Lignin Content Of Biomass Research Articles

Role of cellulose and lignin on biochar characteristics and removal of diazinon from biochar with a controlled chemical composition

In this study, the effects of carbohydrate and lignin content in biomass on the production of biochar were investigated, and the adsorption behaviors of diazinon on the biochar obtained from delignified oak were evaluated. The lignin content in biomass can be controlled by delignification. Biomass lignin content decreased and cellulose content increased with increasing delignification time, thereby increasing the crystallinity index of delignified oak. Although the biochar yield of the delignified oak decreased, its specific surface area (354.68–444.36 m2/g) and total pore volume (0.162–0.202 cm3/g) were higher than those of the biochar obtained from raw material (193.22 m2/g and 0.093 cm3/g). In the delignified oak, the specific surface area and total pore volume of biochar increased with increasing delignification time. Mesopores and micropores were more developed in the biochar obtained from the delignified oak than in the raw material. The removal efficiency of diazinon by biochar increased with increasing delignification time. Based on the Langmuir and Freundlich isotherms, diazinon adsorption to biochar was suitable for the Langmuir model.

Adsorption of Ni2+ in aqueous solution by KMnO4 modified biomass: investigation on adsorption kinetics and modification mechanism

ABSTRACT In this study, KMnO4 modification was proved to effectively increase the Ni2+ adsorption capacity of biomass. In order to clarify the KMnO4 modification mechanism, the Ni2+ adsorption characteristics of KMnO4 modified corncob (PPCB) under adsorption time, pH and Ni2+ concentration were studied. The results showed that the adsorption was the pseudo second-order kinetic process, indicating that chemisorption was the dominated process, which followed the Langmuir isotherm model and the highest Ni2+ adsorption capacity of PPCB reached 35.6 mg/g. By KMnO4 modification, the corncob was oxidized to generate carboxylates, and the MnO2 (reduction product) was loaded on the modified corncob, both carboxylates and MnO2 increased the Ni2+ adsorption capacity of PPCB. The molecular dynamic results indicated the carboxylate structures had the strongest adsorption capacity. Moreover, the Ni2+ removal efficiency of KMnO4 modified biomass decreased linearly with the increase of lignin content in biomass, while KMnO4 modified lignin showed a good adsorption performance, indicating that the cross-linked structures between lignin and other components in the biomass could inhibit the adsorption capacity of PPCB.

Hydrotropic pretreatment on distillery stillage for efficient cellulosic ethanol production

Effectiveness of hydrotropic delignification using sodium cumene sulfonate for pretreatment of rye, wheat and maize stillage for further use in the production of bioethanol was evaluated. The highest stillage biomass extractives was obtained for a biomass particle size <1.0 mm, when exposed to 131 °C for 1 h at 20% v/v hydrotrope concentration. It has been shown that hydrotropic treatment causes changes in the stillage biomass structure (increase in porosity) and reduces the lignin content in biomass by 7–17%. Delignification with a hydrotrope also increased the concentration of fermentable sugars in the media prepared with stillage biomass, which led to a higher final ethanol concentration (up to ca. 3.5 g/L). Hydrotropic treatment is an effective way of pretreatment of stillage biomass. It provides a high degree of biomass bioconversion and creates the prospect of integrating the 1st and 2nd generation ethanol production process to more fully utilize the raw material.

Fast pyrolysis of biomass catalyzed by magnetic solid base catalyst in a hydrogen atmosphere for selective production of phenol

Phenol is an important phenolic compound widely used in chemical industry. Lignin in lignocellulosic biomass materials has been recognized as a renewable source for phenol production due to its aromatic nature. In the present study, phenol was selectively prepared from fast pyrolysis of biomass using a recyclable magnetic solid base catalyst (K3PO4/Fe3O4, MSB) in an atmosphere with low hydrogen content. The study focused on the influence of pyrolysis atmosphere, pyrolysis temperature, catalyst content, and biomass type on the product distribution, as well as the recycle performance of MSB in consecutive pyrolysis experiments. Results suggested that the synergistic effect of MSB catalyst and hydrogen atmosphere significantly improved the formation of phenol. In a hydrogen atmosphere at MSB to biomass ratio of 1, the maximal phenol yield of 4.3 wt% with the selectivity of 17.6% was obtained from poplar wood pyrolysis at 550°C. Pyrolysis experiments with different biomass materials suggested that the phenol formation was positively correlated with biomass lignin content. A three consecutive run experiment indicated that the MSB catalyst had excellent performance on recovery and recycle. In addition, possible synergistic mechanism between MSB and hydrogen atmosphere was proposed.

Assessing the bioenergy potential of grassland biomass from conservation areas in England

Bioenergy may be one of the ‘ecosystem services of the future’ for grasslands managed for conservation as the concept of bio-based economies is embraced worldwide. Although the idea of producing biogas and bioethanol from lignocellulosic material is not new, there are currently few regional-level comparisons of the bioenergy potential of high-diversity grasslands that would establish whether this could be a competitive bioenergy feedstock for farmers. Comparing the chemical composition and biogas yields of biomass samples from 13 grasslands in England and 73 other bioenergy feedstocks reveals that the lignin content of biomass from grasslands managed for conservation was up to 50% less than other bioenergy crops. Grasslands managed for conservation yielded up to 160% more biogas per ton dry matter than cereals or crop waste and only slightly less than Miscanthus. GIS modeling of the estimated biogas yields of grasslands managed for conservation and fields currently sown with Miscanthus show that grasslands are larger (20.57 ha) than Miscanthus fields (5.95 ha) and are projected to produce up to 117% more biogas per average field. Future incorporation of high-diversity grasslands into local and nation-wide energy plans may help reduce global fossil-fuel use in the 21st century.

The Effect of NaOH Concentration and microwave exposure time to the content of cellulose, hemicellulose and lignin of Corn Cob

Abstract.Currently ethanol produced from molasses, cassava and maize, thereby competing with the need for food, animals feed and other industrial raw materials, so that the supply of raw materials is not continuity. If this continues, it will certainly have an impact on food prices spike, it will create new problems on the economy of the community, and one of an alternative raw material for bioethanol production is cellulose biomass.To convert biomass into bioethanol through several stages, including pretreatment, hydrolysis and fermentation. The content of lignin in biomass will disturb the enzymatic hydrolysis process, so it is necessary to encourage the delignification in the pretreatment stage. Microwave - alkali pretreatment can reduce more lignin and hemicellulose in rice straw, so it needs to be an effort to change the composition of lignocellulose and improve the hydrolysis of corn cob is fermented to become ethanol. Pretreatment of corn cobs research was done using randomized block design arranged in factorial and repeated 2 times. The first factor is the concentration of NaOH for 0,5 N, 1 N and 1,5N. The second factor is the time of exposure to microwave heat radiation for 10, 20 and 30 minutes. The results showed that cellulose content increases with prolonged exposure concentrations of NaOH and microwave, as well as to the content of hemicellulose and lignin decreased along with the increase of exposure duration of Microwave and the increase of NaOH concentrations.

Lignin content of agro-forestry biomass negatively affects the resultant biochar pH

The biomass type is one of the most important factors that affects biochar properties, but the relationship between the major constituents of different biomasses and the properties of the derived biochars, especially the pH, is still unclear. In this study, the cellulose, hemicellulose, lignin, and ash contents of 30 representative agro-forestry biomasses and the pH, surface acid functional groups, and carbonates of 150 resultant biochars prepared with different heat treatment temperatures (HTTs) were examined. The results showed that the lignin content of the biomass had a strong negative correlation with the biochar pH (r = −0.428, P &lt; 0.01). When the HTT was 300 °C, a high lignin content in the biomass was found to have increased the acid functional groups in the biochar, which resulted in a relatively low pH. When the HTT was greater than or equal to 400 °C, the high lignin content in the biomass negatively correlated to the carbonates, which led to a low biochar pH. It was concluded that the lignin content of agro-forestry biomass affects the biochar pH negatively, and the acid functional groups and carbonates have different effects at different HTTs.

Hydrothermal liquefaction of biomass: Influence of temperature and biomass composition on the bio-oil production

Hydrothermal liquefaction is a promising process for the production of high quality bio-oil from biomass. Aim of this study is to investigate the effect of temperature and biomass composition on the yield and quality of bio-oils produced from three different biomass such as natural hay, oak wood and walnut shell. The hydrothermal liquefaction of cellulose was also investigated. The experimental tests, conducted in water sub-critical conditions, were carried out in a microreactor in a temperature range of 240–320°C with a reaction time of 30min. All the products of the process were analyzed and characterized by elemental analysis and GC–MS. It was observed an increase of the bio-oil yields with the lignin content of biomass, being the maximum bio-oil yield obtained for walnut shell and the minimum one for cellulose. This trend is representative of the obtained bio-oils composition, where the phenolic compounds are the major constituents, while the other identified compounds were mainly alcohols, ketones and aldehydes.

Study on susceptibility of CO2-assisted pyrolysis of various biomass to CO2

This study systematically investigates simultaneous genuine roles of CO2 in pyrolysis process by comparing the susceptibility of pyrolysis of various biomass feedstocks (spent coffee ground, oak wood, corn stover, macroalgae, microalgae, cellulose, hemicellulose, and lignin) to CO2: 1) the enhanced thermal cracking of volatile organic carbons (VOCs) evolved from the thermal decomposition of biomass and 2) the direct reaction between VOCs and CO2. The identified roles of CO2 led to the enhanced generation of CO and the subsequent reduction of condensable tar. Even though the influence of CO2 on pyrolysis of various biomass and coal was universal, it exhibited a different magnitude due to the different susceptibility to CO2. This study also reports that the susceptibility to CO2 was contingent on the lignin content in biomass.

Optimization of organic acid pretreatment of wheat straw.

The objective of this study was to determine the effectiveness of different organic acids (maleic, succinic, and oxalic acid) on enzymatic hydrolysis and fermentation yields of wheat straw. It was also aimed to optimize the process conditions (temperature, acid concentration, and pretreatment time) by using response surface methodology (RSM). In line with this objective, the wheat straw samples were pretreated at three different temperatures (170, 190, and 210°C), acid concentrations (1%, 3%, and 5%) and pretreatment time (10, 20, and 30 min). The findings show that at extreme pretreatment conditions, xylose was solubilized in liquid phase, causing an increase in cellulose and lignin content of biomass. Enzymatic hydrolysis experiments revealed that maleic and oxalic acids were quite effective at achieving high sugar yields (>90%) from wheat straw. In contrast, the highest sugar yields were 50-60%, when the samples were pretreated with succinic acid, indicating that succinic acid was not as effective. The optimum process conditions for maleic acid were, 210°C, 1.08% acid concentration, and 19.8 min; for succinic acid 210°C, 5% acid concentration, and 30 min; for oxalic acid 210°C, 3.6% acid concentration, and 16.3 min. The ethanol yields obtained at optimum conditions were 80, 79, and 59% for maleic, oxalic and succinic acid, respectively. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 32:1487-1493, 2016.

Study of solid chemical evolution in torrefaction of different biomasses through solid-state 13C cross-polarization/magic angle spinning NMR (nuclear magnetic resonance) and TGA (thermogravimetric analysis)

The objective of this work is to compare mass loss and chemical evolution of the solid phase, versus time, during dynamic torrefaction of different types of biomass. For this purpose, two experiments, ThermoGravimetric Analysis and solid-state 13C Cross-Polarization/Magic Angle Spinning Nuclear Magnetic Resonance, were run on four representative biomasses. Overall mass loss and chemical evolution of the solid phase were followed, respectively, as a function of temperature and time. Thanks to this coupled information, it was shown that the knowledge of both solid mass loss and chemical evolution is necessary to characterize torrefaction severity. Moreover, biomasses containing higher proportions of xylan lost mass faster than those containing lower proportions. Lignin showed a protecting role towards cellulose, which would lead to a faster degradation of non-woody biomasses in comparison with woody biomasses. Three parameters would have an influence on solid chemical evolution during torrefaction: xylan content in hemicellulose, lignin content in biomass, and cellulose crystallinity.

The dual effects of lignin content on enzymatic hydrolysis using film composed of cellulose and lignin as a structure model

The degree of delignification during pretreatment is a critical question for economic conversion of biomass to sugar platform. Many models have been used to study the optimum lignin content in biomass, but few of them are able to study without disturbances, such as the complex component and structure of biomass. A novel film model composed of only cellulose and lignin was used to investigate the effect of lignin on enzymatic hydrolysis. High lignin–cellulose proportion (10.00–31.25%) hindered enzymatic hydrolysis, whereas low lignin–cellulose proportion (2.00–8.00%) showed a notable potential to promote enzymatic hydrolysis. The enzymatic hydrolysis rate of lignin–cellulose (6.00%) film was 11.5% higher than that of pure cellulose films. Further study indicated that the promotion was due to the enhancement of film porosity and roughness by residual lignin. Thus, based on the biomimetic model, excessive delignification is not recommended in view of efficient conversion and economy.

Rapid and accurate determination of the lignin content of lignocellulosic biomass by solid-state NMR

Biofuels and biomaterials, produced from lignocellulosic feedstock, require facile access to cellulose and hemicellulose to be competitive with petroleum processing and sugar-based fermentation. Physical-chemical barriers resulting from lignin complicates the hydrolysis biomass into fermentable sugars. Thus, the amount of lignin within a substrate is critical in determining biomass processing. The application of 13C cross-polarization, magic-angle spinning, and solid-state nuclear magnetic resonance for the direct quantification of lignin content in biomass is examined. Using a standard curve constructed from pristine lignin and cellulose, the lignin content of a biomass sample is accurately determined through direct measurement without chemical or enzymatic pre-treatment.

Low-lignin mutant biomass resources: Effect of compositional changes on ethanol yield

Low-lignin content bmr (Brown Mid-Rib)-mutant forage sorghum (Sorghum bicolor) grown at Riley and Doniphan counties (Kansas, USA) were compared with wild type high-lignin content forages to evaluate the effect of reduced lignin content in biomass on bioethanol production. Sorghum bagasse (Sorghum bicolor), wheat straw (Triticum aestivum), switchgrass (Panicum virgatum) and miscanthus (Miscanthus giganteus) were used as wild type forages. Ground biomass samples were pretreated with 2% sodium hydroxide at 121°C for 30min followed by enzymatic hydrolysis using cellulase complex and β-glucosidase at high solid loading (20%, W/V), and the sugars released were fermented using Saccharomyces cerevisiae. Lignin content of all types of biomass was reduced to statistically equal levels (2–4%) after alkali pretreatment irrespective of their initial lignin content. However, saccharification efficiency of the pretreated biomass samples varied significantly from each other and showed a weak relationship between saccharification efficiency and total lignin content in raw and/or pretreated biomass. These results indicated that the reduced total lignin content in bmr-mutant crops does not necessarily benefit bioethanol production. Therefore, number of other factors, including lignin structure, crystallinity of cellulose and type of linkages in cellulose-hemicellulose-lignin complex must be further assessed to evaluate new crop lines for bioethanol production. The Fourier transform infrared spectroscopy (FTIR) peak intensities of ester linkages, aromatic CC linkages and glycosidic linkages for raw, pretreated and hydrolyzed biomass samples are in agreement with the variation in saccharification efficiencies among biomass types. Ethanol yield was more than 95% of the maximum possible theoretical yield based on released glucose in all types of biomass, which showed that biomass after alkali pretreatment followed by washing with water does not inhibit S. cerevisiae, regardless of feedstock sources.

Model for Biomass Gasification Including Tar Formation and Evolution

Since tar elimination from the product gas is necessary to make gasification an attractive option, the presence of tar was included in a kinetic model. Lignin was assumed as the main precursor of tars due to its aromatic nature; therefore, the lignin content of biomass was considered as part of the fuel characterization. This work shows the results from the simulation of the fluidized bed gasifier that incorporates the proposed mechanism for tar formation and evolution into the kinetic model. Model results were compared with experimental data from wood gasification. The comparison showed that the model was consistent with what was expected during the evolution of primary tars according to experimental work from previous reports. However, the model overestimated tars of class 2 and the total tar concentration.

Study of enzymatic hydrolysis of mild pretreated lignocellulosic biomasses

The effect of mild acidic and alkaline pretreatments of various plant biomasses on their enzymatic hydrolysis has been studied. The yield of reducing sugars and utilization rate of the biomass were used as reliable characteristics of enzymatic digestibility of the biomasses. The experiments showed that alkaline pretreatment was more efficient than acidic pretreatment. As a result of alkaline pretreatment, a more efficient delignification of the biomasses and considerable improvement of the digestibility parameters were observed. It was found that residual lignin content in the biomass after alkaline pretreatment was related to initial lignin content in untreated biomass. Moreover, residual lignin showed an evident negative effect on enzymatic hydrolysis of pretreated biomass samples, and its removal contributed to higher enzymatic digestibility. It is more preferred to select a mild alkaline pretreatment for biomass that has low content of initial lignin. Such treatment yielded highly delignified biomass with increased percentage of cellulose fraction, which enhanced digestibility at low enzyme loading with a relatively short hydrolysis time.

암모니아 Soaking 방법을 이용한 섬유소계 바이오매스의 전처리 특성

Liberation of fermentable sugars from lignocellulosic biomass is one of the key challenges in production ofcellulosic ethanol. Aqueous ammonia cleaves ether and ester bonds in lignin carbohydrate complexes. It is an effectiveswelling reagent for lignocellulosic biomass. The aqueous ammonia pretreatment selectively reduces the lignin contentof biomass. However, at high temperatures, this process solubilizes more than 50% of the hemicellulose in the biomass.Here we conducted a SAA(Soaking in Aqueous Ammonia) process by moderate reaction temperatures at atmosphericpressure using various lignocellulosicbiomass. The optimum condition of this process was 15 wt% of aqueous ammoniaat 50 of reaction time during 72 hr. The delignification was up to 60% basis on initial biomass and the enzymatic digest-ibility was 60~90% for agricultural biomass, respectively. Key words: Biomass Pretreatment, SAA, Enzymatic Hydrolysis, Bio Ethanol

Pseudo-lignin and pretreatment chemistry

The formation of pseudo-lignin by the combination of carbohydrate and lignin degradation products has been proposed to be responsible for the increased Klason lignin content in biomass pretreated under acidic conditions. Direct evidence for the presence of pseudo-lignin has never been presented. The formation of additional lignin-like material may be detrimental to enzymatic hydrolysis due to the non-productive binding of enzymes with lignin. To investigate the chemistry of pseudo-lignin formation, dilute acid pretreatments were performed on delignified hybrid poplar biomass under conditions of varying severity. The results show a progressive increase in the Klason lignin content of the acid pretreated material with increasing pretreatment severity. NMR and FT-IR spectroscopic characterization shows the development of aliphatic, unsaturated and carbonyl carbon functionalities in the samples pretreated at higher severities. Given the very low Klason lignin content of the starting material, acid catalyzed dehydration of carbohydrates is responsible for the formation of pseudo-lignin.

Increase in 4-Coumaryl Alcohol Units during Lignification in Alfalfa (Medicago sativa) Alters the Extractability and Molecular Weight of Lignin

The lignin content of biomass can impact the ease and cost of biomass processing. Lignin reduction through breeding and genetic modification therefore has potential to reduce costs in biomass-processing industries (e.g. pulp and paper, forage, and lignocellulosic ethanol). We investigated compositional changes in two low-lignin alfalfa (Medicago sativa) lines with antisense down-regulation of p-coumarate 3-hydroxylase (C3H) or hydroxycinnamoyl-CoA:shikimate hydroxycinnamoyltransferase (HCT). We investigated whether the difference in reactivity during lignification of 4-coumaryl alcohol (H) monomers versus the naturally dominant sinapyl alcohol and coniferyl alcohol lignin monomers alters the lignin structure. Sequential base extraction readily reduced the H monomer content of the transgenic lines, leaving a residual lignin greatly enriched in H subunits; the extraction profile highlighted the difference between the control and transgenic lines. Gel permeation chromatography of isolated ball-milled lignin indicated significant changes in the weight average molecular weight distribution of the control versus transgenic lines (CTR1a, 6000; C3H4a, 5500; C3H9a, 4000; and HCT30a, 4000).

Rapid Assessment of Lignin Content and Structure in Switchgrass (Panicum virgatum L.) Grown Under Different Environmental Conditions

Switchgrass (Panicum virgatum L.) is a candidate feedstock in bioenergy, and plant breeding and molecular genetic strategies are being used to improve germplasm. In order to assess these subsequent modifications, baseline biomass compositional data are needed in a relevant variety of environments. In this study, switchgrass cv. Alamo was grown in the field, greenhouse, and growth chamber and harvested into individual leaf and stem tissue components. These components were analyzed with pyrolysis vapor analysis using molecular beam mass spectrometry, Fourier transform infrared, and standard wet chemistry methods to characterize and compare the composition among the different growth environments. The details of lignin content, S/G ratios, and degree of cross-linked lignin are discussed. Multivariate approaches such as projection to latent structures regression found a very strong correlation between the lignin content obtained by standard wet chemistry methods and the two high throughput techniques employed to rapidly assess lignin in potential switchgrass candidates. The models were tested on unknown samples and verified by wet chemistry. The similar lignin content found by the two methods shows that both approaches are capable of determining lignin content in biomass in a matter of minutes.