Lignin Reduction Research Articles

Effect of drought stress on morpho-physiological characteristics, nutritive value, and water-use efficiency of sorghum [Sorghum bicolor (L.) Moench] varieties under various irrigation systems.

Addressing water scarcity and the need for high-quality forage in arid regions necessitates the development of efficient irrigation techniques. This study assesses the impact of various irrigation methods on the performance and irrigation water-use efficiency (IWUE) of sorghum cultivars under water-deficit conditions in a semi-arid region of Iran during the 2019 and 2020 cropping seasons. Three irrigation methods-variable alternate furrow irrigation (AFI), fixed alternate furrow irrigation (FFI), and conventional furrow irrigation (CFI)-were evaluated alongside three levels of drought stress (severe stress: I50, moderate stress: I75, and full irrigation: I100) and two sorghum cultivars. The results indicated that increasing drought stress, as well as the transition from CFI to AFI and FFI, led to reductions in metabolizable energy yield (MEY), plant height, cellulose, hemicellulose, and lignin. Conversely, there were increases in leaf-to-stem ratio, digestible organic matter, metabolizable energy content, crude protein content, and IWUE for metabolizable energy production (IWUEME). The highest MEY (211.68 GJ ha-1) was recorded under CFI×I100, albeit at the expense of maximum water consumption (7261 m3 ha-1). Meanwhile, the AFI×I50 and FFI×I50 treatments exhibited the highest IWUEME (44.46 MJ m-3) and metabolizable energy content (8.736 MJ kg-1), respectively, while conserving over 60% of water. Hybrid Speedfeed outperformed in forage yield and IWUEME, while cultivar Pegah excelled in forage quality. Transitioning from CFI to AFI or FFI resulted in decreased forage yield but improved forage quality and IWUEME. Principal component analysis revealed that leaf-to-stem ratio and plant height serve as effective indicators for assessing the nutritive value and forage yield of sorghum, respectively. Considering the overall results, cultivating the hybrid Speedfeed under AFI×I75 conditions is recommended for optimal water utilization, achieving satisfactory forage yield and quality, and enhancing IWUE.

Comparative Analysis on Microwave and Pressure Cooker Pre-Treatment of Lignocellulosic Biomass in Glucose Production via Fungal Treatment

Oil Palm Empty Fruit Bunch (OPEFB) is lignocellulosic biomass waste generated from palm oil processing industries. Due to its significant compositions of cellulose, hemicellulose, and lignin, OPEFB can be further utilized and converted into value-added chemical products which can be used as alternative energy. Hence, the focus of this research is to analyze the effect of microwave pre-treatment (MP) and pressure cooker pre-treatment (PCP) parameters on OPEFB lignin reduction. The treated OPEFB was directly processed using two serial fungal treatment processes. The first fungal treatment process (FT-1) was to maximize the OPEFB lignin removal while the second fungal treatment process (FT-2) was to maximize the glucose production. Combination of microbes such as Phanerochaete chrysosporium, Trichoderma harzianum, Aspergillus niger, and Tricodherma viride was used for both fungal treatment processes. The OPEFB passing 25-mesh screening was used as raw materials. The raw materials mixed with 0.05 w/w NaOH pellets and water to achieve a concentration ratio of 3/50 (w/v) were pre-treated with either MP or PCP. Subsequently, the slurry produced from the pre-treatment process was introduced to FT-1 (P. chrysosporium for 5 days) and finally to FT-2 (T. harzianum, A. niger and T. viride for 4 days). The compositions of lignin, cellulose, hemicellulose, and glucose were analyzed at each process transition and the end of the whole process. It was observed that PCP (60 mins) was the best pre-treatment process with 39.23%-w of lignin removed. On the other hand, combination of MP (150 watts, 60 mins) was followed with FT-1 removed 66.67%-w of lignin. Only around 38.37%-w of lignin was removed when using the whole process, e.g., MP (150 watts, 60 mins), FT-1, and FT-2. The highest composition of glucose, ca. 131.02%-w, was obtained when 40-min PCP followed with FT-1 and FT-2 was applied. The obtained results exhibited that large lignin removal did not necessarily promote high glucose yield in the final product as observed in the 60-min PCP, e.g., P. chrysosporium consumed not only lignin but also presumably hemicellulose and cellulose.

Statistical Optimization of Tween-80-Assisted Potassium Hydroxide Pretreatment and Enzymatic Hydrolysis for Enhancing Sugar Yields from Corn Cob

With the addition of Tween 80, potassium hydroxide pretreatment and enzymatic hydrolysis were statistically optimized to maximize sugar yields from corn cob (CC). The results indicated that the sugar yields from CC could be influenced significantly by the potassium hydroxide concentration, temperature and time during pretreatment. The optimized pretreatment conditions were as follows: potassium hydroxide, 46 g·L−1; Tween 80, 3.0 g·L−1; solid dose, 200 g·L−1; temperature, 78 °C; and time, 50 min. After optimization, the lignin reduction and recoveries of cellulose and hemicellulose were 89.7%, 97.8% and 68.0%, respectively. In addition, sugar production could also be influenced by the biomass loading, enzyme loading and reaction time. A maximal glucose production (518.48 mg·gds−1, milligrams per gram of dry substrate) and xylose production (351.14 mg·gds−1), 97.2% cellulose conversion and 82.9% hemicellulose conversion from CC could be obtained when the biomass loading was 195 g·L−1 and the enzyme loading was 8.9 FPU·gds−1 (filter paper activity units per gram of dry substrate) and when the Tween 80 concentration was 3.0 g·L−1 at 50 °C for 30.4 h during hydrolysis. This is the first systematic study of combined Tween 80 pretreatment of CC by potassium hydroxide and hydrolysis of CC by cellulase preparation to increase sugar production.

Preparation and characterization of snake plant fiber reinforced composite: A sustainable utilization of biowaste

AbstractNatural fibers are one of the most attractive materials in biocomposites due to their potential for sustainability. This study aims to prepare sustainable composite materials using fibers from Sansevieria trifasciata (snake plant) and to investigate their mechanical, morphological, and water absorption properties. The composite was prepared with epoxy resin through a manual hand lay‐up process, maintaining standard parameters with changeable reinforcement (10%, 20%, and 30%). The mechanical properties (tensile, impact, and flexural strength), Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), and water absorbency of the composites were evaluated. The result showed that the tensile strength, flexural strength, and impact resistance of the composites are 6.99 MPa, 10.77 MPa, and 14 J, respectively, for 30% fiber components, which are significantly higher than other composite materials. The SEM analysis showed a strong interfacial bond between the snake plant fiber and the epoxy resin. The FTIR analysis revealed a reduction in hemicellulose and lignin and an improvement in the interfacial adhesion between snake plant fiber and epoxy resin. The composites also demonstrated time‐dependent increases in water absorption, with the sample containing 30% fiber components showing the best absorbency performance at 0.88%.Highlights A study is being conducted on the effective and sustainable use of biowaste. The composite materials loaded with 30% fibers had significantly high tensile strength, flexural strength, and impact resistance. The SEM analysis of snake plant fiber‐reinforced polymer composite showed a strong interfacial bond between fiber and epoxy resin. The FTIR analysis of the composite revealed the reduction of hemicellulose and lignin. The use of non‐renewable materials is reduced, and eco‐friendliness is promoted.

Agro-wastes bioconvertion by an Amazonian isolate of Ganoderma sp. and a commercial strain of Ganoderma lingzhi

Agro-industrial wastes discarded in nature may cause environmental damage; however, they have potential for application in mushroom cultivation, making it possible to bioconvert these wastes into materials of higher added value with the possibility of application in different industrial segments. The aim of this work was to compare the biotransformation potential of Amazon lignocellulosic wastes by Ganoderma sp. (isolated in the Amazon) and G. lingzhi (a commercial strain). The mushrooms were grown in açaí (Euterpe sp.), guaruba-cedro (Vochysia maxima), and three different batches of marupá (Simarouba amara) wastes. Initial substrates (IS) and spent mushroom substrates (SMS) were subjected to physico-chemical analysis, scanning electron microscopy (SEM), X-ray diffraction (XRD), and crystallinity index (CrI). A trend to decrease moisture, ash, lipids, carbon, and cellulose levels was observed in SMS. It is highlighted that after the growth of G. lingzhi and Ganoderma sp., there was a reduction in lignin by 29% and 48%, respectively, while there was an average increase in nitrogen content of 44% and 142% in SMS, respectively. SEM analysis showed visible loosening of lignocellulose fibers; XRD showed a characteristic peak of amorphous cellulose; and the CrI highlighted the coexistence of ordered and disordered regions. Thus, the mushrooms have shown potential in the bioconversion of Amazon wastes, notably for Ganoderma sp., which has demonstrated high potential for delignification and fortification of waste playing potential for application in the cellulose and animal feed industries.

Novel Pre-treatment for Lignocellulosic Biomass Delignification Using Alkaline-Assisted Ohmic Heating

Lignocellulosic biomass (LCB) is a common substrate for biogas and bioethanol production due to its significant properties and abundance. However, it has a unique recalcitrant structure that can inhibit the production of biogas, which necessitates pre-treatment of the substrate to obtain higher cellulose or sugars ready for microbial hydrolysis in producing biogas. In this study, a novel approach for empty fruit bunch (EFB) pre-treatment has been made: ohmic heating pre-treatment. This method is conventionally used in the food industry for pasteurization and extraction. It involves electric current and resistance inside the material that releases heat (Joule effect). A preliminary study has been done to figure out the potential of alkaline assisted with ohmic heating (AA-OH) pre-treatment for EFB. Lignin reduction for AA-OH EFB is higher than EFB that undergoes only size reduction (SR) pre-treatment, which are 15.54% and 11.51%, respectively. After confirming the potential of ohmic heating as one of the pre-treatment methods for EFB, three parameters were investigated (reaction time, temperature, and solvent concentration) by one factor at a time (OFAT) testing to obtain the optimum condition for AA-OH pre-treatment. The optimal condition for achieving a high reduction in lignin (86.9%) and hemicellulose (75%) while also showing a significant increase in cellulose (63.2%), which is desirable for the fermentation process, is achieved by using 4% w/v of NaOH, ohmic-heated at a temperature of 120°C for 25 minutes. To sum up, this developed ohmic heating pre-treatment technique can be applied to LCB prior to biogas or bioethanol production.

Simultaneous suppression of lignin, tricin and wall-bound phenolic biosynthesis via the expression of monolignol 4-O-methyltransferases in rice.

Grass lignocelluloses feature complex compositions and structures. In addition to the presence of conventional lignin units from monolignols, acylated monolignols and flavonoid tricin also incorporate into lignin polymer; moreover, hydroxycinnamates, particularly ferulate, cross-link arabinoxylan chains with each other and/or with lignin polymers. These structural complexities make grass lignocellulosics difficult to optimize for effective agro-industrial applications. In the present study, we assess the applications of two engineered monolignol 4-O-methyltransferases (MOMTs) in modifying rice lignocellulosic properties. Two MOMTs confer regiospecific para-methylation of monolignols but with different catalytic preferences. The expression of MOMTs in rice resulted in differential but drastic suppression of lignin deposition, showing more than 50% decrease in guaiacyl lignin and up to an 90% reduction in syringyl lignin in transgenic lines. Moreover, the levels of arabinoxylan-bound ferulate were reduced by up to 50%, and the levels of tricin in lignin fraction were also substantially reduced. Concomitantly, up to 11 μmol/g of the methanol-extractable 4-O-methylated ferulic acid and 5-7 μmol/g 4-O-methylated sinapic acid were accumulated in MOMT transgenic lines. Both MOMTs in vitro displayed discernible substrate promiscuity towards a range of phenolics in addition to the dominant substrate monolignols, which partially explains their broad effects on grass phenolic biosynthesis. The cell wall structural and compositional changes resulted in up to 30% increase in saccharification yield of the de-starched rice straw biomass after diluted acid-pretreatment. These results demonstrate an effective strategy to tailor complex grass cell walls to generate improved cellulosic feedstocks for the fermentable sugar-based production of biofuel and bio-chemicals.

Unraveling Electrochemical Lignin Degradation in Organic Solvent for Production of Valuable Fuels and Chemicals

Lignin is the second most abundant biopolymer in nature after cellulose. Due to its distinctive aromatic backbone, it is also one of the most unique biopolymers. The aromatic components in lignin provide structural support to plants and comprises about 30% of the plant material. These aromatic groups can be used to produce renewable aromatic compounds. Also, these aromatic compounds can be used to produce biofuels which can be promising alternative to fossil-based fuels and chemicals. Besides, from previous studies it is found that about 40 to 60 million tons of lignin are generated from pulp and paper industry, mostly as wastes. So, developing novel and attractive strategies for fragmentation of lignin is gaining increased interest among scientific community for valorizing this underexploited material. Also, by valorizing lignin the sustainability of biorefinery and paper industry can be enhanced. However, the present technologies used for degradation of lignin generally requires the use of metallic catalysts at high temperatures and harsh reaction conditions. As a result, catalyst recovery and decomposition often become difficult under such harsh conditions and the process becomes impractical. Also, these technologies suffer from poor selectivity and usually produce the desired fragmentation products in low yields. Compared to the thermocatalytic transformation of lignin, electrocatalytic approaches have several advantages like it is environmentally friendly, have mild reaction conditions and the cost is low. Besides, there is a lack of studies incorporating electrocatalytic oxidation and reduction of lignin in organic solvent. In this project, the main goal was to overcome the challenge of using isolated lignin from various industrial processes by electrochemical depolymerization of lignin in organic solvent like tetrahydrofuran. Tetrahydrofuran is mainly used in Co-solvent Enhanced Lignocellulosic Fractionation (CELF) process. So, electrocatalytic degradation of lignin in this solvent is beneficial because the product from CELF process can be directly used here and thus it can work as a secondary treatment process for CELF process. Cyclic voltammetry (CV) and Chronoamperometry (CA) which are important tools for identifying redox reactions happening in the system is used here. In this presentation, for varying concentrations of Lignin, Tetrahydrofuran and sulfuric acid the results found from CV and CA will be discussed with practical significance.Keywords: Recalcitrant biopolymer, Lignin in organic solvent, controlled electrocatalysis, secondary treatment for CELF process, Cyclic Voltammetry

Utilization of Sago Solid Waste for Bioethanol Production With Variation of Sago Solid Waste-Solvent Ratio and Pre-treatment Time

Sago solid waste is a lignocellulosic material that can be used as a raw material for making bioethanol. The lignin component of lignocellulose can slow saccharification by preventing cellulase enzymes from accessing cellulose. The pre-treatment stage is the first stage of the lignocellulose-to-bioethanol conversion process, and it is used to lower lignin levels in lignocellulose. Saccharification and fermentation are the next processes in turning lignocellulosic material to bioethanol. The pre-treatment stage was carried out in this study using a 10% NaOH solution at a 4 bar pressure reactor and a temperature of 140 °C, while the saccharification and fermentation stages were carried out simultaneously (SSF) using cellulase enzymes and yeast Saccharomyces cerevisiae at 30 °C and pH 5. The ratio of sago solid waste to NaOH solution and the period of the pre-treatment process were varied in the study. The sago solid waste to solvent ratios were 1:5, 1:6, and 1:7, with processing times beginning at 20 minutes, 30 minutes, and 40 minutes. The maximum lignin reduction results (60.11%) were obtained at a ratio of 1:7 and a pre-treatment time of 40 minutes, while the highest yield of sago solid waste mass (35.14%) was obtained at a ratio of 1:5 and a pre-treatment process duration of 20 minutes. The results of the initial treatment stage were then continued with SSF for 0 hours, 24 hours, 48 hours, and 72 hours with the highest bioethanol content of 12% at 72 hours.

Pre-treatment, Physicochemical Properties and Production of Bioethanol from Rice Husk using Fungi Isolated from Waste Dumpsite in Kaduna, Nigeria

This research is based on the pre-treatment and physicochemical characterization of rice husk and production of Bioethanol from rice husk using fungal isolates obtained from waste dump sites in Kaduna Nigeria. Standard procedures were followed. The results revealed a reduction in lignin (from 21.40 to 12.08%), hemicellulose (22.04-18.92%), protein (14.56-8.56%) and ash (1.31-1.04%) contents which resulted to an increase in the cellulosic fraction (49.55-58.29%) of the rice husk.. A significant difference (p<0.05) was observed in the reducing sugar concentrations of the 50g substrate concentration using Aspergillus niger SIF2 (0.60±0.30mg/ml), Aspergillus flavus CMXY22565 (0.56±0.29mg/ml) and a consortium (1.17±0.82mg/ml) of both organisms after 120 hours of enzymatic hydrolysis. The results also revealed a significant yield (p<0.05) in bioethanol production using Pichia kudriavzevii IPBCC.y.161552 (4.91±2.51%), Saccharomyces cerevisiae FJI (5.39±2.87%) and a consortium (9.02±4.83%) of both organisms. There was an increase in temperature and titratable acidity and a decrease in pH and specific gravity. The FTIR revealed a high ethanol content of 68% from the bioethanol produced from the 50g substrate concentration hydrolysed and fermented using a consortium of molds and yeasts. The results therefore suggest that bioethanol can be produced from rice husk with maximum yields obtained using a consortium of Aspergillus niger SIF2 and Aspergillus flavus CMXY22565 for hydrolysis as well as a consortium of Saccharomyces cerevisiae FJI and Pichia kudriavzevii IPBCC.y.161552 for fermentation.

Homoeologous non-reciprocal translocation explains a major QTL for seed lignin content in oilseed rape (Brassica napus L.)

Key messageA homoeologous non-reciprocal translocation was identified in the major QTL for seed lignin content in the low lignin line SGDH14. The lignin biosynthetic gene PAL4 was deleted.Oilseed rape is a major oil crop and a valuable protein source for animal and human nutrition. Lignin is a non-digestible, major component of the seed coat with negative effect on sensory quality, bioavailability and usage of oilseed rape’s protein. Hence, seed lignin reduction is of economic and nutritional importance. In this study, the major QTL for reduced lignin content found on chromosome C05 in the DH population SGDH14 x Express 617 was further examined. SGDH14 had lower seed lignin content than Express 617. Harvested seeds from a F2 population of the same cross were additionally field tested and used for seed quality analysis. The F2 population showed a bimodal distribution for seed lignin content. F2 plants with low lignin content had thinner seed coats compared to high lignin lines. Both groups showed a dark seed colour with a slightly lighter colour in the low lignin group indicating that a low lignin content is not necessarily associated with yellow seed colour. Mapping of genomic long-reads from SGDH14 against the Express 617 genome assembly revealed a homoeologous non-reciprocal translocation (HNRT) in the confidence interval of the major QTL for lignin content. A homologous A05 region is duplicated and replaced the C05 region in SGDH14. As consequence several genes located in the C05 region were lost in SGDH14. Thus, a HNRT was identified in the major QTL region for reduced lignin content in the low lignin line SGDH14. The most promising candidate gene related to lignin biosynthesis on C05, PAL4, was deleted.

A group III patatin-like phospholipase gene pPLAIIIδ regulates lignin biosynthesis and influences the rate of seed germination in Arabidopsis thaliana.

The lignification of plant secondary walls is an important process that provides plants with mechanical support. However, the presence of lignin in the secondary walls affects the readily availability of cellulose required in various industries, including the biofuel, paper, and textile industries. Thus, plants with less lignin are ideal for usage in such industries. Molecular studies have identified genes that regulate plant lignification, including group III plant-specific patatin-related phospholipase genes. Recent studies have reported decreased lignin content when pPLAIIIα, pPLAIIIγ (from Arabidopsis thaliana), and pPLAIIIβ (from Panax ginseng) were overexpressed in Arabidopsis. However, the role played by a closely related gene pPLAIIIδ in lignin biosynthesis has not yet been reported. In this study, we found that overexpression of the pPLAIIIδ significantly reduced the lignin content in secondary cell walls, whereas the silencing of the gene increased secondary walls lignification. Transcript level analysis showed that the key structural and regulatory genes involved in the lignin biosynthesis pathway decreased in overexpression, and increased in plants with silenced pPLAIIIδ. Further analysis revealed that pPLAIIIδ played an influential role in several physiological processes including seed germination, and chlorophyll accumulation. Moreover, the gene also influenced the size of plants and plant organs, including leaves, seeds, and root hairs. Generally, our study provides important insights toward the use of genetic engineering for lignin reduction in plants and provides information about the agronomical and physiological suitability of pPLAIIIδ transgenic plants for utilization in biomass processing industries.

Comparison of acid and alkaline pre-treatment on methane production from empty palm oil fruit bunches (OPEFB): Effect on characteristics, digester performance, and correlation of kinetic parameters

This paper focused on comparing the impact of two different chemical pretreatments on various characteristics of OPEFBs (i.e., physical, structural, and morphological properties), methane production, digestate characteristics, and kinetic modelling. The biochemical methane potential (BMP) test showed that alkaline-treated OPEFBs produced higher methane yields than acid-treated OPEFBs. Accordingly, the methane yields became far higher after NaOH pretreatment, showing 0.186–0.224 m3CH4/kg VSadded compared with 0.102 m3CH4/kg VSadded and 0.093–0.115 m3CH4/kg VSadded from untreated and acid-treated OPEFBs. The best treatment was alkaline pretreatment of P2N3, which gave the highest methane yield increase (by 1.2-fold). The Scanning Electron Microscopy and Energy Dispersive X-ray (SEM-EDX) results of acid-treated OPEFBs indicated disruption of cell wall and loss of some minerals. However, alkaline-treated OPEFBs have more pores due to silica and other chemicals releases (i.e., lignin, hemicellulose, etc.). The kinetic study showed that all models (i.e., modified Gompertz, logistic, and transference) were in good agreement with the experimental data. Both experimental data and models confirmed P2N3 (i.e., NaOH concentrations of 3.8%) as the best results, indicated by the highest lignin reduction and methane production. This study showed an excellent opportunity to digest alkaline-treated OPEFBS, yet more in-depth investigations with sustainability and circular economy perspectives are needed.

Boosting enzymatic hydrolysis of steam-pretreated softwood by laccase and endo-β-mannanase enzymes from Streptomyces ipomoeae CECT 3341

Ligninases and hemicellulases are crucial as accessory enzymes to increase the enzymatic hydrolysis of lignocellulose, boosting sugars production from which biofuels and bioproducts could be obtained. In order to find new sources of these accessory enzymes, this study evaluates the potential of laccase and mannanase enzymes from Streptomyces ipomoeae for improving the conventional hydrolysis with commercial cellulases of steam-pretreated softwood. For that, different laccase treatment and mannanase supplementation strategies were performed. S. ipomoeae laccase increased both glucose and xylose production (17.8% and 9.3%, respectively), which was attributed to a removal of phenols of 29%. Moreover, the combination of laccase and alkaline extraction produced a lignin reduction of 16.2%, improving the glucose and xylose production by almost 41.3% and 44.9%, respectively. On the other hand, the supplementation of S. ipomoeae mannanase to the hydrolysis 24 h before the addition of cellulases increased the glucose (18.4%), xylose (12.3%), and mannose (47.2%) production.

The Mercerization Process and Its Impact on Rice Straw Surface Topography

The present study shows the mercerization process (NaOH) and its effect on the physicochemical characteristics of rice straw. In total, 12 samples were analyzed, 3 as a comparative basis and 9 that were exposed to different concentrations of NaOH (1%, 2%, and 3%) and times, in hours, of exposure in an alkaline environment (1 h, 2 h, and 3 h). The loss of silica and reduction in lignin and hemicellulose contents identified in the chemical characterization allowed for a visualization of the surface topography and cross-section of the treated samples, making it possible to contrast them with the three untreated samples by comparing their roughness, the appearance of their pores, and the contractions of vascular bundles in their conductive tissue. An analysis of the data showed that the results between some treatments were similar, suggesting a reduction in resources in future research. The mechanical resistance allowed for identifying that the NaOH-1%-1 h treatment obtained a better mechanical resistance in the treated samples. However, NaOH-3%-1 h, with the third lowest resistance, obtained the highest % elongation compared to the other samples. These physicochemical changes with NaOH facilitate the selection of the treatment concerning the fiber–matrix interaction and final performance of the composite material that intends to use rice straw as a reinforcing fiber.

Poly(Lactic Acid) Composites with Lignin and Nanolignin Synthesized by In Situ Reactive Processing.

Poly(lactic acid) (PLA) composites with 0.5 wt% lignin or nanolignin were prepared with two different techniques: (a) conventional melt-mixing and (b) in situ Ring Opening Polymerization (ROP) by reactive processing. The ROP process was monitored by measuring the torque. The composites were synthesized rapidly using reactive processing that took under 20 min. When the catalyst amount was doubled, the reaction time was reduced to under 15 min. The dispersion, thermal transitions, mechanical properties, antioxidant activity, and optical properties of the resulting PLA-based composites were evaluated with SEM, DSC, nanoindentation, DPPH assay, and DRS spectroscopy. All reactive processing-prepared composites were characterized by means of SEM, GPC, and NMR to assess their morphology, molecular weight, and free lactide content. The benefits of the size reduction of lignin and the use of in situ ROP by reactive processing were demonstrated, as the reactive processing-produced nanolignin-containing composites had superior crystallization, mechanical, and antioxidant properties. These improvements were attributed to the participation of nanolignin in the ROP of lactide as a macroinitiator, resulting in PLA-grafted nanolignin particles that improved its dispersion.

Moso bamboo expansion into a broadleaved forest alters the dominant soil organic carbon source

AbstractBoth microbes and plants contribute to soil organic carbon (SOC) formation and retention, but their roles in controlling SOC dynamics in forest soils under Moso bamboo (Phyllostachys edulis) expansion remain unclear. Here, amino sugars and lignin monomers were measured to represent microbial necromass and plant‐derived components, respectively. The observed decline in both amino sugars and lignin monomers during Moso bamboo expansion indicates a reduction in microbial necromass and recalcitrant plant contributions to SOC composition. This could be attributed to a limitation of microbial substrates and proliferation caused by the reduced litter inputs resulting from the expansion. The proportion of microbial necromass contributing to the SOC pool increased, but that of lignin monomers decreased, as SOC content decreased with Moso bamboo expansion. This suggests that the decrease of SOC during bamboo expansion was mainly due to the reduction of lignin, while the increased contribution of microbial‐derived carbon to SOC may serve to improve SOC stability. Our study sheds light on the altered SOC source inputs resulting from Moso bamboo expansion and emphasizes the need for sustainable forestry management practices that differentiate between microbial‐ and plant‐derived carbon pools.

Optimization of pretreatment in delignification of hyacinth biomass for ethanol production

Water hyacinth ( Eichhornia crassipes ) is one of the potential feedstocks for bioethanol production due to their higher cellulose content. It needs the optimization of pretreatment to remove lignin and release cellulose and hemicellulose from lignocellulosic complex. Pretreatment was done using sulfuric acid, sodium hydroxide, and calcium hypochlorite as soaking agents. Experiment was carried out at 121 °C for 15 minutes. Pretreatment with 1% sulfuric acid decreased lignin by 6.74%, 4.0% sodium hydroxide reduced lignin content by 11.23%, whereas pretreatment with 0.3% calcium hypochlorite removed lignin by 8.30% from original lignin content lignocellulosic substrate. Therefore, sodium hydroxide pretreatment showed highest efficacy in delignification processes, followed by calcium hypochlorite, and sulfuric acid pretreatments. Keywords: Lignin reduction; Lignocellulose; Pretreatment; Water hyacinth

Quail manure as a supplementary feedstock to corn stover: Conjoint effect of alkaline pretreatment and co-digestion approaches on organics solubilization and methane yield

To overcome low carbon/nitrogen (C/N) ratio, recalcitrant nature, and enhancement methane production of corn stover, it was co-digested with quail manure along with alkaline pretreatment using NaOH. The best-case scenario was attained when a mixture of 50/50 with 2.5% NaOH pretreated corn stover was employed. As compared to control (mono-digested/untreated corn stover), largest lignin reduction (16%), organics solubiliztion (27.7%), maximum methane yield enhancement (2-fold higher, 296.5 mL CH4 gVSadd−1) was achieved. The most important contributing factor to enhancement was the synergistic effect resulting from ideal C/N ratio applied and hydrolysis rate accelerating. The experimental data obtained were validated using first-order kinetic model. Energy analysis revealed a positive energy balance, with a 6-fold increase in energy output. These results highlight the feasibility of recycling available agricultural wastes into renewable resources rather than just discarding them, with the added benefits of producing clean biogas without the need for expensive high-tech equipment.

Effect of processing temperature on nanolignin quality during ultrafine friction grinding

Nanoparticles are a new frontier to valorize underutilized and abundant lignin generated by biorefineries. Typical chemical processes to synthesize lignin micro- and nano-particles (LMNPs) use large quantity of organic solvents and therefore, could adversely impact the environment. Hence, we have employed an eco-friendly mechanical approach, i.e., ultrafine friction grinding (UFG), to produce “green” LMNPs with controlled size and micromorphology. Specifically, we investigated the effect of processing temperature, at 0, 25 and 70 °C, on lignin nanosizing. Our results showed that low temperature (0 °C) significantly favored the size reduction of lignin where we achieved a median particle size of ∼100 nm after 12 grinding passes. At 70 °C, LMNPs reached a size equilibrium of ∼160 nm within four passes but did not decrease in size upon subsequent grinding. Moreover, analysis of the LMNPs by SEM showed that samples produced at 0 °C mostly had irregular flat shapes with sharp angles, such as stars and polyhedrons, with a glabrous surface, whereas, samples produced at 25 and 70 °C featured spheres and rods with nanoscopic pores on the surface. Physico-chemical properties of LMNPs, such as molecular weight and thermal degradation, did not change significantly compared to the original lignin, however, samples generated at 0 °C exhibited significantly fewer inter-unit linkages than those generated at 70 °C. Our study thus shows that varying the grinding temperature facilitates the customization of LMNP micromorphology. Furthermore, the proposed method for LMNP manufacturing is simple and eco-friendly, and presents a viable approach for lignin valorization.