Glucose Yield Research Articles

Strong adsorption enhances mass transfer and promotes efficient hydrolysis of cellulose to sugar by solid acids

Efficient conversion of cellulose to glucose is a crucial challenge for the energy and materialization of non-food biomass. Solid acids' adsorption strength is essential to affecting mass transfer efficiency. In this study, solid acids with different particle sizes (from 0.25 to 10.10 μm) modified with -OH and -PO3H2 were obtained by hydrothermal method. Hydrolysis of cellulose at 180 °C for 4 h revealed that the particle size of the solid acids was directly proportional to the cellulose conversion (R2 = 0.925). Still, there was no significant correlation with the glucose yield (R2 = 0.632). Eventually, the cellulose conversion reached 98.9 %, with a 30 % glucose yield. The solid acids demonstrated good stability and recoverability. This study fills the gap in the influence of solid acid particle size and reveals the mechanism of strong adsorptive mass transfer and hydrolysis efficiency. It provides the theoretical basis for the design of high-performance solid acids.

Cold plasma/alkaline pretreatment facilitates corn stalk fractionation and valorization towards zero-waste approach

The present study employed alkaline hydrogen peroxide pretreatment coupled with cold plasma for corn stalk’s complex biopolymers fractionation and valorization through enzymatic hydrolysis. This hurdle approach enables the prolonged generation of reactive oxidative species, initiating chemical reactions otherwise hardly possible under ambient conditions. A delignification rate between 76±1 and 86±2 % was obtained under different process parameters in a significantly shorter time compared to conventional alkaline pretreatment. Up to 94±4 % of cellulose in treated biomass was converted to glucose after enzymatic hydrolysis, achieving around 3.5 times higher glucose yield than the raw biomass. Different spectroscopic analyses confirmed specific alterations in the structure of the lignin-rich fraction caused by cold plasma. Micro- and nanoscale lignin particles obtained were rich in total phenolic content, reaching up to 140±20 and 107±12 µg gallic acid equivalents (GAE) per mg of lignin, respectively. The proposed concept of corn stalk fractionation through biorefinery can open new opportunities for valorizing different agricultural waste types.

One-Pot Conversion of Biomass Saccharides to γ-Valerolactone over a Versatile Tin-Containing Material.

The synthesis of biofuel γ-valerolactone (GVL) from accessible biomass is an attractive and challenging goal. Here, we report an efficient, one-pot, and mild strategy for the efficient production of GVL from various biomass saccharides without using any homogeneous acid as a co-catalyst and molecular hydrogen as a hydrogen donor. A versatile porous tin-containing material (Sn(M)-S) was designed as an individual heterogeneous catalyst. As high as 68.4% yield of GVL form glucose was achieved in the presence of ammonia borane as a solid hydrogen donor under mild conditions, with GVL yields of 76.2%, 68.9%, 62.5%, and 52.2% being obtained from fructose, sucrose, cellobiose, and cellulose, respectively. The synergistic effect of Sn and sulfonic acid group in Sn(M)-S not only provides appropriate Lewis acid sites to promote the isomerization of glucose into fructose but also affords abundant Brønsted sites for the following conversion steps. Moreover, Sn(M)-S(1) showed good stability and reusability during consecutive recycles.

A novel experimental approach for the catalytic conversion of lignocellulosic Bambusa bambos to bioethanol

Bambusa bambos (B.B) biomass is cellulose rich lignocellulosic material, containing 47.49% cellulose, 17.49% hemicellulose, 23.56% lignin was used as a potential substrate for bioethanol production. The research paper investigates the use of B.B biomass as a substrate for bio-ethanol production through a two-phase catalytic conversion process. Four water-regulated regimes were identified to optimize the conversion of lignocellulosic biomass to biofuel precursors. The catalytic hydrolysis of B.B using CuCl2 was conducted for 10 hours at 110˚C, in aprotic ionic liquid (1-Butyl-3-methylimidazolium chloride) medium. The concentrations of glucose and 5-hydroxymethylfurfural (5-HMF) were measured while varying the amount of water addition. Water played a crucial role in the conversion of cellulose to glucose and 5-HMF by influencing product yields through the interplay of transport properties like heat conduction and viscosity. The highest glucose yield was achieved at 60.82% when operating at a water inclusion rate of 115.72 µL water/h for a duration of 6 hours at 110˚C. On the other hand, the maximum HMF yield was observed as 5.84% at water inclusion rate of 77.15 µL water/h for 5 hours at 110˚C. Yeast mediated glucose fermentation resulted in a bioethanol concentration of 5.5 mg/mL utilizing 15 mg/mL of catalytically produced glucose at a temperature of 30°C. After catalytic hydrolysis, the ionic liquid was also efficiently recycled for a sustainable economy.

Enhanced cellobiose hydrolysis over fluorine-modulated carbon-based solid acid catalysts

In this study, we synthesized novel carbon-based solid acid catalysts using plasma engineering by integrating sulfonic acid groups as primary catalytic sites and supplemented these with fluorine-containing, chlorine-containing, and other oxygenated functional groups (OFGs). Notably, the catalyst with the fluorine-containing functional groups results superior glucose yield (58.2 %) than that containing only OFGs (37.6 %). Theoretical analysis of the reaction energetics revealed that the cleavage of cellobiose's 1,4-O linkage to form two glucose molecules potentially constitutes the rate-determining step (RDS) in cellobiose hydrolysis. The reaction energy for this RDS was found to increase in the sequence of G–SO3H–F, G–SO3H–Cl, and G-SO3H, consistent with the experimentally obtained catalytic activity trends. Through extensive characterization, including textural analysis, surface chemistry, and density functional theory calculations, we identified that the –F groups are the key to strengthening cellulose–catalyst interactions. This study is the first study to demonstrate the potential of fluorine-modulated carbon-based solid acid catalysts for upgrading cellulosic biomass to value-added compounds.

Investigating the Potential of Grass Biomass (Thysanolaena latifolia) as an Alternative Feedstock for Sugar Platforms and Bioethanol Production

Bioethanol, a lignocellulosic biofuel, has increased energy sustainability and lessened the environmental effects associated with energy production. Thysanolaena latifolia is a common weed found in the northern part of Thailand that is considered non-food biomass, with a high biomass productivity of approximately 10.2 kg/year. Here, we evaluated the potential of T. latifolia biomass as an environmentally friendly material source for producing alternative bioethanol. To this end, we treated the feedstock under mild conditions using various concentrations of phosphoric acid to create ideal conditions for enzymatic hydrolysis. Pretreatment with 75% phosphoric acid yielded the highest solid recovery (55.8 ± 0.6%) and glucans (93.0 ± 0.3%). Additionally, the hydrolysis efficiency and glucose yield of treated biomass were significantly improved. As a result, the liquid hydrolysate from T. latifolia used for ethanol fermentation by Saccharomyces cerevisiae TISTR 5339 generated 8.9 ± 0.0 g/L ethanol. These findings demonstrate that glucose derived from liquid hydrolysate is a promising sustainable carbon source for producing ethanol from T. latifolia feedstock. Thus, using T. latifolia as a feedstock for generating ethanol can improve the efficiency of bioenergy production.

Adequately converting poplar sawdust’s carbohydrates to furfural and glucose by employing acid oxidation pretreatment and solid acid catalysis

The utilization of lignocellulosic biorefinery residue has always been a major obstacle hindering its industrialization. In this work, the acetic acid assisted hydrogen peroxide pretreatment (AHP) and enzymatic hydrolysis was employed to facilitate the efficient bioconversion of poplar sawdust (PS), while simultaneously utilizing the solid acid catalyst (SA) synthesized from enzymatically hydrolyzed PS (EPS) for furfural production from prehydrolysate. It demonstrated that enzymatic hydrolysis of PS achieved a glucose yield of 61.3 %, which can be attributed to the effective removal of xylan and lignin through AHP pretreatment. The structural characterization revealed that SA-EPS exhibited a higher pore density, more acidic sites, and an increased presence of acidic groups compared with SA prepared from PS. Ultimately, the utilization of SA-EPS significantly augmented furfural yield and selectivity to 54.3 % and 64.1 %, respectively. By successfully synthesizing SA using lignin-rich EPS, the value-added benefits and increased efficiency have been achieved in biorefinery processes.

Enhanced Saccharification Yield of Alkali Pretreated Sugarcane Bagasse Utilizing Customized Cellulase Cocktail from Trichoderma harzianum and Trichoderma viride

The experiment was conducted during 2023 at Bioenergy Laboratory, Department of RBEE, College of Agricultural Engineering and Technology, CCSHAU, Hisar, Haryana, India. Compositional changes in sugarcane bagasse subjected to varying concentrations of sodium hydroxide (0.3% to 1.2%), revealing significant increases in glucan content (from 37.13% to 53.81%) alongside decreases in xylan, acid-insoluble lignin, acid-soluble lignin, ash, and other extractives. These changes were validated using microscopic technique SEM, confirming the efficacy of the pretreatment process. The utilization of a customized cellulase cocktail derived from Trichoderma harzianum and Trichoderma viride holds significant promise in enhancing the saccharification from alkali-pretreated sugarcane bagasse. This study investigates the synergistic effects of cellulase enzymes produced by these fungi on the hydrolysis of lignocellulosic biomass. The enzymatic hydrolysis process is optimized by varying enzyme dosages, reaction conditions, and incubation times to maximize the release of fermentable sugars. Results indicate a substantial improvement in saccharification efficiency with the customized cellulase cocktail, highlighting its potential for sustainable biofuel production. The pretreated sugarcane bagasse, when saccharified with Trichoderma harzianum and Trichoderma viride individually, released 254.43 mg g-1 and 325.53 mg g-1 of reducing sugars, respectively, after 40 h of incubation. In contrast, the combined enzymatic cocktail achieved a substantial increase in glucose yields (345.12 mg g-1) at 40 h, showcasing the synergistic effect of the combined enzymatic activity. This research contributes to advancing bioconversion technologies for utilizing lignocellulosic biomass resources efficiently and economically, thus addressing key challenges in sustainable energy production.

Utilization of local corn (Zea Mays) wastes for bioethanol production by separate hydrolysis and fermentation

Maize is the second most-common crop globally. Thus, enormous maize cobs are generated annually from maize processing activities which could serve as a potential and non-edible source for biofuel production. The primary aim of this research was to assess the practicality of producing bioethanol from discarded maize cob through a distinct two-step process referred to as separate hydrolysis and co-fermentation. After a 72-hour fermentation period, the greatest ethanol yield of 66.23 ± 8.35 mL/kg was obtained. This was followed by 54.33 ± 7.27 35 mL/kg after 48 h, and 21.68 ± 2.97 35 mL/kg after 24 h. Importantly, all ethanol yields at different time points exhibited statistical significance at p < 0.05. Moreover, the study revealed a robust positive correlation (r = 0.99, p < 0.01) between glucose and Total reducing Sugars (TRS) yields, and negative correlations were observed between ethanol yield and glucose (r = -0.97, p < 0.05) as well as ethanol and TRS (r = -0.98, p < 0.05). The results indicate the potential of maize cob waste as a valuable resource for bioethanol production. Significant enhancements in operational processes are necessary to enhance the economic feasibility of producing ethanol from maize cobs. Nigeria's utilization of waste for biofuel production is bolstered by substantial policy and financial backing for renewable fuels. The economic viability of ethanol production from maize cobs relies heavily on its competitiveness relative to other waste treatment methods and the effectiveness of policy measures.

Valorization of Corn Straw for Production of Glucose by Two-Step Depolymerization.

Depolymerization of the cellulose part in lignocellulose to glucose is a significant step for lignocellulose valorization. As one of the main by-products of agricultural biomass in crop-producing filed, valorization of corn straw has attracted considerable attention. In this study, a two-step depolymerizing strategy of high-pressure CO2-H2O pretreatment and oxidation-hydrolysis was applied for selective depolymerization of the cellulose component of corn straw to glucose production. Most part of the hemicellulose component could be removed through high-pressure CO2-H2O pretreatment in the presence of low concentration of acetic acid, and then as high as 32.2 % yield of glucose was achieved in water at 170 °C for 6 h without additional catalyst. The active acid sites generated during the partial oxidation of hydroxymethyl groups to carboxyl groups on glucose units of cellulose was shown to be crucial for the efficient valorization of corn straw for glucose production.

Novel ternary deep eutectic solvent fractionation for effective utilization of willow

A novel ternary deep eutectic solvent (TDES), consisting of zinc chloride, ethylene glycol and alpha hydroxy carboxylic acids (i.e., glycolic acid, citric acid and malic acid), was first proposed to effectively fractionate and convert willow (Salix matsudana cv. Zhuliu) into fermentable sugar. In particular, the zinc chloride/ethylene glycol/malic acid (ZnCl2/EG/MA) TDES system showed remarkable fractionation performance with 91.66 % xylan and 90.12 % lignin removals at 130 °C for 1.5 h, resulting in 96.01 % glucose yield in the subsequent enzymatic hydrolysis stage. Moreover, the regenerated lignin showed regular nanoparticle morphology and good antioxidant properties. Even after four recycling, the TDES showed 70.16 % of delignification and 83.70 % glucose yield with the TDES pretreated willow. Overall, this study demonstrated an effective solvent fractionation approach to maximize the utilization of total lignocellulose under mild conditions.

Cascading Recovery of Added-Value Cocoa Bean Shell Fractions Through Autohydrolysis Treatments

AbstractIn this work, an autohydrolysis treatment was applied to cocoa bean shells (CBS) to obtain different potentially added-value fractions rich in phenolic compounds with antioxidant potential and oligosaccharides with potential prebiotic properties. The final residue was enzymatically treated to deliver sugars that can undergo fermentation-based biotransformation. This hydrothermal pretreatment was assessed for maximum temperatures (Tmax) between 120 to 200 °C and severities (S0) between 1.1 and 3.4. The highest oligosaccharide concentration (5.5 g/L) was achieved at S0 of 3.4. The increase of S0 during the process allowed to increase the recovery of interesting bioactive compounds, achieving a maximum TPC and antioxidant activity of 2.8 g/L and 17178.5 µmol Fe2+/L, respectively, when the Tmax reached 200 °C. However, at this temperature, a significant amount of degradation products such as organic acids and HMF was already formed, and a compromise temperature of 160 °C was chosen for further tests. It was possible to obtain a maximum glucose yield of 71% when the pretreated solids were enzymatically hydrolysed. Hence, the use of autohydrolysis, avoiding the use of toxic chemicals, has proved to be a sustainable alternative to obtain different CBS fractions with interesting composition to be potentially employed in multiple sectors.

Efficient enzymatic hydrolysis of active oxygen and solid alkali/dilute sulfuric acid-pretreated corn cob

This work proposed a two-step pretreatment method of cooking with active oxygen and solid alkali (CAOSA) followed by dilute sulfuric acid treatment (DA), to contribute enzymatic hydrolysis of corn cob. The first step, CAOSA pretreatment, removed 83.16 % of the lignin, while the second step, a milder pretreatment with DA further eliminated hemicellulose. After the two-step pretreatment, the cellulose content of the residue reached 66.74 %, and with a solid loading of 5 %, the glucose yield was remarkably high at 98.35 % with a concentration of 36.47 g/L. The optimal conditions of the process were determined as follows: DA with 1 % H2SO4 at a solid-to-liquid ratio of 1:10, a temperature of 110 ℃, and a pretreatment time of 60 min. To confirm the efficacy of the two-step pretreatment, we characterized the samples treated with different methods using X-ray diffraction (XRD), Fourier-transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). The developed method proposes an effective pretreatment and results in the complete enzymatic hydrolysis of corn cob.

Simultaneous production of furfural, lignin and cellulose-rich residue from Eucalyptus urophylla × E. grandis by ChCl/1,2-propanediol/MIBK biphasic system pretreatment

A facile biphasic system composed of choline chloride (ChCl)-based deep eutectic solvent (DES) and methyl isobutyl ketone (MIBK) was developed to realize the furfural production, lignin separation and preparation of fermentable glucose from Eucalyptus in one-pot. Results showed that the ChCl/1,2-propanediol/MIBK system owned the best property to convert hemicelluloses into furfural. Under the optimal conditions (MRChCl:1,2-propanediol = 1:2, raw materials:DES:MIBK ratio = 1:4:8 g/g/mL, 0.075 mol/L AlCl3·6H2O, 140 °C, and 90 min), the furfural yield and glucose yield reached 65.0 and 92.2 %, respectively. Meanwhile, the lignin with low molecular weight (1250–1930 g/mol), low polydispersity (DM = 1.25–1.53) and high purity (only 0.08–2.59 % carbohydrate content) was regenerated from the biphasic system. With the increase of pretreatment temperature, the β-O-4, β-β and β-5 linkages in the regenerated lignin were gradually broken, and the content of phenolic hydroxyl groups increased, but the content of aliphatic hydroxyl groups decreased. This research provides a new strategy for the comprehensive utilization of lignocellulose in biorefinery process.

Enhanced enzymatic hydrolysis of lignocellulosic substrate with less-expensive formulation of homemade cellulase cocktails

This study focused on the efficient production of fermentable sugars from high-solids enzymatic hydrolysis of the lignocellulosic substrate, using homemade cellulase preparation (from China company) combined with surfactants, plant-derived proteins, and accessory enzymes. Results show that various non-ionic and ionic surfactants worked together very effectively, resulting in the 48-h glucose yield of enzymatic hydrolysis increasing by 21.4 %, compared with a single surfactant. The surfactant mixture was particularly competitive at a lower enzyme loading and higher solid content of the enzymatic hydrolysis. Many plant-derived proteins were found to be useful in enzymatic hydrolysis. With the optimized mixture of surfactants, plant-derived protein, and accessory enzymes, the homemade cellulase preparation produced 170 g/L of fermentable sugars (∼ 90 % of the yield) from the enzymatic hydrolysis (2 mg/g dried substrate, 20 % (w/v), 72 h), which was promisingly economic and close to the starchy sugar. The homemade cellulase preparation by formulation with various surfactants and plant-derived proteins supplied a feasible solution for the development of a cost-effective enzymatic hydrolysis process.

An integrated biorefinery strategy for Eucalyptus fractionation and co-producing glucose, furfural, and lignin based on deep eutectic solvent/cyclopentyl methyl ether system

A novel biphasic system containing water-soluble deep eutectic solvent (DES) and cyclopentyl methyl ether (CPME) was developed to treat Eucalyptus for furfural production, extracting lignin and enhancing cellulose enzymatic hydrolysis. Herein effect of DES type, water content in DES, temperature and time on furfural yield in water-soluble DES/CPME pretreatment process was firstly evaluated. A maximum furfural yield of 80.6 % was attained in 10 min at 150 °C with choline chloride (ChCl)/citric acid monohydrate (CAM)/CPME system containing 30 wt% water and 2.5 wt% SnCl4·5H2O, which was higher than that obtained from ChCl/CAM/CPME system without water (55.5 %) and H2O/CPME system (49.7 %). These results demonstrated that the water-soluble DES/CPME system was a powerful method enhancing the furfural production. Under the optimal pretreatment conditions, the delignification and glucose yield were reached to 72.7 % and 94.3 %, respectively. The extracted lignin showed low molecular weight and β-aryl-ether was obviously cleaved. Additionally, water-soluble DES/CPME pretreatment led to a significant removal of hemicelluloses (100.0 %) and lignin (72.7 %) and introduced morphological changes on cell walls, especially from the cell corner (CC) and secondary wall (SW) layers. Overall, this work proposed a practical one-step fractionation strategy for co-producing furfural, lignin and fermentable sugar, providing a way to biorefinery.

Reversible immobilization of cellulase on gelatin for efficient insoluble cellulose hydrolysis

Immobilized enzymes are one of the most common tools used in enzyme engineering, as they can substantially reduce the cost of enzyme isolation and use. However, efficient catalysis of solid substrates using immobilized enzymes is challenging, hydrolysis of insoluble cellulose by immobilized cellulases is a typical example of this problem. In this study, inspired by bees and honeycombs, we prepared gelatin-modified cellulase (BEE) and gelatin hydrogels (HONEYCOMB) to achieve reversible recycling versus release of cellulase through temperature-responsive changes in the triple-stranded helix-like interactions between BEE and HONEYCOMB. At elevated temperatures, BEE was released from HONEYCOMB and participated in hydrolytic saccharification. After 24 h, the glucose yields of both the free enzyme and BEE reached the same level. When the temperature was decreased, BEE recombined with HONEYCOMB to facilitate the effective separation and recycling of BEE from the system. The enzymatic system retained >70 % activity after four reuse cycles. In addition, this system showed good biocompatibility and environmental safety. This method increases the mass transfer capacity and enables easy recovery of immobilized cellulase, thereby serving as a valuable strategy for the immobilization of other enzymes.

Preparation of a magnetic solid acid Fe3O4@PS‐SO3H and its use in hydrolysis of cellulose

AbstractBACKGROUNDIn order to improve the catalytic performance and stability of magnetic solid acid for cellulose hydrolysis in the aqueous phase, this study first modified the surface of magnetite (Fe3O4) nanoparticles (NPs) with oleic acid. Then, in an oil‐in‐water (O/W) emulsion system, polystyrene (PS) was coated on the Fe3O4 NPs through emulsion polymerization. Finally, magnetic solid acid Fe3O4@PS‐SO3H was prepared by sulfonation.RESULTSThe obtained Fe3O4@PS‐SO3H was characterized by transmission electron microscopy, energy‐dispersive X‐ray spectroscopy, infrared, X‐ray diffraction, X‐ray photoelectron spectroscopy and thermogravimetric analysis, and its acid densityand magnetic properties determined. Applied to cellulose hydrolysis, it exhibited 35.28 emu·g−1 saturation magnetization and 3.56 mmol·g−1 maximum acid density. At 140 °C and 1:1 acid to substrate ratio, cellulose hydrolysis with Fe3O4@PS‐SO3H gave a glucose yield of ≤64.14% in 10 h. The solid acid was conveniently recycled with a magnet and reused for further cellulose hydrolysis. It maintained good catalytic activities after five cycles.CONCLUSIONThe magnetic solid acid with a polystyrene backbone prepared by emulsion polymerization exhibits efficient and stable catalytic performance, in line with the trend of green development in ‘bio‐refining’, and lays the foundation for the development of composite solid acids. © 2024 Society of Chemical Industry (SCI).

Co-production of fermentable sugars and highly active lignin from eucalyptus via a mild preprocessing with diethylene glycol and chromic chloride

Eucalyptus was pretreated with diethylene glycol catalyzed by 0.02 mol/L CrCl3 for 10 min, resulting in 91 % delignification and 98 % cellulose recovery, with trace fermentation inhibitors generated. After the mild pretreatment, the accessibility and affinity of cellulase to eucalyptus was enhanced, especially since enzyme adsorption rate increased by 1.6-fold. Therefore, glucose yield of pretreated eucalyptus was 7.9-fold higher than that of untreated eucalyptus after hydrolyzed 48 h, in which the maximum glucose concentration reached 62 g/L from eucalyptus by adding Tween 80. According to the characterization analysis, the structure of the eucalyptus lignin-carbohydrate complexes structure was destroyed during the pretreatment, while lignin fragments was likely reacted with diethylene glycol to form the stabilized aromatic ethers. Moreover, the extracted Deg-lignin exhibited better performances than commercial alkali lignin such as higher fluorescence intensity, less negative surface charge, and lower particle size. The mild pretreatment method with diethylene glycol and CrCl3 provided a promising approach for co-production of fermentable sugars and high activity lignin from lignocellulosic biomass.

Interfacial nanoarchitectonics for enhanced photo-assisted thermo-catalytic conversion of glucose to 5-hydroxymethylfurfural

Photo-assisted thermo-catalytic conversion of glucose to 5-hydroxymethylfurfural (HMF) is one of the most promising ways for channeling solar energy. Photo-assisted thermo-catalytic conversion of glucose and HMF yield were improved with SnO2/Cr-MOFs/Cr(OH)3 catalysts under visible light irradiation at 135 ℃-165 ℃ nitrogen atmosphere. SnO2/Cr-MOFs/Cr(OH)3 afforded relatively high Lewis acidity and Brønsted acidity, which was beneficial for thermo-catalytic conversion of glucose. The light and the interface between SnO2 and Cr-MOFs/Cr(OH)3 assistantly promoted the HMF formation. The photo-generated holes (h+) under light irradiation was the driving force for the formation of “free” protons from water and carboxylic acid in Cr-MOFs, which acted as Brønsted acid sites to promote HMF formation. With 576 mg glucose as the substrate and DMSO as the solvent, 92 % glucose conversion with 43.2 % HMF yield was achieved at 150 ℃ for 2 h under nitrogen atmosphere and 500 W Xe lamp irradiation. The results demonstrate the promise of photo-assisted thermo-catalytic conversion of glucose in the future.