced through the transesterification of Catharanthus roseus seed oil with a barium-doped CaO heterogeneous nanocatalyst. The catalyst characterization is assessed using FTIR, GC-FID, EDAX, XRD, and SEM. The optimum conditions of time (70 min), temperature (58 °C), the molar ratio of methanol: oil is 15:1, and catalyst load (4% w/w) resulted in a conversion of the maximum biodiesel yield of 91.83%. Finally, by using Catharanthus roseus as a feedstock, the low optimal reaction conditions contribute to the development of the economic impact of biodiesel synthesis. Biodiesel blend (B20) containing barium-doped CaO nanoparticles showed better combustion engine performance and lower emissions than fossil fuels.

A Transformable and Bulky Methacrylate Monomer That Enables the Synthesis of an MMA-nBA Alternating Copolymer: Sequence-Dependent Self-Healing Properties

In this study, we designed a methacrylate molecule with an alkyl-substituted trichloro salicylic acid pendant as a transformable bulky monomer to enable the synthesis of an alternating copolymer of methyl methacrylate (MMA) and n-butyl acrylate (nBA). The adamantyl-substituted methacrylate monomer (1-Ad) showed very low homopolymerization propensity in radical polymerizations, but afforded the alternating copolymer with nBA via copolymerization. The 1-Ad units in the resultant copolymer were quantitatively and selectively transformed into MMA via transesterification with methanol to yield the alternating copolymer of MMA and nBA. Its alternating sequence was clearly demonstrated by a structural analysis via ¹³ C NMR spectroscopy as well as the low reactivity ratios for the 1-Ad and nBA pair. Finally, we verified the superior self-healing ability of the alternating copolymer compared to that of the corresponding 1 : 1 statistical copolymer.

Elucidation of the Alternating Copolymerization Mechanism of Epoxides or Aziridines with Cyclic Anhydrides in the Presence of Halide Salts

Organic halide salts in combination with metal or organic compound are the most common and essential catalysts in ring-opening copolymerizations (ROCOP). However, the role of organic halide salts was neglected. Here, we have uncovered the complex behavior of organic halides in ROCOP of epoxides or aziridine with cyclic anhydride. Coordination of the chain-ends to cations, electron-withdrawing effect, leaving ability of halide atoms, chain-end basicity/nucleophilicity, and terminal steric hindrance cause three types of side reactions: single-site transesterification, substitution, and elimination. Understanding the complex functions of organic halide salts in ROCOP led us to develop highly active and selective aminocyclopropenium chlorides as catalysts/initiators. Adjustable H-bonding interactions of aminocyclopropenium with propagating anions and epoxides create chain-end coordination process that generate highly reactive carboxylate and highly selective alkoxide chain-ends.

Characterization of homogenous acid catalyzed biodiesel production from palm oil: experimental investigation and numerical simulation

Biodiesel is a biological renewable source produced from the conversion of triglycerides to alkyl esters. Palm oil is one of the most used lipid feedstocks for biodiesel production. It becomes necessary to optimize the transesterification reaction parameters to reduce the cost and enhance the quality of biodiesel. This study focuses on the use of homogenous sulfuric acid as a catalyst for the transesterification of palm fatty acids to methyl esters in a batch-scale reactor. A novel examination of transesterification reaction input parameters using the technique for order performance by similarity to ideal solution optimization technique and the effect of these parameters on yield, viscosity, and density of palm biodiesel using 3D surface graphs is investigated in this research. The present optimization approach is implemented to find out the optimum ranking of biodiesel production. From the experimental and numerical simulation, optimum results were observed at the catalyst concentration of 6% (w/w), reaction temperature of 70 °C, the reaction time of 120 min, and alcohol to oil molar ratio of 30:1 at which yield of 95.35%, viscosity of 5.0 cSt, and density of 880 kg/m³ of palm biodiesel were obtained. The different physicochemical properties of produced palm methyl esters are obtained within standards set by international authorities. Selected optimized process parameters can be used for commercial-scale biodiesel production.

Black soldier fly (Hermetia illucens) larvae as potential feedstock for the biodiesel production: Recent advances and challenges

Black soldier fly larvae (BSFL) Hermetia illucens is fastest growing and most promising insect species especially recommended to bring high-fat content as 5th generation bioenergy. The fat content can be fully optimized during the life-cycle of the BSFL through various organic dietary supplements and environmental conditions. Enriched fat can be obtained during the larval stages of the BSF. The presence of high saturated and unsaturated fatty acids in their body helps to produce 70 % of extractable oil which can be converted into biodiesel through transesterification. The first-generation biodiesel process mainly depends on catalytic transesterification, however, BSFL had 94 % of biodiesel production through non-catalytic transesterification. This increases the sustainability of producing biodiesel with less energy input in the process line. Other carbon emitting factors involved in the rearing of BSFL are less than the other biodiesel feedstocks including microalgae, cooking oil, and non-edible oil. Therefore, this review is focused on evaluating the optimum dietary source to produce fatty acid rich larvae and larval growth to accumulate C16-18 fatty acids in larger amounts from agro food waste. The process of optimization and biorefining of lipids using novel techniques have been discussed herein. The sustainability impact was evaluated from the cultivation to biodiesel conversion with greenhouse gas emissions scores in the entire life-cycle of process flow. The state-of-the-art in connecting circular bioeconomy loop in the search for bioenergy was meticulously covered.

Towards integrated sustainable biofuel and chemical production: An application of banana pseudostem ash in the production of biodiesel and recovery of lignin from bamboo leaves

This study investigated an integrated approach to the biowaste transformation and valorization of byproducts. Biochar obtained from the banana pseudostem was calcined to synthesize a heterogeneous catalyst and sustainably prepare a highly alkaline solution. The ash was utilized directly as a heterogeneous catalyst in biodiesel production from waste cooking oil. At the same time, an alkaline solution prepared from the ash was used for delignification and recovery of lignin from bamboo leaves by the hydrothermal reaction. Techniques like Fourier-transform infrared spectroscopy (FTIR), Field emission scanning electron microscopy (FESEM), Brunauer-Emmett-Teller (BET), Transmission electron microscopy (TEM), and Energy dispersive X-ray (EDX) were applied to characterized the catalyst. The alkaline solution was analyzed with Atomic absorption spectroscopy (AAS). The Response surface methodology (RSM) technique was considered for the optimization of different parameters in the transesterification and hydrothermal reaction. Under the optimized condition, waste cooking oil (WCO) to Fatty acid methyl ester (FAME) conversion was 97.56 ± 0.11%, and lignin recovery was 43.20 ± 0.45%. While at the best operating pyrolysis temperature, the liquid fraction yield from the banana pseudostem (500 °C) was 38.10 ± 0.31 wt%. This integrated study approach encourages the inexpensive, sustainable, and environment-friendly pathway for synthesizing catalysts and preparing a highly alkaline solution for the valorization of biowaste into biofuel and biochemicals.

Ball-milling as effective and economical process for biodiesel production under Kraft lignin activated carbon stabilized potassium carbonate

Biodiesel is a typical renewable energy and the previous transesterification processes for biodiesel production mainly focus on thermocatalytic methods. In this paper, the ball-milling process was investigated into the biodiesel production under Kraft lignin activated carbon stabilized K₂CO₃. Biodiesel yield increased to 66 % after only 5 min and reached 100 % within 25 min under optimal ball-milling conditions (0.5 g of the catalyst; methanol/oil molar ratio 18:1; 195 g of ball-mill beads; 1400 rpm; 25 °C). The power demand between the thermocatalytic method and the ball-milling method was also compared. Based on the computation, the ball-milling method has lower power demand than the traditional method (38 vs 201 kWh·mol^-1). Therefore, the ball-milling method is an effective and economical process for biodiesel production.

Biodiesel and activated carbon from arabica spent coffee grounds

This study aims to analyze the potential and characteristics of biodiesel and activated carbon from spent coffee grounds (SCG).•Biodiesel was obtained by extracting oil from SCG using Soxhlet extraction method with n-hexane solvent with an oil yield of 18.14% w/w of dry SCG. Furthermore, the coffee oil was esterified and transesterified to produce biodiesel with 57.32 % yield of coffee oil and higher heating value of 36.69 MJ/kg, density (15°C) of 0.89 g/mL, kinematic viscosity (40°C) of 7.67 mm²/s, acid number of 1.19 mg KOH/g oil.•The residue in form of grounds after oil extraction process was turned into activated carbon using two step activation process. Carbonization process was carried out at 500, 600, 700, and 800°C for 30 minutes and then chemically activated using potassium hydroxide (KOH) at 750°C for 2 hours. As the comparison, activated carbon was also made from SCG without oil extraction process. This study shows that the adsorption capacity of activated carbon made from SCG with oil extraction was better than without oil extraction. The best adsorption of activated carbon was obtained from SCG with oil extraction and carbonized at 700°C with iodine value of 1,224.59 mg/g and methylene blue value of 153.08 mg/g.

Methyl 2-naphthoates with anti-inflammatory activity from Morinda officinalis

Chemical fractionation of the EtOH extract of the roots of a traditional Chinese herb, Morinda officinalis, afforded an array of methyl 2-naphthoate derivatives (1-9) including four pairs of enantiomers (1-4), two pimarane diterpenes and two ursane triterpenoids. Among them, eight compounds (1a/1b-3a/3b, 11 and 13) were reported in the current work for the first time. The structures of the new compounds, including their absolute configurations, were defined by spectroscopic analyses in combination with quantum chemical electronic circular dichroism (ECD) and gauge-independent atomic orbital (GIAO) NMR calculations. All the isolates were evaluated for their inhibitory effect on nitric oxide (NO) production induced by lipopolysaccharide (LPS) in murine RAW264.7 macrophage cells, and the enantiomers 1a and 3b exhibited moderate activity with IC₅₀ values of 41.9 and 26.2 μM. Meanwhile, compound 3b also dose-dependently inhibited the secretion of two pro-inflammatory cytokines TNF-α and IL-6 in the same cell model.

Catalytically Stable Potassium Single-Atom Solid Superbases

Solid superbases can catalyze diverse reactions under mild conditions, while they suffer from aggregation of basic sites and poor stability during recycling. Here we report a new generation of solid superbases derived from K single atoms (SAs) prepared by a tandem redox strategy. The initial redox reaction takes place between base precursor KNO₃ and graphene support, producing K₂ O at 400 °C. Further increasing the temperature to 800 °C, the graphene reduces K₂ O to K anchored by its vacancies, leading to the generation of K SAs (denoted as K₁ /G). The source of basicity in the K₁ /G is K SAs, and neighboring single atoms (NSAs) possess superbasicity, which is different from conventional basicity originated from oxygen and nitrogen atoms. Due to the superbasicity as well as high dispersion and anchoring of basic sites, the K₁ /G shows excellent catalytic activity and stability in transesterification reaction, which is much superior to the reported catalysts.

Membrane reactor based synthesis of biodiesel from Toona ciliata seed oil using barium oxide nano catalyst

Membrane technology has been embraced as a feasible and promising substitute to the traditional technologies employed for biodiesel synthesis which are energy and time consuming. It needs less energy, has high stability, is environmentally friendly, and is simple to operate and control. Therefore, in our current study membrane technology was employed to synthesize biodiesel from Toona ciliate novel and non-edible seed oil. Since Toona ciliata has affluent oil content (33.8%) and is effortlessly and extensively available. In fact, we intended to scrutinize the effects of green synthesized barium oxide nanoparticles for one step transesterification of biodiesel production using membrane technology followed by characterization of prepared catalyst via innovative techniques. Optimal yield of biodiesel attained was 94% at 90 °C for 150 min with methanol to oil molar ratio of 9:1 and amount of about 0.39 wt %. Quantitative analysis of synthesized Toona ciliata oil biodiesel was carried out by advance techniques of Gas chromatography mass spectrometry (GC-MS), Fourier-transform infrared (FTIR) spectroscopy and Nuclear magnetic resonance (NMR) which authorize the synthesis of fatty acid methyl ester compounds using oil from Toona ciliata seeds. Values of Toona ciliata fuel properties for instance flash point (70°C), density (0.89 kg/m³), viscosity (5.25 mm²/s), cloud point (-8°C) and pour point (-11°C) met the specifications of international standards i. e American (ASTM D-6751), European (EN-14214) and China (GB/T 20,828). Subsequently, it is concluded that membrane technology is environmentally friendly and efficient technique for mass-production of sustainable biodiesel using green nano catalyst of barium oxide.

A comparative physicochemical property assessment and techno-economic analysis of biolubricants produced using chemical modification and additive-based routes

Several edible and non-edible oil sources are currently being developed as renewable basestocks for biolubricant production. However, these feedstocks possess undesirable physicochemical properties limiting their lubricant applications. Chemical modification and additive-based routes could be used to modify their properties -suitable for different biolubricant applications. The first part of this study compares how the selected modifications affect the properties of the basestocks. Next, the techno-economic analysis (TEA) was conducted to study 4 selected biolubricants and a potential biolubricant derived from marine microalgae biomass. Oxidative stabilities of chemically modified biolubricants followed the order of epoxidation> triesterification> estolide. Pour points of triesters showed minimal increments and reduced for estolides, whereas epoxidation increased pour points. Estolides exhibit maximum kinematic viscosity increment among chemical modification routes, followed by TMP-transesterification and epoxidation. The oxidative stability of chemically modified biolubricants was higher than additized biolubricants; conversely, the viscosity increments and pour point reductions for additized biolubricants were higher than chemically modified biolubricants. TEA results show that the unit cost for producing 1-kg estolide was the highest among the chemical modification routes. The unit cost per kilogram of jatropha biolubricant produced using the additive-based route was lower than chemically modified biolubricants. Due to a high microalgal oil feedstock cost, the unit cost per kilogram of additized microalgae oil biolubricant was more than the unit cost of additized Jatropha oil. The techno-economic feasibility of biolubricant production from marine microalgal oil could be improved by adopting a biorefinery approach.

Life cycle assessment of biodiesel production by using impregnated magnetic biochar derived from waste palm kernel shell

Biodiesel is renewable, biodegradable, biocompatible (non-toxic) and environmentally friendly, which emits less pollution than traditional fossil-based diesel, making it the most promising and ideal option. However, biodiesel is facing many current issues, mostly related to the utilisation of homogeneous catalytic technology, and this circumstance obstructs its potential development and advancement. Therefore, new pathways for biodiesel production need to be explored, and the aforementioned issues need to be addressed. Recently, a study was conducted on the impregnated magnetic biochar derived from a waste palm kernel shell (PKS) catalyst that can replace conventional catalysts due to its reusability property. Nevertheless, the environmental impacts of impregnated magnetic biochar derived from waste PKS catalyst for biodiesel production are yet to be studied. This study focuses on the evaluation of the life cycle assessment (LCA) of palm-based cooking oil for biodiesel production catalysed by impregnated magnetic biochar derived from waste PKS. Simapro was used in this study to evaluate the impact assessment methodologies. Case 1 (6.64 × 10² Pt) has contributed less to environmental impacts than Case 2 (1.83 × 10³ Pt). This indicates purchasing refined palm oil for biodiesel production may reduce environmental impacts by 64% compared to producing biodiesel from raw fruit bunches. In the midpoint assessment, the transesterification process was identified as the hotspot and marine aquatic ecotoxicity as the highest impact category with a value of 1.00 × 10⁶ kg 1,4-DB eq for 1 tonne of biodiesel produced. The endpoint results showed that Case 1 revealed the greatest impact on the transesterification process, with cumulative damage of 461 Pt. Scenario without processing the raw palm fruit bunches to obtained palm oil was better than Case 2. Further research should be conducted on life cycle cost and sensitivity analysis to evaluate the economic feasibility and promote sustainable biodiesel production.

A validated and optimized method for separation and quantification of total fatty acids by gas chromatography-ion trap mass spectrometry in human plasma

Fatty acids (FAs) are associated with many physiological functions of tissues, and their alteration has been linked with tissue-specific or systemic diseases. The current situation warrants us to have a sensitive and specific method for analysis of total FAs simultaneously from the biological fluid so that the risk prediction, diagnosis or prognosis of the disease can be made effectively. Because of greater sensitivity and resolution, a method of gas chromatography-ion trap mass spectrometry (GC-IT/MS) has been optimized and validated to quantify simultaneously 19 total FAs levels in plasma and compared with GC-triple quadrupole mass spectrometry. FAs have been transesterified by methanolic acetyl chloride to fatty acid methyl esters (FAMEs). A 65 min GC method separated all 19 FAMEs. The calibration curve had good linearity up to 313-922 μM with a correlation coefficient between 0.9882 and 0.9998. The LODs and LOQs of FAMEs were in the range of 0.63 to 9.55 and 2.12 to 31.8 μM, respectively. The method has recovery up to 144 %, stability at 4 °C for 48 h and one freeze-thaw cycle, and good intra-day and inter-day precision. The optimized method has been used to quantify plasma total FAs in type 2 diabetes mellitus patients with and without acute coronary syndrome. Though a significant difference has been found between IT/MS and triple quadrupole mass spectrometry, the GC-IT/MS can help to quantify total FAs in the clinical setting.

A more efficient synthesis and properties of saturated and unsaturated starch esters

This work presents a series of starch esters synthesized via 1,5,7-triazabicyclo[4.4.0]-dec-5-ene (TBD) catalyzed transesterifications in dimethyl sulfoxide (DMSO). The reaction was performed with saturated and unsaturated fatty acids (8, 11, and 18 carbon atoms). The degree of substitution (DS) was raised by purging the reaction flask with nitrogen instead of simply performing the reaction under a nitrogen atmosphere. The increase of DS was most obvious for long-chain fatty acids, as an almost complete DS was observed for starch stearate (2.8) and starch oleate (2.7). The products were characterized by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and X-ray diffraction. Starch esters from unsaturated fatty acids have a lower T_g than their saturated analogues. Moreover, contact angle and moisture uptake measurements showed increased hydrophobicity for all starch esters in comparison to pristine starch. Our results show a more efficient method for synthesizing a biobased material that steers into the direction of a material that could replace conventional plastics.

Biochemical analysis of the replication initiator protein of staphylococcal plasmid pC194

The staphylococcal plasmid pC194 is replicated through the rolling-circle mechanism. Its replication protein RepA has been proposed to initiate replication by making a bond between Y214 and DNA phosphate via transesterification and to terminate it by hydrolyzing DNA with E210 and carrying out strand transfer. We tested this model by examining the catalytic functions of the protein with purified RepA proteins and single-stranded DNA oligomers. The wild-type RepA formed a covalent bond with the DNA phosphate at the predicted initiation site. It hydrolyzed the phosphodiester bond at the site, which activity was found to depend on the presence of a large pseudopalindrome contained in the replication origin. The protein carried out a strand-transfer reaction which mimicked the termination step of replication. A Y214F and an E210A mutant respectively lacked the transesterification and the hydrolytic activity. These results are consistent with the previously proposed model, which was based solely on molecular genetics results. In addition, an E142A mutant was found to lack both activities, suggesting that the residue may coordinate the divalent cation necessary for them. A possible role of the pseudopalindrome in controlling the two activities of RepA during a replication cycle is also discussed.