Transformation Of Lignocellulosic Biomass Research Articles

Isolation and Molecular Screening of Fungus as Agents in Cellulolytic Transformation Materials from Symbiotic Lichen

The abundance of lignocellulosic waste makes it a potential source for advanced biomaterials through various transformation processes. Lignocellulosic biomass transformation to advanced biomaterials involves enzymes from extracellular metabolites of microorganisms capable of hydrolyzing lignocellulose. This research was to molecularly screen fungi found in symbiotes of lichen endemic to trees growing in North Minahasa (North Sulawesi) with lignocellulolytic transformation enzymes. Molecular screening was conducted from identified fungi isolates based on partial genetical analysis on the locus of Internal Transcribed Spacer (ITS) of the fungi’s ribosomal DNA. Fungi isolates screening identified Trichoderma koningiopsis (isolate HZA8 and isolate HZA6), Penicillium sumatraense (strain CBS 127365 and strain CBS 130380), Trichoderma hamatum (isolate PAN12-45 and isolate PAN12-05), Aspergillus aculeatus (strain A1.9 18S), Aspergillus aculeatus (isolate XSD-74), Trichoderma reesei (strain S2606 and isolate 5A14). Molecular identification and BLAST homology of potentially lignocellulolytic fungi isolates rDNA indicated that isolate KB2 had close relationship with Trichoderma reesei at 100% degree of closeness and an index of cellulolytic activity of 1.19. While isolate KB3 appeared closely related to Aspergillus aculeatus at 99.83% degree of closeness and an index of cellulolytic activity of 1.57. Therefore, the potential of developing bioprocess industries in general and in particular is most probable.

Microwaves and Ultrasound as Emerging Techniques for Lignocellulosic Materials

Currently, in the context of biorefinery and bioeconomy, lignocellulosic biomass is increasingly used to produce biofuels, biochemicals and other value-added products. Microwaves and ultrasound are emerging techniques that enable efficient and environmentally sustainable routes in the transformation of lignocellulosic biomass. This review presents some of the most important works published in the last few years on the application of microwaves and/or ultrasound in lignocellulosic materials pretreatment and can be used as a starting point for research into this theme. This review is divided into four parts. In Part I, the theoretical fundamentals of microwave and ultrasound treatments are reviewed. Dielectric constants for biomass, factors that influence pretreatment, are some of the subjects addressed. In Part II, the effects that these techniques have on lignocellulosic biomass (on the size and surface area of the particle; on the content of lignin, hemicellulose and cellulose; on the crystallinity index of cellulose; on the effect of solubilization of organic matter; on hydrolysis and reduction of sugars) are discussed. In Part III, emphasis is given to the contribution of microwaves and ultrasound in obtaining value-added products. In this context, several examples of liquefaction and extraction procedures are presented. Part IV describes examples of performing sonocatalysis on lignocellulosic biomass to obtain value-added products, such as furfural, whose production is significantly reduced by ultrasound treatment.

Current Status and Challenges for Metal-Organic-Framework-Assisted Conversion of Biomass into Value-Added Chemicals.

Owing to the abundance of availability, low cost, and environmental-friendliness, biomass waste could serve as a prospective renewable source for value-added chemicals. Nevertheless, biomass conversion into chemicals is quite challenging due to the heterogeneous nature of biomass waste. Biomass-derived chemicals are appealing sustainable solutions that can reduce the dependency on existing petroleum-based production. Metal-organic frameworks (MOFs)-based catalysts and their composite materials have attracted considerable amounts of interest in biomass conversion applications recently because of their interesting physical and chemical characteristics. Due to their tunability, the catalytic activity and selectivity of MOF-based catalyst/composite materials can be tailored by functionalizing them with a variety of functional groups to enhance biomass conversion efficiency. This review focuses on the catalytic transformation of lignocellulosic biomass into value-added chemicals by employing MOF-based catalyst/composite materials. The main focus is given to the production of the platform chemicals HMF and Furfural from the corresponding (hemi)cellulosic biomass, due to their versatility as intermediates for the production of various biobased chemicals and fuels. The effects of different experimental parameters on the conversion of biomass by MOF-based catalysts are also included. Finally, current challenges and perspectives of biomass conversion into chemicals by MOF-based catalysts are highlighted.

Effective conversion of corn stalk into ethyl levulinate and crude lignin catalyzed by ionic liquids

The chemical transformation of lignocellulosic biomass into platform chemicals is one of the most efficient utilization methods for agricultural wastes. In this work, a one-pot strategy for the conversion of corn stalk to ethyl levulinate and further extraction of valorizable lignin catalyzed by ILs was proposed. With the optimized catalyst of [C3H6SO3Hmim]HSO4, corn stalk of 92.45% was transformed into ethyl levulinate with a favorable yield of 24.72% at 200 °C for 90 min. Furthermore, the lignin extraction was substantially influenced by co-solution system. A high lignin yield of 79.94% was achieved with ethanol content of 75% (v/v) in the ethanol-water system. The analysis on morphology, thermal stability and functional group showed that condensation of lignin occurred during the liquefaction process, the two-dimensional heteronuclear single quantum correlation (2D-HSQC) investigation demonstrated that the stable structure of lignin provides a favorable foundation for its valorization. Overall, this work proposed a feasible biorefinery strategy for effective conversion and utilization of lignocellulosic biomass.

Mild Dealumination of H-ZSM-5 Zeolite for Enhanced Conversion of Glucose into 5-Hydroxymethylfurfural in a Biphasic Solvent System

Transformation of lignocellulosic biomass into high-value chemicals is a viable strategy for sustainable development of a bio-based economy. 5-Hydroxymethylfurfural (HMF) is one of potential platform bio-chemicals for the manufacture of various renewable products. In this work, a commercial H-ZSM-5 zeolite was used as a starting material for preparing a series of acid catalysts with bifunctionality for direct dehydration of glucose to HMF in a biphasic water/tetrahydrofuran system. The pristine H-ZSM-5 was mildly dealuminated by refluxing with dilute nitric acid solutions to adjust its acid properties. Although the acid treatment slightly altered the elemental composition, textural properties, and morphology of zeolite, the total acidity and distribution of acid sites were significantly modified. Some non-framework aluminum (Al) oxide clusters were removed from the parent H-ZSM-5 simultaneously with a partial hydrolysis of zeolitic framework. An increased fraction of coordinatively unsaturated framework Al species enhanced the number of Lewis acid sites. Using 0.1 M solution in the treatment provided the suitable catalyst (0.1DeAl.H-ZSM-5), giving a glucose conversion and HMF yield of >99% and 64.7%, respectively, and a good reusability under the optimized reaction conditions. These results show the industrial potential of the proposed method for simple but efficient preparation of H-ZSM-5 catalysts for producing HMF via the catalytic dehydration of glucose.

Applications of ionic liquids for the biochemical transformation of lignocellulosic biomass into biofuels and biochemicals: A critical review

Lignocellulosic materials are valuable resources in today's bioprocess technologies; however, their recalcitrance is a major barrier in industry regarding their conversion to microbial products. For this purpose, in this study, the synthesis of ionic liquids (ILs), its function in the hydrolysis of lignocellulosic materials, its biochemistry and possible toxic effects were investigated. In addition, the bioconversion of lignocellulosic materials pretreated with ionic liquids to biofuels (bioethanol, biobutanol, biogas and hydrogen) and various biochemicals is discussed in detail. For this, the focus is on the potential of ILs for industrial integration and use in large-scale reactors. ILs offer significant advantages due to their potential for ease of use and their features such as recovery and reuse after pretreatment. However, there are economic and technical problems that need to be solved to expand ILs in industrial systems and increase their use potential. To overcome these problems and the usability of ILs technologies in industry, techno-economic analyses has been examined and compared with traditional processes.

Bifunctional zirconium-based metal-organic frameworks as chemoselective catalysts for the synthesis of γ-valerolactone from furfural via a one-pot cascade reaction

The transformation of lignocellulosic biomass to platform compounds (γ-valerolactone, GVL) was a significant component in biomass development. Herein, sulfonated Zr-based metal-organic frameworks (MOF-808), a bifunctional heterogeneous catalyst with Lewis and Bronsted acid sites, were prepared to catalyze the one-pot cascade reaction of furfural (FUR) to GVL. The successful modification of the sulfonic group on MOF-808 was substantiated by multiple characterization methods. By adjusting the sulfuric acid concentration to balance the Lewis acid and Bronsted acid sites of the catalyst, S-808–2.37 was confirmed as the preferred catalyst and a 60.4 % GVL yield was achieved with 99.1 % carbon balance under the optimal conditions. Moreover, the 72.8 % GVL yield reached in the 40x magnification experiment also boded well for the catalyst’s application potential. The work in this paper opened up new perspectives for the application of MOF-808 porous materials in the field of selective catalytic conversion of biomass involving multi-step reactions.

Catalytic Transfer Hydrogenation of Lignocellulosic Biomass Model Compounds Furfural and Vanillin with Ethanol by an Air‐stable Iron(II) Complex

AbstractThe chemical transformation of lignocellulosic biomass into various fine chemicals is the necessity for sustainable developments. A significant research interest has been devoted to develop catalysts for the reduction of cellulose and lignin model compounds furfural and vanillin, respectively. An iron(II) complex (1) was readily synthesized by facile coordination of NNO pincer ligand with FeCl2.4H2O. The air‐stable complex 1 was efficiently utilized for the catalytic transfer hydrogenation of furfural and vanillin using ecologically benign but challenging primary alcohol ethanol. Secondary alcohol isopropanol was also utilized. Various other biomass model compounds and structurally related aldehydes were also effectively reduced. Kinetic studies suggested first order kinetics in catalyst and zeroth order in substrate. Based on the experimental evidences and published reports, a catalytic cycle is proposed which proceed via iron(II)‐dialkoxides and alkoxide‐hydride intermediates. Finally, CHEM21 green metrics toolkit was utilized to evaluate the sustainable and green credentials of the catalytic protocols.

Optimization of Different Acid-Catalyzed Pretreatments on Co-Production of Xylooligosaccharides and Glucose from Sorghum Stalk.

There is an increasing emphasis on the transformation of lignocellulosic biomass into versatile products. The feasibility of preparing xylooligosaccharides (XOS) by hydrolysis of sorghum stalk (SS) using organic and inorganic acids was studied. The influences of different acids (gluconic acid, acetic acid, sulfuric acid, and oxalic acid), process time and temperature on the hydrolysis of SS were explored. The findings indicated XOS yield can be maintained at a high level under different conditions with organic acid pretreatments. Optimum yield of XOS (39.4%) was obtained using sulfuric acid (pH 2.2) at 170 °C and 75 min of process time. It is suggested when reaction temperature and time were increased, both X5 and X6 are cracked into XOS with lower molecular mass such as X2, X3, and X4. Moreover, the results based on mass balance showed that up to 110 g (XOS) plus 117 g (glucose) can be recovered from 1000 g of SS. Results will give insights into establishing an efficient acid pretreatment of sorghum stalk to coproduction of XOS and glucose.

High efficiency and clean separation of eucalyptus components by glycolic acid pretreatment

Glycolic acid has chemical properties similar to those of formic acid. Therefore, similar to formic acid pretreatment, glycolic acid pretreatment has the separation effect of hemicellulose. In this study, eucalyptus hemicellulose was effectively separated by glycolic acid pretreatment. The effects of glycolic acid concentration, temperature and time on the separation of cellulose, hemicellulose and lignin were investigated. The optimum conditions were acid concentration 5.40%, temperature 140 °C, time 3.0 h. The highest yield of xylose was 56.72%. The recovery rate of glycolic acid was 91%. Compared to formic acid, the yield of xylose increased to 10.33% while that of lignin decreased to 11.08%. It showed high selectivity for hemicellulose separation, yielding 65.48% hemicellulose with 72.08% purity. The depolymerization and repolymerization of lignin were inhibited. The integrity of the cellulose structure was preserved. It provides theoretical support for the fractional separation and high-value transformation of lignocellulosic biomass.

Lignocellulose biomass bioconversion during composting: Mechanism of action of lignocellulase, pretreatment methods and future perspectives

Composting is a biodegradation and transformation process that converts lignocellulosic biomass into value-added products, such as humic substances (HSs). However, the recalcitrant nature of lignocellulose hinders the utilization of cellulose and hemicellulose, decreasing the bioconversion efficiency of lignocellulose. Pretreatment is an essential step to disrupt the structure of lignocellulosic biomass. Many pretreatment methods for composting may cause microbial inactivation and death. Thus, the pretreatment methods suitable for composting can promote the degradation and transformation of lignocellulosic biomass. Therefore, this review summarizes the pretreatment methods suitable for composting. Microbial consortium pretreatment, Fenton pretreatment and surfactant-assisted pretreatment for composting may improve the bioconversion process. Microbial consortium pretreatment is a cost-effective pretreatment method to enhance HSs yields during composting. On the other hand, the efficiency of enzyme production during composting is very important for the degradation of lignocellulose, whose action mechanism is unknown. Therefore, this review describes the mechanism of action of lignocellulase, the predominant microbes producing lignocellulase and their related genes. Finally, optimizing pretreatment conditions and increasing enzymatic hydrolysis to improve the quality of composts by controlling suitable microenvironmental factors and core target microbial activities as a research focus in the bioconversion of lignocellulose during composting in the future.

Valorization of agricultural residues: Different biorefinery routes

Agricultural residues are naturally available lignocellulosic biomass having high content of carbon. These residues should imminently be discarded to prevent pollution or can be harnessed for the production of bioenergy and bio-based products. This paper reviews the various types of agricultural residues such as rice straw, wheat straw, maize straw etc and their utilization for the generation of high valuable products. Basic components of agricultural residues which act as a feedstock for bioenergy production and also different biorefineries of agricultural residues based on cellulose, hemicellulose, and lignin for the transformation of lignocellulosic biomass into valuable products are discussed. Economic analysis performs a major role in technical advancement to ensure economic viability for the valorization of agricultural residues. This paper casts insight into the techno-economic analysis and the life-cycle assessment, the most pertinent approach to assess the environmental consequences of the developed products. To conclude, a discussion and suggestion for future studies is presented.

Influence of delignification and reaction conditions in the aqueous phase transformation of lignocellulosic biomass to platform molecules

The effect of oxidative and reductive delignification processes on the hydrolysis of pine sawdust at mild conditions (200–1000 ppm of HCl and 140–220 °C) is studied in this work. Dimers and reduced sugars are the main products obtained with the fresh sawdust (>82%), reaching a maximum liquid phase yield of 17% after 8 h, at the strongest conditions. This conversion increases up to almost 40% with the pretreated sawdust, obtaining selectivities higher than 87% of levulinic acid and a well-defined distribution of the relevant platform molecules (sugars, HMF, furfural, levulinic acid) as function of the severity of the reaction, decreasing the humins formation and being possible to define different conditions to maximize each yield. These conclusions were corroborated by the kinetic analysis, obtaining a clear decrease in the energy activation for all the individual steps involved in this process.

Computer-Aided Environmental Assessment Applied for Estimation of Ecological Impacts Derived from Topological Pathways Based on Lignocellulosic Biomass Transformation

The growing awareness to include sustainability goals in the chemical process design has been making palpable since many governments and research institutions have made many efforts precisely to progress new ways to transform available resources into valuable chemicals. In this sense, this work is presenting a computer-aided evaluation based on environmental impact assessment and comparison of technical parameters for estimating the potential effects of two biorefinery designs. The first process involved a multiproduct production of acetone, butanol, and ethanol from cassava waste, while the second biorefinery comprised of succinic acid and bioethanol production from a mixture of cassava waste and banana rachis. These residues are highly available in the North Colombia region due to the agroindustrial activities of that zone. The developed environmental analysis employed the waste reduction algorithm (WAR) for estimating impact generation and output rates considering atmospheric and toxicological categories. Otherwise, process simulation of biorefineries showed production of 546.3 kg/h of acetone, 280.0 kg/h of ethanol, and 1305 kg/h of butanol for topology 1, while topology 2 delivered a synthesis of 13,865.7 kg/h of acetic acid and 2277.9 kg/h of ethanol. Data generated from process simulation allowed performing a technical comparison between evaluated biorefineries, showing a higher performance of evaluated indicators for topology 2. These evaluated variables included resource energy efficiency, and production yield, among others. The environmental analysis provided relevant information, indicating that topology 2 is a better alternative from an ecological viewpoint since this design would emit substances with lower effects than topology 1.

Chemo-Catalytic Transformation of Cellulose and Cellulosic-Derived Waste Materials into Platform Chemicals

The transformation of lignocellulosic biomass and residues to valuable products is an important area of modern biotechnology. The residues can include industrial and municipal wastes, agricultural residues, forest residues and natural herbaceous plants. They are mostly composed of cellulose, hemicellulose, and lignin. Cellulose being the most abundant biopolymer on earth, it has been identified as an alternative to petroleum-based feedstock to produce platform chemicals. However, the use of cellulose is challenging due to its recalcitrance to dissolution. At present, the catalytic conversion of cellulose and cellulosic materials is studied by various research groups. This review outlines the procedures for the chemo-catalytic conversion of cellulose to help valorize paper wastes into platform chemicals. These platform chemicals include sorbitol, ethylene glycol, gluconic acid, lactic acid, levulinic acid, and hydroxymethylfurfural, among others. The recent advances on the design and the use of novel homogenous and heterogenous catalysts have been reported. Special attention has been given to heterogenous catalysts due to their green status and scale-up potential. Moreover, the potential to recycle and reuse pulp and paper for bioprocessing has also been reviewed. Finally, the current and future market scenarios for these platform chemicals have been discussed. If economically competitive, these building block chemicals could overtake their fossil-based counterparts.

Eco-friendly Transformation of Waste Biomass to Biofuels

Background: The development of viable alternative fuel sources is assuming a new urgency in the face of climate change and environmental degradation linked to the escalating consumption of fossil fuels. Lignocellulosic biomass is composed primarily of high-energy structural components such as cellulose, hemicellulose and lignin. The transformation of lignocellulosic biomass to biofuels requires the application of both pretreatment and conversion technologies. Methods: Several pretreatment technologies (e.g. physical, chemical and biological) are used to recover cellulose, hemicellulose and lignin from biomass and begin the transformation into biofuels. This paper reviews the thermochemical (e.g. pyrolysis, gasification and liquefaction), hydrothermal (e.g. subcritical and supercritical water gasification and hydrothermal liquefaction), and biological (e.g. fermentation) conversion pathways that are used to further transform biomass feedstocks into fuel products. Results: Through several thermochemical and biological conversion technologies, lignocellulosic biomass and other organic residues can produce biofuels such as bio-oils, biochar, syngas, biohydrogen, bioethanol and biobutanol, all of which have the potential to replace hydrocarbon-based fossil fuels. Conclusions: This review paper describes the conversion technologies used in the transformation of biomass into viable biofuels. Biofuels produced from lignocellulosic biomass and organic wastes are a promising potential clean energy source with the potential to be carbon-neutral or even carbonnegative.

Novel Routes in Transformation of Lignocellulosic Biomass to Furan Platform Chemicals: From Pretreatment to Enzyme Catalysis

The constant depletion of fossil fuels along with the increasing need for novel materials, necessitate the development of alternative routes for polymer synthesis. Lignocellulosic biomass, the most abundant carbon source on the planet, can serve as a renewable starting material for the design of environmentally-friendly processes for the synthesis of polyesters, polyamides and other polymers with significant value. The present review provides an overview of the main processes that have been reported throughout the literature for the production of bio-based monomers from lignocellulose, focusing on physicochemical procedures and biocatalysis. An extensive description of all different stages for the production of furans is presented, starting from physicochemical pretreatment of biomass and biocatalytic decomposition to monomeric sugars, coupled with isomerization by enzymes prior to chemical dehydration by acid Lewis catalysts. A summary of all biotransformations of furans carried out by enzymes is also described, focusing on galactose, glyoxal and aryl-alcohol oxidases, monooxygenases and transaminases for the production of oxidized derivatives and amines. The increased interest in these products in polymer chemistry can lead to a redirection of biomass valorization from second generation biofuels to chemical synthesis, by creating novel pathways to produce bio-based polymers.

One-step transformation of biomass to fuel precursors using a bi-functional combination of Pd/C and water tolerant Lewis acid

Direct one-pot transformation of lignocellulosic biomass has been developed as an effective and sustainable strategy to produce fuel blend stocks and high value chemical building blocks. In this wok, a bi-functional catalyst system consisting of palladium supported on carbon (Pd/C) and metal triflates (i.e., Sm(OTf)3, La(OTf)3, and Cu(OTf)2) were shown to promote the biomass liquefaction in both hot-compressed water and supercritical ethanol medium, converting fir wood into oxygenated compounds. The highest bio-oil yield from hydrothermal liquefaction (HTL) was 10.47 wt% over Pd/C whereas the highest bio-oil yield of 49.71 wt% was achieved from supercritical ethanol liquefaction (SCEL) over the bi-functional catalyst system of Pd/C and La(OTf)3. Higher heating values, carbon recovered values and boiling point distributions were further determined for elucidating the physical properties of the bio-oils. Gas chromatography mass spectrometry (GC–MS) analysis of the bio-oils revealed the chemical composition of the bio-oils. Substituted phenols and cyclopentenone/cyclopentanone type compounds consisted of more than 60 area% of the total products from HTL, whereas phenol and esters represented the major products from SCEL. The major reaction pathways are proposed based on the GC–MS results, which include depolymerizaton, isomerization, dehydration, condensation, and hydrogenation.

Recent trends in hyperthermophilic enzymes production and future perspectives for biofuel industry: A critical review

Among different industrial applications of lignocellulosic biomass, biofuel production is receiving increasing attention. Many factors influence the transformation of lignocellulosic biomass into biofuels such as biomass composition, moisture content, and the desired final energy product. However, the presence of lignin and the need for de-polymerization of cellulose and hemicellulose into reducing sugars play a crucial role in the efficiency of biomass conversion. Among different methods, conversion of lignocellulosic biomass to fermentable sugars by enzymatic hydrolysis offers the potential for higher yield, lower energy consumption, higher selectivity and eco-friendly process. In that regard, the stability of hyperthermophilic enzymes at extreme temperatures acquired them a unique potential for the conversion of lignocellulosic biomass. In recent years, many trials were done to enhance the biological production and stability of thermostable enzymes. In addition to optimization of growth conditions and using chemical methods, many new genetic systems were developed. However, there is a gap in literature concerning the novel techniques used to enhance the production of hyperthermophilic enzymes and sustainability in biofuel industrialization. Therefore, the present review aimed to shed light on the recent trends used to enhance the production and stability of hyperthermophilic enzymes focusing on genetic engineering as an efficient and promising technique for cost-effective production. In addition, the impact of hyperthermophilic enzymes on biomass refinery and future biofuel industry was discussed. The present article highlighted the future positive impacts of hyperthermophilic enzymes on the biofuel production and the need of more research in this fascinating and boundless field.

One-pot transformation of lignocellulosic biomass into crude bio-oil with metal chlorides via hydrothermal and supercritical ethanol processing

Grape seeds were deconstructed in both hydrothermal and supercritical ethanol media with a combination of two metal chlorides (TiCl4:MgCl2) to produce bio-oils. The use of metal chloride additives in supercritical ethanol achieved the highest bio-oil yield of 49.2 wt% (300 °C, 30 min). Both the hydrothermal and supercritical ethanol deconstruction with the additives (TiCl4:MgCl2 = 4 mmol:4mmol) produced the bio-oils with a higher heating value (HHV) of 35 MJ/Kg. Gas chromatography-mass spectrometry (GC-MS) analysis of the bio-oils showed that the major products in bio-oils from the hydrothermal deconstruction were acids while the majority products in bio-oils form the supercritical ethanol deconstruction were esters. Nuclear magnetic resonance (NMR) data of the bio-oils suggested that both hydrothermal and supercritical ethanol deconstruction with metal chlorides significantly reduced the non-condensed OH and oxygenated lignin sub-units in bio-oils; while only supercritical ethanol deconstruction with metal chlorides reduced the aliphatic OH and O-alkylated structures in bio-oils.