Renewable Feedstock Research Articles

Enhancing diesel engine performance and emissions control with reduced Graphene oxide and Non-Edible biodiesel blends

The growing concern about environmental degradation and the depletion of fossil fuel supplies has prompted experts to investigate alternate and sustainable transportation energy sources. In these circumstances, biodiesel made from renewable feedstock has emerged as a viable environmentally friendly alternative to conventional diesel. This study thoroughly examines the performance and emission characteristics of a 4-stroke diesel engine running on biodiesel blends, including reduced graphene oxide (rGO) nanomaterial. The non-edible biodiesel from the Jatropha curcas plant is utilized, and it is blended in various ratios with conventional diesel, ethanol, and nanomaterial rGO to improve performance and emissions parameters. Torque increased by up to 17 % in rGO DJE02GO25 at 3500 rpm, while Brake Power decreased by 6.3 % in rGO DJE01GO25 at 2600 rpm. Brake Thermal Efficiency decreased by 12.5 % in rGO Blend 1 at 2600 rpm, and Brake-specific fuel consumption decreased by 16.5 % in rGO DJE02GO25 at 3500 rpm. CO2 emissions decreased up to 19.71 % in rGO Blend 10 at 2600 rpm. HC emissions decreased to 94 % in rGO blend 8 at 3500 rpm. Finally, NOx emissions decreased up to 84.78 % in rGO Blend 1 at 2900 rpm. The current study reveals that after adding rGO nanomaterial in biodiesel, there is a significant decrease in NOx and HC emissions.

Simultaneous Production of Biogas and Electricity from Anaerobic Digestion of Pine Needles: Sustainable Energy and Waste Management.

Power scarcity and pollution can be overcome with the use of green energy forms like ethanol, biogas, electricity, hydrogen, etc., especially energy produced from renewable and industrial feedstocks. In hilly areas, pine needles are the most abundant biomass that has a low possibility of valorization due to high lignin content. On the other hand, anaerobic digestion (AD) of lignin and animal waste has low biogas yield due to poor conductivity. This study focuses on the simultaneous production of biogas and electricity through the co-digestion of cow dung and pine needles. The digester was initially established and stabilized in the lab to ensure a continuous supply of inoculum throughout the experiment. The optimization process involved the determination of an ideal cow dung-to-water ratio and selecting the appropriate conductive material that can enhance the energy generation from the feedstock. Afterward, both batch and continuous anaerobic digestion experiments were conducted. The results revealed that the addition of powdered graphite (5 mM), activated charcoal (15 mM), and biochar (25 mM) exhibited maximum voltage of 0.71 ± 0.013 V, 0.56 ± 0.013 V, and 0.49 ± 0.011 V on the 30th, 25th and 20th day of AD, respectively. The batch experiment showed that 5 mM graphite powder enhanced electron transfer in the AD process and generated a voltage of 0.77 ± 0.014 V on the 30th day, indicating an increase of ~1.5-fold as compared to the control (0.56 ± 0.019 V). The results from the continuous AD process showed that the digester with cow dung, pine needle, and a conductive material in combination exhibited the maximum voltage of 0.76 ± 0.012 V on the 21st day of AD, while the digester with cow dung only exhibited a maximum voltage of 0.62 ± 0.015 V on the 22nd day of AD, representing a 1.3-fold increase over the control. Furthermore, the current work used discarded plastic items and electrodes from spent batteries to emphasize waste management and aid in attaining sustainable energy and development goals.

Synthesis, degradation Behavior, and recyclability property of novel bio-based Polyimine thermosets

Given the challenges in recycling, degradation, flammability and environmental protection of most petroleum-based thermosets, it is of great significance to develop degradable, recyclable, and flame-retardant thermosets from renewable feedstocks for material safety and promote sustainable development. Herein, novel Polyimine thermosets (PIts) were prepared from renewable vanillin and their degradation behavior and recyclability properties were systematically investigated. The prepared PIts exhibited excellent thermal properties (Tg: 91–158 °C and T5% above 250 °C), degradability and high monomer recovery rates (above 80 %). Meanwhile, the PIts demonstrated outstanding flame retardancy with a UL-94 V-0 rating achieved by forming noncombustible gas, phosphorus-containing species and nitrogen-containing hexatomic rings. Additionally, these PIts displayed high malleability with Ea ranging from 77.0-118.8 kJ.mol−1 and could be recycled via hot pressing without altering their chemical structure and original mechanical properties. This work presents a new strategy for fabricating bio-based advanced thermosets from renewable resources.

Production of bio-based adipic acid using a combination of engineered Pseudomonas putida strains

Adipic acid is an industrially important dicarboxylic acid and an essential precursor in the synthesis of Nylon-6,6. Due to the environmental impact associated with the current synthetic methods for Nylon-6,6 production, greener alternatives based on renewable and bio-based feedstocks are needed. In the present study, the potential of two Pseudomonas putida strains engineered for muconic acid accumulation was used to produce adipic acid from the lignin-derived aromatic compound guaiacol. This was achieved by expressing genes enabling the conversion of guaiacol to catechol in the first strain, and the conversion of muconic acid to adipic acid via expression of the Bacillus coagulans enoate reductase gene in the second strain. Through process engineering, a 2-step production was designed in which 2.93 mM bio-adipic acid was produced, with a yield of 0.57 mol/mol. This is the first demonstration that process and strain engineering can be combined to obtain a complete bio-based route for adipic acid production from depolymerized lignin compounds using the robust P. putida chassis.

Saccharification of Different Delignified Sawdust Masses from Various Trees Along the Lagos Lagoon in Nigeria

Sawdust, a major waste product of the forestry industry, is accumulating along the Lagos Lagoon in Lagos, Nigeria, without it being effectively managed. Besides its use in The saccharification of sawdust could contribute to the development of renewable energy sources and feedstock for bioproduct development. The process is, however, not that straightforward as variables such as the type of cellulase enzyme, pretreatment of the cellulose substrate, and optimizing of cellulase to cellulose ratio are a few that need to be optimized for the process to be effective in terms of glucose production.manufacturing sound-absorbing boards to reinforce concrete beams and for energy purposes, its potential as a renewable energy source and feedstock for bio-product development has not yet been realized. Cellulose, a glucose biopolymer and structural component of cellulose can be hydrolyzed by a hydrolytic enzyme known as cellulase. During the process, the enzyme breaks the B-1,4-glucosidic bond, which keeps the glucose units together, and by acting on this bond, numerous glucose units are released. As part of sawdust, the cellulose molecule is not freely available for the degradation action of the cellulase enzyme as it is strongly associated with lignin, which acts as bio-glue, keeping cellulose and hemicellulose together. Delignification is an effective technique that was used to make the sawdust from ten different trees along the Lagos Lagoon in Nigeria more susceptible to saccharification by cellulase isolated from the fungus Aspergillus niger. Delignified and non-delignified sawdust masses between 2 mg and 10 mg were incubated with the A. niger cellulase solution (2 mg.mL-1), whereafter, the amount of sugar produced by the cellulase action was determined. The percentage saccharification of each sawdust material was also linked with the amount of sugar produced during cellulase action. From these investigations was concluded that delignification increased sugar production when almost all the masses of different sawdust materials were degraded. It was also observed that the ratio of sawdust mass to enzyme concentration is an important variable that influences the effectiveness of the saccharification process. The percentage saccharification of the various sawdust materials was also determined, and it indicated that the highest percentage of saccharification was not obtained when the highest amount of sawdust was degraded, producing the highest amount of sugar.

Enhanced biohydrogen production from thermally hydrolysed pulp and paper sludge via Al2O3 and Fe3O4 nanoparticles

The growing demand for sustainable and green energy sources has led to increasing interest in biohydrogen production from renewable biomass feedstocks. In this study, pulp and paper sludge (PPS), a widely available waste residue, was thermally treated at different temperatures (90°C, 130°C, and 165°C) for varying durations (15, 30, and 60 min). Thermal hydrolysis of PPS increased the chemical oxygen demand (COD) solubilization from 11 % to 24.7 %, and volatile suspended solids (VSS) solubilization up to 15 % with increasing both hydrolysis temperature and reaction time. The resulting thermally treated samples were then evaluated for biohydrogen production through a batch assay. Among the different thermal treatment conditions, the sample treated at 165°C for 60 min exhibited the highest biohydrogen production potential and yield (1287 mL-H2 and 201 mL-H2/g volatile solids (VS)), which is 72 % higher the control untreated PPS (747 mL-H2 and 117 mL-H2/gVS). To further enhance the biohydrogen yield, this optimal sample was mixed with two types of chemically synthesized nanoparticles, namely aluminium oxide (Al2O3) and magnetite (Fe3O4), at various concentrations (50, 100, and 200 mg/g VS). The addition of nanoparticles significantly influenced the biohydrogen production from the thermal-treated PPS. Remarkably, the batch assay mixed with 200 mg of Fe3O4 nanoparticles per gram of VS demonstrated the highest biohydrogen production potential, compared to the thermally treated PPS (1577 vs. 1226 mL-H2). This finding suggests that the presence of Fe3O4 nanoparticles enhances the biohydrogen production process, possibly through improved microbial activity and substrate accessibility. The results of this study highlight the potential of utilizing PPS, an abundant waste product, as a valuable feedstock for biohydrogen production. Overall, this study contributes to the advancement of green energy technologies and underscores the potential of biohydrogen as a renewable and sustainable energy source.

Low-Cost Ni-W Catalysts Supported on Glucose/Carbon Nanotube Hybrid Carbons for Sustainable Ethylene Glycol Synthesis.

The production of ethylene glycol (EG) from cellulose has garnered significant attention in recent years as an attractive alternative to fossil fuels due to the potential of cellulose as a renewable and sustainable feedstock. In this work, to the best of our knowledge, a series of low-cost Ni-W bimetallic catalysts supported on glucose/carbon nanotube hybrid carbons were synthesised for the first time and employed to transform cellulose into EG. Two different strategies were combined for the preparation of the carbons: the activation and addition of carbon nanotubes (CNTs) to obtain a hybrid material (AG-CNT). The catalytic conversion process proceeded through cellulose hydrolysis to glucose, followed by glucose retro-aldol condensation to glycolaldehyde and its subsequent hydrogenation to EG. Through the optimisation of the catalyst's properties, particularly the metals' content, a good synergistic effect of C-C bond cleavage and hydrogenation capabilities was assured, resulting in the highly selective production of EG. The balance between Ni and W active sites was confirmed to be a crucial parameter. Thus, total cellulose conversion (100%) was achieved with EG yields of 60-62%, which are amongst the best yields ever reported for the catalytic conversion of cellulose into EG via carbon-supported catalysts.

Electrolytic biodiesel production from spent coffee grounds: Optimization through response surface methodology and artificial neural network

BackgroundThe disposal of waste spent coffee grounds (SCG) presents a pressing environmental concern, necessitating effective pre-treatment strategies to mitigate potential damage. Transesterification emerges as a viable solution for converting SCG lipids into biodiesel, offering both environmental and economic benefits. MethodsIn this study, the utilization of SCG as a renewable feedstock for biodiesel production through an innovative electrolysis process has been explored, aiming to address the dual challenges of waste management and sustainable energy production. To obtain maximum conversion of SCG oil to biodiesel, a comprehensive analysis of the fatty acid profile using Gas Chromatography-Mass Spectrometry (GC–MS), was conducted allowing for precise characterization of lipid content. Additionally, Fourier Transform Infrared (FTIR) spectroscopy was employed to categorize functional groups and Nuclear Magnetic Resonance (1H NMR) spectroscopy was utilized to analyze the molecular structure of the SCG oil. Optimization of process parameters namely, catalyst concentration, electrolysis time, and direct current (DC) voltage was performed using Response Surface Methodology (RSM) and Artificial Neural Network (ANN) techniques. The ANN model, with its ability to capture complex nonlinear relationships, was particularly effective in identifying the optimal combination of parameters, thereby maximizing biodiesel yield. Significant findingsThe extracted SCG oil was characterized using FTIR, GC–MS and 1H NMR analysis. The GC- MS analysis of bio-oil has reported 44.6 % Linoleic acid, 31.6 % Palmitic acid. The extracted oil had got significant amount of key saturated and unsaturated fatty acid making it suitable for transesterification process. Through ANN, the optimal combination of parameters for electrolytic transesterification i.e.,0.75 wt% catalyst loading, 2 h electrolysis time, and 40 V DC voltage, yielded the highest biodiesel production (98.32 wt.%). Comparative analysis indicated superior performance of the ANN model (R2 = 0.9931, MAE = 0.123) over RSM (R2 = 0.9636, MAE = 1.546). The artificial neural network (ANN) provided a more accurate forecast of the process yield; however, the RSM model effectively predicted the interactions and significance of the pyrolysis factors. The artificial neural network (ANN) provided a more accurate forecast of the process yield; however, the RSM model effectively predicted the interactions and significance of the pyrolysis factors. Biodiesel characterization via FTIR and 1H NMR analysis showed physiochemical properties within standard limits for SCG biodiesel.

Enrichment of Aquatic Xylan-Degrading Microbial Communities.

The transition towards a sustainable society involves the utilization of lignocellulosic biomass as a renewable feedstock for materials, fuel, and base chemicals. Lignocellulose consists of cellulose, hemicellulose, and lignin, forming a complex, recalcitrant matrix where efficient enzymatic saccharification is pivotal for accessing its valuable components. This study investigated microbial communities from brackish Lauwersmeer Lake, in The Netherlands, as a potential source of xylan-degrading enzymes. Environmental sediment samples were enriched with wheat arabinoxylan (WAX) and beechwood glucuronoxylan (BEX), with enrichment on WAX showing higher bacterial growth and complete xylan degradation compared to BEX. Metagenomic sequencing revealed communities consisting almost entirely of bacteria (>99%) and substantial shifts in composition during the enrichment. The first generation of seven-day enrichments on both xylans led to a high accumulation of Gammaproteobacteria (49% WAX, 84% BEX), which were largely replaced by Alphaproteobacteria (42% WAX, 69% BEX) in the fourth generation. Analysis of the protein function within the sequenced genomes showed elevated levels of genes associated with the carbohydrate catabolic process, specifically targeting arabinose, xylose, and xylan, indicating an adaptation to the primary monosaccharides present in the carbon source. The data open up the possibility of discovering novel xylan-degrading proteins from other sources aside from the thoroughly studied Bacteroidota.

Optimization of design and operation of a digestate treatment cascade for demand side management implementation

Sustainable chemical engineering through demand side management (DSM) and renewable feedstock integration e.g. in biorefineries are key to optimizing the use of fluctuating energy resources and minimizing environmental impact while conserving resources. This contribution presents the results of the economic evaluation of integrating DSM into biofuel biorefineries through a dynamic simulation approach. A previously developed decision support tool for DSM implementation was extended to describe the size of intermediate buffer tanks as a function of oversizing up- and downstream processes. Design optimization of the process cascade determined the oversizing that allows the optimal balance of operational cost reduction through flexibility and capital cost increase through oversizing. Scheduling optimization validated the results of the steady-state optimization and show that, by considering interactions between processes, buffer tank capacity can be reduced, while increasing DSM potential.

Hydrogen Production from Sugarcane Bagasse Pentose Liquor Fermentation Using Different Food/Microorganism and Carbon/Nitrogen Ratios under Mesophilic and Thermophilic Conditions

Hydrogen is a well-known clean energy carrier with a high energetic yield. Its versatility allows it to be produced in diverse ways, including biologically. Specifically, dark fermentation takes advantage of organic wastes, such as agro-industrial residues, to obtain hydrogen. One of these harmful wastes that is poorly discharged into streams is sugarcane bagasse pentose liquor (SBPL). The present study aimed to investigate hydrogen generation from SBPL fermentation in batch reactors by applying different food/microorganism (2–10 F/M) and carbon/nitrogen (10–200 C/N) ratios under mesophilic and thermophilic conditions. Biohydrogen was produced in all pentose liquor experiments along with other soluble microbial products (SMPs): volatile fatty acids (VFAs) (at least 1.38 g L−1 and 1.84 g L−1 by the average of C/N and F/M conditions, respectively) and alcohols (at least 0.67 g L−1 and 0.325 g L−1 by the average of C/N and F/M conditions, respectively). Thermophilic pentose liquor reactors (t-PLRs) showed the highest H2 production (H2 maximum: 1.9 ± 0.06 L in 100 C/N) and hydrogen yield (HY) (1.9 ± 0.54 moles of H2 moles of substrate−1 in 2 F/M) when compared to mesophilic ones (m-PLRs). The main VFA produced was acetate (>0.85 g L−1, considering the average of both nutritional conditions), especially through the butyrate pathway, which was the most common metabolic route of experimental essays. Considering the level of acid dilution used in the pretreatment of bagasse (H2SO4 (1%), 1.1 atm, 120 °C, 60 min), it is unlikely that toxic compounds such as furan derivatives, phenol-like substances (neither was measured), and acetate (<1.0 g L−1) hinder the H2 production in the pentose liquor reactors (PLRs). Sugarcane bagasse pentose liquor fermentation may become a suitable gateway to convert a highly polluting waste into a renewable feedstock through valuable hydrogen production.

Secondary School Students’ Engagement with Environmental Issues via Teaching Approaches Inspired by Green Chemistry

Green chemistry refers to the design and application of practices that prevent pollution and promote environmental sustainability. A set of 12 principles make up the core of the green chemistry philosophy, and, since their emergence, they have been implemented in the educational practice of tertiary education. Over the past few years, the green chemistry approach has started expanding among secondary education as well. This review discusses green chemistry teaching experiences in secondary education as reported in 70 scientific publications (from 2002 to the present) that were identified via a literature search. All identified documents were examined and analyzed to map their green chemistry content and relevant environmental issues, the degree of the connection between the chemistry concepts and environmental issues (“environmentalization”), the implemented teaching-learning approaches, and, when applicable, the achieved learning outcomes. Analysis showed that all 12 green chemistry principles were covered within the identified publications, with the ones referring to prevention and the use of renewable feedstocks being the most frequent. The publications touch upon several environmental issues, with the most frequent being those referring to hazardous chemical waste, alternative energy resources, and recycling. Most of the publications correspond to a medium degree of environmentalization. The inquiry-based, hands-on-based, problem-based, context-based, and socio-scientific issues-based teaching approaches were shown to be the most widely used. Regarding the achieved learning goals, those mostly explored were related to the cognitive and affective domains. This comprehensive review may provide a solid foundation for the organization and design of novel curricula that will integrate green chemistry into education for sustainable development programs in secondary education.

Screening of broad-host expression promoters for shuttle expression vectors in non-conventional yeasts and bacteria

BackgroundNon-conventional yeasts and bacteria gain significance in synthetic biology for their unique metabolic capabilities in converting low-cost renewable feedstocks into valuable products. Improving metabolic pathways and increasing bioproduct yields remain dependent on the strategically use of various promoters in these microbes. The development of broad-spectrum promoter libraries with varying strengths for different hosts is attractive for biosynthetic engineers.ResultsIn this study, five Yarrowia lipolytica constitutive promoters (yl.hp4d, yl.FBA1in, yl.TEF1, yl.TDH1, yl.EXP1) and five Kluyveromyces marxianus constitutive promoters (km.PDC1, km.FBA1, km.TEF1, km.TDH3, km.ENO1) were selected to construct promoter-reporter vectors, utilizing α-amylase and red fluorescent protein (RFP) as reporter genes. The promoters' strengths were systematically characterized across Y. lipolytica, K. marxianus, Pichia pastoris, Escherichia coli, and Corynebacterium glutamicum. We discovered that five K. marxianus promoters can all express genes in Y. lipolytica and that five Y. lipolytica promoters can all express genes in K. marxianus with variable expression strengths. Significantly, the yl.TEF1 and km.TEF1 yeast promoters exhibited their adaptability in P. pastoris, E. coli, and C. glutamicum. In yeast P. pastoris, the yl.TEF1 promoter exhibited substantial expression of both amylase and RFP. In bacteria E. coli and C. glutamicum, the eukaryotic km.TEF1 promoter demonstrated robust expression of RFP. Significantly, in E. coli, The RFP expression strength of the km.TEF1 promoter reached ∼20% of the T7 promoter.ConclusionNon-conventional yeast promoters with diverse and cross-domain applicability have great potential for developing innovative and dynamic regulated systems that can effectively manage carbon flux and enhance target bioproduct synthesis across diverse microbial hosts.Graphical

Biorefinery of Beach Cast Seaweed in Brazil: Renewable Energy and Sustainability

Macroalgae are a natural oceanic resource of inexhaustible abundance for the biomass energy industry with growth rates that are three to four times greater than those of terrestrial plants. The objective of this study was to evaluate the sustainability of macroalgae as biomass for biorefining through two investigations. Firstly, the deposition of macroalgae was sampled through 28 collections on seven beaches in the city of Maceió, Brazil, over a two-year period using a zigzag sampling method, covering a deposition area of 135,000 m2. From this, it was estimated that daily collection would yield 5.03 t/ha of dry biomass. Secondly, the calorific values of macroalgal biomass energy and pellet compounds were calculated. The lower calorific value (8.82 MJ/kg) found from a compound of 13 species analyzed was similar to that of the main biomass used in Brazil to obtain energy, i.e., sugarcane bagasse, which has been evaluated as 8.91 MJ/kg. Macroalgal biomass in the form of condensed energy pellets was found to have a higher calorific value of 20.18 MJ/kg, i.e., 1.2% greater than the average for terrestrial biomass pellets. Based on the results obtained, it was observed that macroalgal biomass has the possibility of becoming a new renewable feedstock with potential for bioenergy. The estimates for the deposition of biomass show possibilities for producing biofuels from marine algal raw material, which provides scope for creating another sustainable alternative for global energy issues with a reduction in environmental problems.

A rapid chemical method for production of xylitol from D-xylose as a renewable feedstock from spent aromatic waste

Xylitol is occurring naturally as a minor constituent in many fruits and vegetables. Commercially, xylitol is produced by chemical methods from D-xylose for application as an alternative sweetener in food and pharmaceutical products. Although biomass-derived xylose can be used as a potential substrate for xylitol production, its prerequisite purification before a catalytic hydrogenation directly impacts the production cost. In addition, the isolation of xylose falls under a routine pretreatment activity during conversion of biomass to platform chemicals. The resulting hydrolysate often exhibits a low concentration of xylose and other monosaccharides. Concentrating the hydrolysate to a desired level for conversion to xylitol under chemical/biological methods increases the expenditure cost. Many times, concentration by heating may cause the degradation of contained sugars in the hydrolysate. Therefore, this study has been carried out to obtain a mixture of C5/6 sugars, predominantly the D-xylose in a solid dry form (∼10 % yield, >98 % purity) directly from acid hydrolysate of spent aromatic waste. Biomass-derived D-xylose was further transformed to xylitol (100 % conversion) by a fast (10 min), efficient, and solvent-free chemical approach using a modified sodium borohydride (NaBH4) catalyst on a wet silica (SiO2) support at RT. All reagents and solvents used in the process were recovered and recycled, leading to the minimal waste generation.

Synthesis and characterization of hierarchically porous carbon anodes from furfural biorefinery residues for sustainable lithium-ion batteries

This study aims to valorize abundant lignocellulosic residues from furfural biorefineries into hierarchically porous carbon anodes for sustainable lithium-ion batteries (LIBs). Simultaneously, it addresses the growing demand for high-performance anode materials by leveraging renewable waste feedstocks. Sugarcane bagasse waste residues obtained after furfural extraction were used as the precursor. The furfural-derived bagasse residue (FDBR) underwent pyrolysis at 700 °C to produce a carbon-rich char, which was further activated using KOH and steam at 900 °C for 15–60 minutes to enhance porosity development. Comprehensive physicochemical characterizations, including proximate analysis, N2 adsorption-desorption, SEM-EDX, FTIR, and TGA/DTG, and Raman spectroscopy were performed to evaluate the properties of the synthesized activated carbons. The results demonstrated the successful generation of high surface area (405.8 m2/g) activated carbons with a hierarchical pore structure comprising micropores and mesopores. SEM and EDX analyses revealed a uniform, porous morphology enriched with 10.41 % at oxygen-containing functional groups. FTIR spectra confirmed the presence of hydroxyls, carbonyls, and carboxylic acid groups, beneficial for pseudocapacitive charge storage. The Raman analysis revealed a highly disordered and amorphous carbon structure with a significant concentration of defects, as evidenced by a high-intensity ratio (ID/IG ≈ 1.2–1.4) of the disordered carbon band to the graphitic band. The activated carbons exhibited a high initial discharge capacity of 1055 mAh/g in lithium half-cells, significantly exceeding the theoretical limit of commercial graphite anodes (372 mAh/g). This superior capacity was attributed to the high surface area, hierarchical porosity, and pseudocapacitive contributions from the oxygen functionalities. However, rapid capacity fading from 1055 to ∼250 mAh/g was observed over 100 cycles at a C/2 rate. The capacity retention stabilized at ∼88 % after 47 cycles, indicating irreversible capacity losses. These limitations were ascribed to the disordered amorphous structure, instability of the solid-electrolyte interphase, lithium trapping by oxygen groups, and structural changes during cycling. Optimizing activation conditions, incorporating conductive additives/coatings, exploring alternative binders, and surface functionalization are proposed to improve long-term cycling stability. Overall, this study demonstrates the feasibility of upcycling furfural biorefinery waste into sustainable LIB anodes while highlighting challenges and potential solutions for enhancing their electrochemical performance.

Exploring the Barrier Property of High-Performance Polyurethane-Silica-Lignin Coatings on Carbon Steel

The use of lignin in anticorrosive coatings has provided efficient corrosion protection to metallic alloys.1,2 We have combined lignin-based polyurethane (PU) with silica to produce eco-friendly anticorrosive coatings with high anticorrosive performance, mechanical strength and bactericidal action.3 The PU was synthesized from methyl diphenyl diisocyanate (MDI), glycerol and lignin; the PU pre-polymer was functionalized with APTES to later form a hybrid with the polysilanol network from TEOS. The reference coating4 was prepared using 100% glycerol (PU-Si-0Lig) as the polyol source, while the other two specimens contain glycerol and 0.2 g (Pu-Si-0.2Lig) or 0.4 g (Pu-Si-0.4Lig) of lignin, keeping the predetermined proportion NCO:OH = 1.16. The incorporation of lignin into the polymer matrix led to an increase in the thermal stability (295 to 304 °C), smoothness of the coating surface (4.3 to 1.7 nm) and improvement of the coating mechanical properties, such as coating hardness (362 to 376 MPa). In addition, the lignin-containing coatings present bactericidal activity against Escherichia coli. The corrosion protection of the PU-Si-Lignin hybrid coatings deposited on carbon steel was analyzed by electrochemical impedance spectroscopy (EIS) in 3.5 wt.% NaCl at room temperature. The tests were conducted in a three-electrode cell, consisting of the coated carbon steel substrate as the working electrode, a platinum mesh as a counter electrode, and an Ag|AgCl|KClsat as the reference electrode. PU-Si-0Lig and PU-Si-0.2Lig present fair corrosion protection with low-frequency impedance |Zlf| values around 106 Ω.cm2 after immersion for up to 14 days. Conversely, PU-Si-0.4Lig presents |Zlf| ~ 1010 Ω.cm2, phase angle near -90 ° over seven frequency decades, and a lifespan of 100 days immersed in seawater. The equivalent electric circuit (EEC) used to fit the PU-Si-0.4Lig revealed that the EIS data of the initial 14 days can be represented by a model containing only one time constant. This means the coating has a highly capacitive behavior with insignificant water uptake in the first two weeks. Altogether, these results demonstrated the potential of PU-Si-Lig coating to be applied as an efficient anticorrosive barrier with enhanced mechanical and antibacterial properties.Acknowledgements: This work was supported by the Brazilian funding agencies CNPq, FAPESP, CAPES and PROPe UNESP.Keywords: Renewable feedstock, green coating, PU-silica, lignin, corrosion protection.(1) Harb, S. V.; Cerrutti, B. M.; Pulcinelli, S. H.; Santilli, C. V.; Hammer, P. Siloxane–PMMA Hybrid Anti-Corrosion Coatings Reinforced by Lignin. Surf Coat Technol 2015, 275, 9–16. https://doi.org/http://dx.doi.org/10.1016/j.surfcoat.2015.05.002.(2) Cao, Y.; Liu, Z.; Zheng, B.; Ou, R.; Fan, Q.; Li, L.; Guo, C.; Liu, T.; Wang, Q. Synthesis of Lignin-Based Polyols via Thiol-Ene Chemistry for High-Performance Polyurethane Anticorrosive Coating. Compos B Eng 2020, 200, 108295. https://doi.org/https://doi.org/10.1016/j.compositesb.2020.108295.(3) Alinejad, M.; Henry, C.; Nikafshar, S.; Gondaliya, A.; Bagheri, S.; Chen, N.; Singh, S. K.; Hodge, D. B.; Nejad, M. Lignin-Based Polyurethanes: Opportunities for Bio-Based Foams, Elastomers, Coatings and Adhesives. Polymers (Basel) 2019, 11 (7). https://doi.org/10.3390/polym11071202.(4) Braz, Á. G.; Pochapski, D. J.; Pulcinelli, S. H.; Santilli, C. V. Effects of Curing Temperature and Silica Content on the Structure and Properties of a Sol–Gel PU-Silica Hybrid Coating for Corrosion Protection. ACS Applied Engineering Materials 2023, 1 (7), 1739–1751. https://doi.org/10.1021/acsaenm.3c00148.

Accelerated Development and Optimization of Adiponitrile Production via Kolbe Electrolysis of Biomass-Derived Precursors

Environmental and societal pressures are demanding a transition from fossil-based resources to renewable and sustainable feedstocks for the production of materials. In this context, biomass streams emerge as scalable candidates for creating sustainable chemicals. Electrocatalytic transformation of biomass can facilitate the production of chemicals under mild conditions and can be easily integrated with renewable energy sources. These transformations could lead to the production of sustainable monomers and polymers from biomass, significantly enhancing the sustainability of plastics production. Amongst a large number of plastics manufactured by the chemical industry, Nylon 6,6 is one of the most important fossil-derived polymers for the production of high-performance textiles and structural materials. Central to Nylon 6,6 production is adiponitrile (ADN), predominantly synthesized via energy-intensive thermochemical processes. An alternative route, electrochemical hydrodimerization of acrylonitrile (AN), although successful, still depends on fossil feedstocks. A promising sustainable source for ADN is renewable glutamic acid, derived from hydrolysis of waste proteins.1,2 This process involves transforming glutamic acid to 3-cyanopropanoic acid (CPA) and then to ADN through Kolbe electrolysis, a reaction with a historical background and multiple pathways. Our study utilizes an electrochemical reaction engineering approach to examine the Kolbe electrolysis of CPA to ADN and AN, focusing on a hierarchical research methodology. This approach allowed us to simultaneously accelerate the exploration of numerous reaction parameters while also conducting detailed studies under optimal conditions. This method has enabled us to gain deeper insights into the factors controlling reaction selectivity. We discovered that platinum electrodes favor ADN formation, with selectivity increasing at higher current densities. Optimal CPA concentrations, the presence of larger alkali cations, solvent composition, and controlled pH levels significantly influence ADN production, reducing side reactions such as the oxygen evolution reaction (OER). When using graphite electrodes, an increase in AN production was observed, with the solvent composition playing a crucial role in determining the rate of ADN formation. Our investigation has led to a deeper understanding of the electrochemical conversion of CPA to ADN, revealing key parameters that influence reaction selectivity and rate. The insights obtained from this study are not only pivotal for the specific case of ADN production but also have broader implications for a range of electrochemical decarboxylation reactions. The hierarchical research approach employed here demonstrates its potential for speeding the development of sustainable electrochemical processes. Our insights and methodology used for the electrosynthesis of ADN from biomass-derived feedstocks can be deployed to the deployed to the development of other biomass transformations advancing our ability to produce essential chemicals sustainably.

Electrocatalytic Upgrading of Biomass-Derived Compounds for Biofuel Production

Biomass fast pyrolysis liquid (also known as bio-oil) is considered to be one of the most promising renewable carbon feedstocks. However, fresh pyrolyzed bio-oil is acidic and corrosive and contains large amounts of carbonyl and phenolic compounds produced by polymerization under acidic conditions. This work primarily utilizes an electrochemical conversion strategy using only earth-abundant metal catalysts to achieve the carbonyl hydrogenation process. The results show that upgrading this process produces biofuels with greater stability and higher specific energy. In addition to analyzing the chemical implications of this conversion strategy, this work will also discuss why electrocatalytic conversion is a promising technology path for biofuels and fine chemicals. Reference Huang, S., Lam, C. H.* et al. (2022). "The Structural Phase Effect of MoS2 in Controlling the Reaction Selectivity between Electrocatalytic Hydrogenation and Dimerization of Furfural." ACS Catalysis 12(18): 11340-11354.Huang, S., Lam, C. H.* et al. (2022). "MoS2-Catalyzed Selective Electrocatalytic Hydrogenation of Aromatic Aldehydes in an Aqueous Environment." Green Chemistry.Tu, Q., Lam, C. H.* et al. (2021). "Electrocatalysis for Chemical and Fuel Production: Investigating Climate Change Mitigation Potential and Economic Feasibility." Environmental Science & Technology 55(5): 3240-3249.Garedew, M., Lam, C. H.* et al. (2020). "Greener Routes to Biomass Waste Valorization: Lignin Transformation Through Electrocatalysis for Renewable Chemicals and Fuels Production." ChemSusChem 13(17): 4214-4237. Lam, C. H., et al. (2017). "Towards sustainable hydrocarbon fuels with biomass fast pyrolysis oil and electrocatalytic upgrading." Sustainable Energy & Fuels 1(2): 258-266. Figure 1

Heterogeneous Electrosynthesis of Nitriles through Coupling of Primary Alcohols and Ammonia on Noble-Metal-Free Monometallic Catalyst

Despite increasing interest devoted to the electrocatalytic refinery of renewable feedstocks for the sustainable production of value-added chemicals, the direct electrosynthesis of nitriles from biomass-derived alcohols is rarely studied. Nitriles are highly versatile intermediates for producing a wide range of chemicals, including biological materials, pharmaceuticals and polymers. The conventional chemical methods for nitrile synthesis, such as the Sandmeyer and the Rosenmund-von Braun reactions, are not benign as they utilize toxic starting materials, require severe reaction conditions and generate large amounts of chemical waste. More environmentally friendly chemical routes using alcohols and ammonia as the substrates, via oxidation or oxidant-free dehydrogenation coupled with imination, have been recently reported. However, they face certain issues, including the need for oxidants or high reaction temperatures, as well as poor selectivity due to possible over-oxidation and other side reactions. On the electrocatalysis front, the synthesis of hydrogen cyanide, an analogue of nitrile, has been demonstrated using methanol and ammonia as the substrates, albeit at an elevated temperature with costly solid electrolytes. Here, we report a benign one-pot synthesis of nitriles from primary alcohols and ammonia, in the presence of a simple nickel electrocatalyst under ambient temperature using aqueous electrolytes without the need for oxidants.In the initial screening stage, nine species of metal-based catalysts which were reported to be active in the thermocatalytic pathway of the same reaction, including Mn, Fe, Co, Ni, Cu, Zn, Ru, Pd and Pt, as well as carbon paper were studied using benzyl alcohol (BnOH) as a model compound (Figure 1a). Among them, Ni foam, bearing good resistances towards dissolution under oxidative potentials and poisoning by ammonia, has the capacity to produce benzonitrile as the main product under lower overpotentials. Several control experiments were conducted, revealing that the reaction pathway proceeds via two sequential steps: (1) The alcohol first undergoes dehydrogenation to produce an aldehyde intermediate, which equilibrates in the presence of ammonia to afford the corresponding imine. (2) The imine is subsequently dehydrogenated to form the nitrile product (Figure 1b). Based on the linear sweep voltammetry (LSV) results and in-situ Raman analyses (Figure 1c, d), we propose that the in-situ formed NiII/NiIII redox species serve as the active sites for the nitrile production through a hydrogen atom transfer (HAT) mechanism. The influences of applied potentials, alcohol/ammonia concentrations and pH on the reaction were also systematically investigated. A high benzonitrile faradaic efficiency (FE) of 63.0% and a formation rate of 90.8 mmol m-2 h-1 were achieved at applied potentials of 1.375 V and 1.425 V vs. RHE, respectively, under the optimum conditions: 20 mM BnOH, 1 M ammonia and pH 13 (Figure 1e). Subsequently, kinetic studies and mathematical modelling were performed, suggesting that the dehydrogenation from alcohol to aldehyde displays the smallest rate constant. Isotope labelling experiments (Figure 1f) further confirmed that the rate-determining step (RDS) likely involves the cleavage of α-carbon C-H bond in the hydroxyl group of the alcohol. Encouragingly, various aromatic, aliphatic and heterocyclic primary alcohols were transformed to the corresponding nitriles, exhibiting the broad feasibility of our strategy. This study offers a promising electrocatalytic system for the low-cost, green synthesis of high-value nitriles in the chemical industry. Figure 1