Lignocellulosic Constituents Research Articles

Extraction of lignocellulosic constituents from cow dung: preparation and characterisation of nanocellulose

Continuous growth of the livestock population over the years has led to the generation of huge livestock waste. Inadequate management of animal waste and its poor disposal poses a serious public health issue and also leads to environmental pollution. In the recent decade, the rational use of lignocellulosic biomass towards preparation of bioproducts such as biofuels and biotextile has come up as a promising alternative for the efficient utilisation of animal waste biomass. Hence, the current study is focused on the efficient utilisation of an abundant source of lignocellulosic constituents, i.e. cow dung by the extraction and estimation of cellulose, lignin, and hemicellulose, respectively by an optimised kraft pulping method. The extracted cellulose was evaluated for the degree of polymerisation and was further used for the preparation of nanocellulose which has a wide range of applications. Cellulose and nanocellulose so obtained were morphologically and spectroscopically characterised by SEM-EDX, CHNS elemental analysis, TEM, and FT-IR techniques. Further, nanocellulose was also evaluated for its physical properties such as crystallinity index and zeta potential, which revealed their good crystallinity and excellent particle stability profile. Hence, this study is an innovative approach towards the valorisation of cow dung waste biomass into useful biomaterial, i.e. nanocellulose.

The contribution of lignocellulosic constituents to Cr(VI) reduction capacity of biochar-supported zerovalent iron

Biochars (BCs) derived from individual and blending lignocellulosic constituents were prepared to harbor zerovalent iron (ZVI/BC) in an effort to discriminate significance of each constituent or combination in ZVI/BC for Cr(VI) removal. BCs and ZVI/BC were characterized by TGA/GSC, XRD, Raman and BET analyses. Cellulose (BCC) and hemicellulose (BCH)-derived BCs has greater C content, H/C ratio, surface area and mass loss than BCs derived from lignin or lignin-containing biopolymer blends (BCLX). As per sorption and XPS analysis, ZVI/BC demonstrated greater Cr(VI) removal capacity than respective BCs, in which reduction accounted for over 77% Cr(VI) detoxification. Cr(VI) reduction by ZVI harbored by BCC and BCH was 19.72–16.54 g kg−1, compared to 5.97–4.26 g kg−1 for BCLX. ZVI/BC prepared by three-biopolymer blends with (12.63 g kg−1) or without (12.32 g kg−1) mineral approximated pinewood-BC (BCP) (13.02 g kg−1) for Cr(VI) reduction, suggesting minerals are not important constituent. Tafel analysis showed BCC and BCH, with lower ID/IG ratio owing to greater graphitization, were more conducible to transfer electron of ZVI in Cr(VI) reduction than BCLX. Thus, cellulose, hemicellulose and lignin can offer a good prediction of property of natural biomass, in which BCC and BCH favor electron transfer of ZVI but BCL is not electroactive.

Characterization of coffee parchment and innovative steam explosion treatment to obtain microfibrillated cellulose as potential composite reinforcement

Most by-product wastes of the coffee industry are underutilized, including a fibrous husk that covers the coffee seeds, known as parchment. The present work aims to characterize the parchment fiber and to study the influence of alkaline treatment followed by a steam explosion process assisted by mechanical high shearing to obtain microfibrillated cellulose. The first step of this study was to quantify, using a three-steps methodology, the lignocellulosic constituents present in the parchment. Cellulose, hemicellulose and lignin were identified by Fourier transform infrared spectrophotometry (FTIR) and thermogravimetric analysis (TGA). From these results it was quantified around 22% of cellulose in the parchment. In sequence, alkaline treatment and steam explosion were performed to raise the cellulose content. The novelty of this work was to perform the steam explosion under relatively milder conditions, in order to produce microfibrillated cellulose with a high aspect ratio. It was observed by TGA an improvement in thermal stability and by X-ray diffraction (XRD) an increasing in the crystallinity. Finally, from scanning electron microscopy (SEM) it was verified that cellulose fibrils became more exposed, with diameters reaching micro and nanometric sizes. This ensures a potential for composite reinforcement with microfibrillated cellulose.

Functional Materials from Paper Wastes: I. From Waste Newsprint Paper and Cardboard to High-Grade Cellulose Fibers

Utilization of paper wastes as renewable resource of lignocellulosic constituents has the opportunity to promote a cleaner environment and to prepare valuable materials. This paper describes our study on an isolation of low-fiber powder cellulose from two grades of wastes as feedstocks: waste newsprint paper and cardboard wrapper through recycling including a thermal defibration, an alkali treatment with a solution of NaOH with a concentration from 0.03 to 1.00 М, bleaching with a solution of Н2О2 with a concentration from 0.8 to 2.6 М followed with an acid hydrolysis of the pretreated species with a solution of HNO3 of 1.5 and 3.0 M. The impact of the pretreatment on sizes of fibers was evaluated with stereoscopic microscopy. The powder celluloses obtained as a result of the acid hydrolysis exhibited the structure of cellulose I revealed with a WAXS method and were of a high-grade purity, according to EDXA. Sorption capacities of the powder celluloses from the waste cardboard and newsprint towards a dye methylene blue were 6.67 and 8.75 mg g–1, respectively.

Investigation on the interactions among lignocellulosic constituents and minerals of biomass and their influences on co-firing

The influences of biomass constituents, such as lignocellulosic components and minerals, on the combustion of coal/biomass blends are of significant importance in co-firing due to its potential impacts on ignition, flame stability and burnout. In this research, combustion characteristics of pure lignocellulosic elements, Rosewood, Mengxi coal and their blends were studied in detail. The effect of minerals in Rosewood on combustion of biomass/Mengxi coal blends was investigated which revealed reductions in the ignition (≤20 °C), peak (≤12 °C) and burnout temperatures (≤6 °C). The results also demonstrate the existence of interactions between lignocellulosic constituents in the model biomass, which is dominated by the interactions of cellulose-derived products with xylan and lignin respectively which led to ∼8% reduction in char oxidation temperature. The minerals in biomass showed different impacts at different stages of the combustion process, such as inhibition effect during the devolatilization stage, and promotive synergy (mainly due to calcium) on ignition and char oxidation.

Thermal and biodegradation properties of poly(lactic acid)/rice straw composites: effects of modified pulping products

In this work, rice straw (RS) as an abundant biomass was chemically thermoplasticized through alkali pulping and benzylation reactions, which destroy inter- and intra-molecular hydrogen bonding of the lignocellulosic constituents and dissociate the cellulosic component of RS from lignin. Two different products of RS benzylation process including benzylated pulp (BP) and pulping liquor (BL) rich in cellulose, with the former, and lignin, with the latter, were incorporated into poly(lactic acid) (PLA) using a twin-screw extruder. By substituting the hydroxyl groups of the lignocellulosic constituents with non-polar benzyl groups, the filler/PLA interfacial adhesion was improved considerably in which no evidence of debonding was observed on cryofractured surfaces of the PLA/BL composites. Indoor soil biodegradation test was performed on samples for 128 days and their weight loss, water uptake, visual observations and crystallization were investigated. While PLA sheets showed negligible deterioration and roughly kept their whole weight, the PLA biocomposites demonstrated considerable degradation after soil burial test due to the higher water absorption, lower glass transition temperature and larger biodegradation rate of fillers. The modified pulping products of RS showed a higher thermal stability than their thermoset-like predecessors. The non-isothermal DSC results demonstrated that the addition of BP and BL particles to PLA reduced the glass transition and melting temperatures of the matrix and resulted in higher degree of crystallinity. The findings showed that RS pulping and benzylation reactions successfully led to more effective fillers for PLA than rice straw.

FUNCTIONAL MATERIALS FROM PAPER WASTES. I. FROM WASTE NEWSPRINT PAPER AND CARDBOARD TO HIGH-GRADE CELLULOSE FIBERS

Utilization of paper wastes as renewable resource of lignocellulosic constituents has the opportunity to promote a cleaner environment and to prepare valuable materials. This paper describes our study on an isolation of low-fiber powder cellulose from two grades of wastes as feedstocks: waste newsprint paper and cardboard wrapper through recycling including a thermal defibration, an alkali treatment with a solution of NaOH with a concentration from 0.03 to 1.00 М, a bleaching with a solution of Н2О2 with a concentration from 0.8 to 2.6 М followed with an acid hydrolysis of the pretreated species with a solution of HNO3 of 1.5 and 3.0 M. An impact of the pretreatment on sizes of fibers was evaluated with a stereoscopic microscopy. The powder celluloses obtained as a result of the acid hydrolysis exhibited the structure of cellulose I revealed with a WAXS method and were of a high-grade purity, according to EDXA. Sorption capacities of the powder celluloses from the waste cardboard and newsprint towards a dye methylene blue were 6.67 mg∙g-1 and 8.75 mg∙g-1 correspondingly.

Stoichiometry and kinetics of single and mixed substrate uptake in Aspergillus niger

In its natural environment, the filamentous fungus Aspergillus niger grows on decaying fruits and plant material, thereby enzymatically degrading the lignocellulosic constituents (lignin, cellulose, hemicellulose, and pectin) into a mixture of mono- and oligosaccharides. To investigate the kinetics and stoichiometry of growth of this fungus on lignocellulosic sugars, we carried out batch cultivations on six representative monosaccharides (glucose, xylose, mannose, rhamnose, arabinose, and galacturonic acid) and a mixture of these. Growth on these substrates was characterized in terms of biomass yields, oxygen/biomass ratios, and specific conversion rates. Interestingly, in combination, some of the carbon sources were consumed simultaneously and some sequentially. With a previously developed protocol, a sequential chemostat cultivation experiment was performed on a feed mixture of the six substrates. We found that the uptake of glucose, xylose, and mannose could be described with a Michaelis–Menten-type kinetics; however, these carbon sources seem to be competing for the same transport systems, while the uptake of arabinose, galacturonic acid, and rhamnose appeared to be repressed by the presence of other substrates.

Sequential organosolv fractionation/hydrolysis of sugarcane bagasse: The coupling use of heterogeneous H3PO4-activated carbon as acid promoter and hydrolysis catalyst

Separation of lignocellulose constituents and hydrolysis of the polysaccharides fraction to sugars are pre-requites in production of biofuels and chemicals. In this study, a sequential organosolv fractionation of sugarcane bagasse and saccharification of the cellulose-enriched pulp in hot compressed water using a coupled heterogenous acid promoter/catalyst was studied. Among the liquid and solid acids tested, H3PO4-Activated carbon showed a high performance on promoting selectivity and yield in fractionation related to its high BET surface area and acid site density. Fractionation in a ternary mixture of methyl isolbutylketone:methanol:water (16:68:16) at 180 °C for 60 min using 5%w/w H3PO4-Activated carbon resulted in 88.9% recovery of cellulose enriched in the solid, together with 84.6% recovery of the hemicellulose as pentoses in the aqueous-alcohol fraction and 76.0% lignin in the organic phase. With no separation of the solid acid, the cellulose fraction could be further hydrolyzed under hot compressed water conditions at 225 °C for 10 min, resulting in the maximal hexose yield of 58.3% from the starting material. The catalyst retained >80% activity after reusing in five consecutive batch cycles. The work demonstrates an efficient integrated fractionation/hydrolysis process with coupling use of the acid promoter/catalyst, with advantages on its high activity, selectivity and reusability.

Non-catalytic Hydrothermal Liquefaction of Biomass: An Experimental Design Approach

Abstract A face centered central composite design was used for determining the effects of reaction temperature (180–260 °C), reaction time (0–2 h) and sawdust concentration (9.1–25 wt%) on conversion and recovered product yields during hydrothermal liquefaction of pine sawdust. The determined conversion and aqueous product (AP) yield were in the range 23.1–57.2% and 14.6–43.4%, respectively. The results showed that all linear model terms and some interaction terms were statistically significant for sawdust conversion and liquid product yields, whereas all quadratic terms were found statistically insignificant. In general, increasing reaction temperature increased sawdust conversion and AP formation, while increasing sawdust concentration led to a reduction in conversion and liquid product yields. The determined model revealed that the decomposition reactions of lignocellulosic constituents may have occurred competitively, thus resulting in a certain trend in recovered AP and heavy oil (HO) yields.

Application of Potent Actinomycete Strains for Bio-Degradation of Domestic Agro-Waste by Composting and Treatment of Pulp-Paper Mill Effluent

Actinomycetes are known to produce an extensive range of bioactive compounds as well as variety of enzymes having multiple biotechnological applications. They are an important source of lignocellulose hydrolyzing enzymes and constitute considerable proportion of the soil or aquatic micro-flora responsible for degradation of biomass in natural environment. Presently, most of the commercially exploited lignocellulases and commercial biodegradation processes rely mostly on fungal or bacterial micro-organisms. Actinomycetes are relatively less explored for biodegradation processes that utilize lignocellulases for solid agro-waste management and waste water treatment. There is also a need to search and explore novel actinomycete strains for various biodegradation applications. This study involved examining the possibility of using only potent actinomycetes strains for the composting process by creating the consortium of such strains that could produce thermo-tolerant and alkali-tolerant key enzymes necessary for the degradation of cellulose, hemi-cellulose and lignin. The newly developed actinomycete consortium was tested for the composting activity and the composting process was optimized. The analysis of the composted material generated under ideal condition, demonstrated desirable physical and chemical characteristics. Paper pulp effluent poses a hazard to waterways due to toxicity. The toxicity of this mill effluent can be attributed to a compound called lignin and its chlorinated derivatives that are let out during the treatment of lignocellulosic constituents. Current study also involves the use of a strain of actinomycete having ability to produce enzyme laccase, which is active under alkaline condition for the treatment of paper pulp effluent. Enzyme laccase is known for its ability to attack phenolic components of lignin and common hazardous component of effluent, polycyclic aromatic hydrocarbons (PAH). Aerobic treatment of effluent by actinomycete strain indicated 21% reduction in COD at pH 7.5 after 14 days under optimum condition. This strain was identified as Streptomyces rochei based on molecular fingerprinting and was reported to be the producer of laccase probably for the first time. LCMS analysis of the treated effluent sample showed the presence of degradation compounds forming after 7 and 14 days of treatment. These compounds showed the degradation of lignin components and other phenolic, non-phenolic components of the effluent by intra molecular re-arrangement, oxidation and ring opening reactions. Overall, potent thermo-tolerant and alkali-tolerant actinomycete strains were successfully isolated and applied for bio-degradation of domestic agro-waste by composting and treatment of pulp-paper mill effluent. The consortium of these strains may be further utilized for scale-up studies in order to assess its commercial feasibility for biodegradation processes.

Hormonal regulation of secondary cell wall formation.

Secondary cell walls (SCWs) have critical functional importance but also constitute a high proportion of the plant biomass and have high application potential. This is true mainly for the lignocellulosic constituents of the SCWs in xylem vessels and fibres, which form a structured layer between the plasma membrane and the primary cell wall (PCW). Specific patterning of the SCW thickenings contributes to the mechanical properties of the different xylem cell types, providing the plant with mechanical support and facilitating the transport of solutes via vessels. In the last decade, our knowledge of the basic molecular mechanisms controlling SCW formation has increased substantially. Several members of the multi-layered regulatory cascade participating in the initiation and transcriptional regulation of SCW formation have been described, and the first cellular components determining the pattern of SCW at the subcellular resolution are being uncovered. The essential regulatory role of phytohormones in xylem development is well known and the molecular mechanisms that link hormonal signals to SCW formation are emerging. Here, we review recent knowledge about the role of individual plant hormones and hormonal crosstalk in the control over the regulatory cascades guiding SCW formation and patterning. Based on the analogy between many of the mechanisms operating during PCW and SCW formation, recently identified mechanisms underlying the hormonal control of PCW remodelling are discussed as potentially novel mechanisms mediating hormonal regulatory inputs in SCW formation.

Thermochemical characterization of cattle manure relevant to its energy conversion and environmental implications

In this work, we used three manure resources from common cattle ruminants (i.e., dairy, beef, and buffalo) to evaluate their thermochemical properties, including elemental analysis, lignocellulosic constituents, calorific value, mineral components, thermogravimetric analysis, Fourier transform infrared spectroscopy, and scanning electron microscopy–energy-dispersive spectroscopy, which were relevant to the utilization as biofuel feedstocks. The fuel-related properties of manures from three different kinds of cattle were very similar. The cattle manure was rich in lignocellulosic constituents with about 80 % on a dry basis, indicating that its calorific value was as high as around 20 MJ/kg in connection with the contents of about 45 % C and 6 % H. More significantly, the contents of sulfur and nitrogen in the cattle manure are relatively low, suggesting that the biomass represents a promising fuel feedstock without concern in the excessive emissions of acidic gases. From the analyses of inorganic elements for the manure, there were no detectable concentrations of heavy metals such as Mn, Cu, and Zn. Based on the results of thermochemical characterization, cattle manure could be directly reused as a fuel feedstock in the direct combustion and co-firing systems or further converted into biochar, activated char, and bio-oil in the thermochemical processes.

사탕수수 부산물의 반탄화 특성에 관한 연구

Torrefaction is a thermal treatment process to pre-treat biomass at temperature of under an inert atmosphere. It was known that torrefaction process strongly depended on the decomposition temperature of the lignocellulosic constituents in biomass. In this work, the torrefaction characteristics of baggase has been studied. This study focuses on the relation between the energy yields, heating values, gas emission, volatile and ash constituents with torrefaction temperatures and times. The activation energies of baggase torrefaction has been studied by using TGA (Thermogravimetric Analyzer). From this work, it was seen that ash constituents and heating values were increased with torrefaction temperature, while volatile constituents and energy yields decreased. It was also found that carbon monoxide containing oxygen were decomposed at a lower temperature than those of hydrocarbon compounds, .

Effect of holding time during pyrolysis on thermochemical and physical properties of biochars derived from goat manure

The utilization of animal manure for biochar production has received much attention mainly due to the global warming and crop production. In this work, goat manure (GM) was evaluated as a potential feedstock for preparing biochars. Its thermochemical characterization was first investigated by the proximate analysis and thermogravimetric analysis (TGA), showing that the biomass obviously comprises a large percentage of lignocellulosic constituents. A series of pyrolysis experiments were conducted to produce biochars from dried GM at different holding times (0, 15, 30, 45, and 60 min) during the pyrolysis of 500 °C. To evaluate their potential for energy use and soil ameliorant, the resulting biochars were subject to the analyses of chemical and physical properties, including proximate analysis, calorific value, pore property (surface area and pore volume) and true density. The results showed that holding time is a less important process parameter influencing the characterization of goat-manure-derived biochars.

Bio-Oils Characteristic from Oil Palm Biomass from Different Fast Pyrolysis Techniques

Pyrolysis is one of the effective ways to convert biomass into energy and value added products. Till date, no comparative study has been done on the characteristic of bio-oils of oil palm shell (OPS) and empty fruit bunch (EFB) from various fast pyrolysis techniques. This includes fluidized bed, fixed bed, rotating cone, microwave and others. Thus, the main objective of this paper was to analyze the characteristics of OPS and EFB bio-oils obtained from these processing techniques. Temperature was found to be the key parameter for the quality of bio-oils. Besides the various pyrolysis techniques, the lignocellulosic constituents of oil palm biomass also influence the chemical composition of the bio-oils. Overall, chemical analysis of OPS and EFB bio-oil through GC-MS has shown variation in the amount of phenol and its derivatives.

Heterologous expression of a Penicillium purpurogenum pectin lyase in Pichia pastoris and its characterization

Lignocellulose is the major component of plant cell walls and it represents a great source of renewable organic matter. One of lignocellulose constituents is pectin. Pectin is composed of two basic structures: a ‘smooth’ region and a ‘hairy’ region. The ‘smooth’ region (homogalacturonan) is a linear polymer of galacturonic acid residues with α-(1→4) linkages, substituted by methyl and acetyl residues. The ‘hairy’ region is more complex, containing xylogalacturonan and rhamnogalacturonans I and II. Among the enzymes which degrade pectin (pectinases) is pectin lyase (E.C. 4.2.2.10). This enzyme acts on highly esterified homogalacturonan, catalysing the cleavage of α-(1→4) glycosidic bonds between methoxylated residues of galacturonic acid by means of β-elimination, with the formation of 4,5-unsaturated products. In this work, the gene and cDNA of a pectin lyase from Penicillium purpurogenum have been sequenced, and the cDNA has been expressed in Pichia pastoris. The gene is 1334 pb long, has three introns and codes for a protein of 376 amino acid residues. The recombinant enzyme was purified to homogeneity and characterized. Pectin lyase has a molecular mass of 45 kDa as determined by SDS-PAGE. It is active on highly esterified pectin, and decreases 40 % the viscosity of pectin with a degree of esterification ≥85 %. The enzyme showed no activity on polygalacturonic acid and pectin from citrus fruit 8 % esterified. The optimum pH and temperature for the recombinant enzyme are 6.0 and 50 °C, respectively, and it is stable up to 50 °C when exposed for 3 h. A purified pectin lyase may be useful in biotechnological applications such as the food industry where the liberation of toxic methanol in pectin degradation should be avoided.

Systematic Isolation and Utilization of Lignocellulosic Components from Sugarcane Bagasse

Lignocellulosic constituents as renewable feedstock can be utilized for various applications. A systematic procedure for separation of cellulose and lignin followed by hydrolysis of hemicelluloses was proposed in this study. Sugarcane bagasse was first subjected to alkaline hydrolysis to remove lignin and hemicelluloses. Then cellulose was separated from the alkali pretreatment residue and further purified. Meanwhile, the obtained pre-hydrolysis liquor (PHL) was acidified to precipitate lignin, and the filtrate was hydrolyzed with 1-methylimidazolium hydrogen sulfate ([Hmim]HSO4) to prepare furfural. Response surface methodology (RSM) was employed to determine optimal conditions for isolation of cellulose. The sequential treatments resulted in a total release of over 77.3% of the original cellulose and 84.5% of the original lignin. In particular, 7.5% yield of furfural was obtained. The structures of the isolated cellulose and lignin were elucidated with Fourier transform infrared spectroscopy (FT-IR).

Treatment of rice straw hemicellulosic hydrolysates with advanced oxidative processes: a new and promising detoxification method to improve the bioconversion process

BackgroundThe use of lignocellulosic constituents in biotechnological processes requires a selective separation of the main fractions (cellulose, hemicellulose and lignin). During diluted acid hydrolysis for hemicellulose extraction, several toxic compounds are formed by the degradation of sugars and lignin, which have ability to inhibit microbial metabolism. Thus, the use of a detoxification step represents an important aspect to be considered for the improvement of fermentation processes from hydrolysates. In this paper, we evaluated the application of Advanced Oxidative Processes (AOPs) for the detoxification of rice straw hemicellulosic hydrolysate with the goal of improving ethanol bioproduction by Pichia stipitis yeast. Aiming to reduce the toxicity of the hemicellulosic hydrolysate, different treatment conditions were analyzed. The treatments were carried out according to a Taguchi L16 orthogonal array to evaluate the influence of Fe+2, H2O2, UV, O3 and pH on the concentration of aromatic compounds and the fermentative process.ResultsThe results showed that the AOPs were able to remove aromatic compounds (furan and phenolic compounds derived from lignin) without affecting the sugar concentration in the hydrolysate. Ozonation in alkaline medium (pH 8) in the presence of H2O2 (treatment A3) or UV radiation (treatment A5) were the most effective for hydrolysate detoxification and had a positive effect on increasing the yeast fermentability of rice straw hemicellulose hydrolysate. Under these conditions, the higher removal of total phenols (above 40%), low molecular weight phenolic compounds (above 95%) and furans (above 52%) were observed. In addition, the ethanol volumetric productivity by P. stipitis was increased in approximately twice in relation the untreated hydrolysate.ConclusionThese results demonstrate that AOPs are a promising methods to reduce toxicity and improve the fermentability of lignocellulosic hydrolysates.

Development of near infrared spectroscopy models for the quantitative prediction of the lignocellulosic components of wet Miscanthus samples

Miscanthus samples were scanned over the visible and near infrared wavelengths at several stages of processing (wet-chopped, air-dried, dried and ground, and dried and sieved). Models were developed to predict lignocellulosic and elemental constituents based on these spectra. The dry and sieved scans gave the most accurate models; however the wet-chopped models for glucose, xylose, and Klason lignin provided excellent accuracies with root mean square error of predictions of 1.27%, 0.54%, and 0.93%, respectively. These models can be suitable for most applications. The wet models for arabinose, Klason lignin, acid soluble lignin, ash, extractives, rhamnose, acid insoluble residue, and nitrogen tended to have lower R2 values (0.80+) for the validation sets and the wet models for galactose, mannose, and acid insoluble ash were less accurate, only having value for rough sample screening. This research shows the potential for online analysis at biorefineries for the major lignocellulosic constituents of interest.