Cinnamyl alcohol dehydrogenase （CAD） is a key enzyme involved in the last step of monolignol biosynthesis. The effect of CAD down-regulation on lignin production was investigated through a transgenic approach in mai...Cinnamyl alcohol dehydrogenase （CAD） is a key enzyme involved in the last step of monolignol biosynthesis. The effect of CAD down-regulation on lignin production was investigated through a transgenic approach in maize. Trans- genic CAD-RNAi plants show a different degree of enzymatic reduction depending on the analyzed tissue and show alter- ations in cell wall composition. Cell walls of CAD-RNAi stems contain a lignin polymer with a slight reduction in the S-to-G ratio without affecting the total lignin content. In addition, these cell walls accumulate higher levels of cellulose and ara- binoxylans. In contrast, cell walls of CAD-RNAi midribs present a reduction in the total lignin content and of cell wall polysaccharides. In vitro degradability assays showed that, although to a different extent, the changes induced by the repression of CAD activity produced midribs and stems more degradable than wild-type plants. CAD-RNAi plants grown in the field presented a wild-type phenotype and produced higher amounts of dry biomass. Cellulosic bioethanol assays revealed that CAD-RNAi biomass produced higher levels of ethanol compared to wild-type, making CAD a good target to improve both the nutritional and energetic values of maize lignocellulosic biomass.展开更多
The conversion of lignocellulosic biomass into biofuels or biochemicals typically involves a pretreatment process followed by the enzyme-catalyzed hydrolysis of cellulose and hemicellulose components to fermentable su...The conversion of lignocellulosic biomass into biofuels or biochemicals typically involves a pretreatment process followed by the enzyme-catalyzed hydrolysis of cellulose and hemicellulose components to fermentable sugars.Many factors can contribute to the recalcitrance of biomass,e.g.,the lignin content and structure,crystallinity of cellulose,degree of fiber polymerization,and hemicellulose content,among others.However,nonproductive binding between cellulase and lignin is the factor with the greatest impact on enzymatic hydrolysis.To reduce the nonproductive adsorption of enzymes on lignin and improve the efficiency of enzymatic hydrolysis,this review comprehensively summarized the progress that has been made in understanding the interactions between lignin and enzymes.Firstly,the effects of pretreatment techniques on lignin content and enzymatic hydrolysis were reviewed.The effects of lignin content and functional groups on enzymatic hydrolysis were then summarized.Methods for the preparation and characterization of lignin films were assessed.Finally,the methods applied to characterize the interactions between lignin and cellulase were reviewed,and methods for decreasing the nonproductive binding of enzymes to lignin were discussed.This review provides an overview of the current understanding of how lignin hinders the enzymatic hydrolysis of lignocellulosic biomass,and provides a theoretical basis for the development of more economical and effective methods and additives to reduce the interaction of lignin and enzymes to improve the efficiency of enzymatic hydrolysis.展开更多
Bioconversion of lignocellulosic biomass to ethanol is significantly hindered by the structural and chemical complexity of biomass,which makes these materials a challenge to be used as feedstocks for cellulosic ethano...Bioconversion of lignocellulosic biomass to ethanol is significantly hindered by the structural and chemical complexity of biomass,which makes these materials a challenge to be used as feedstocks for cellulosic ethanol production.Cellulose and hemicellulose,when hydrolyzed into their component sugars,can be converted into ethanol through well established fermentation technologies.However,sugars necessary for fermentation are trapped inside the crosslinking structure of the lignocellulose.Hence,pretreatment of biomass is always necessary to remove and/or modify the surrounding matrix of lignin and hemicellulose prior to the enzymatic hydrolysis of the polysaccharides(cellulose and hemicellulose)in the biomass.Pretreatment refers to a process that converts lignocellulosic biomass from its native form,in which it is recalcitrant to cellulase enzyme systems,into a form for which cellulose hydrolysis is much more effective.In general,pretreatment methods can be classified into three categories,including physical,chemical,and biological pretreatment.The subject of this paper emphasizes the biomass pretreatment in preparation for enzymatic hydrolysis and microbial fermentation for cellulosic ethanol production.It primarily covers the impact of biomass structural and compositional features on the pretreatment,the characteristics of different pretreatment methods,the pretreatment study status,challenges,and future research targets.展开更多
The rapid increase in energy demand,the extensive use of fossil fuels and the urgent need to reduce the carbon dioxide emissions have raised concerns in the transportation sector.Alternate renewable and sustainable so...The rapid increase in energy demand,the extensive use of fossil fuels and the urgent need to reduce the carbon dioxide emissions have raised concerns in the transportation sector.Alternate renewable and sustainable sources have become the ultimate solution to overcome the expected depletion of fossil fuels.The conversion of lignocellulosic biomass to liquid(BtL)transportation fuels seems to be a promising path and presents advantages over first generation biofuels and fossil fuels.Therefore,development of BtL systems is critical to increase the potential of this resource in a sustainable and economic way.Conversion of lignocellulosic BtL transportation fuels,such as,gasoline,diesel and jet fuel can be accomplished through various thermochemical processes and processing routes.The major steps for the production of BtL fuels involve feedstock selection,physical pretreatment,production of bio-oil,upgrading of bio-oil to transportation fuels and recovery of value-added products.The present work is aiming to give a comprehensive review of the current process technologies following these major steps and the current scenarios of biomass to liquid facilities for the production of biofuels.展开更多
Supercritical carbon dioxide,with water-ethanol as co-solvent,was applied to pretreat corn stover to enhance its enzymatic hydrolysis.The efficiency of pretreatment was evaluated by the final reducing sugar yield obta...Supercritical carbon dioxide,with water-ethanol as co-solvent,was applied to pretreat corn stover to enhance its enzymatic hydrolysis.The efficiency of pretreatment was evaluated by the final reducing sugar yield obtained from the enzymatic hydrolysis of cellulose.Under the operation conditions of pretreatment pressure 15 MPa,temperature 180 ℃ and time 1 h,the optimal sugar yield of 77.8℅ was obtained.Scanning electron microscopy(SEM) and chemical composition analysis were applied to the pretreated corn stover.The results showed that the surface morphology and microscopic structure of pretreated corn stover were greatly changed.After the pretreatment,the contents of hemicellulose and lignin were reduced obviously.Thus more cellulose was exposed,increasing the sugar yield.展开更多
Cellulosic ethanol has been identified as a crucial biofuel resource due to its sustainability and abundance of cellulose feedstocks. However, current methods to obtain glucose from lignocellulosic biomass are ineffec...Cellulosic ethanol has been identified as a crucial biofuel resource due to its sustainability and abundance of cellulose feedstocks. However, current methods to obtain glucose from lignocellulosic biomass are ineffective due to recalcitrance of plant biomass. Insects have evolved endogenous and symbiotic enzymes to efficiently use lignocellulosic material as a source of metabolic glucose. Even though traditional biochemical methods have been used to identify and characterize these enzymes, the advancement of genomic and proteomic research tools are expected to allow new insights into insect digestion of cellulose. This information is highly relevant to the design of improved industrial processes ofbiofuel production and to identify potential new targets for development of insecticides. This review describes the diverse methodologies used to detect, quantify, purify, clone and express cellulolytic enzymes from insects, as well as their advantages and limitations.展开更多
Lignocellulosic biomass has attracted great interest in recent years for energy production due to its renewability and carbon-neutral nature.There are various ways to convert lignocellulose to gaseous,liquid and solid...Lignocellulosic biomass has attracted great interest in recent years for energy production due to its renewability and carbon-neutral nature.There are various ways to convert lignocellulose to gaseous,liquid and solid fuels via thermochemical,chemical or biological approaches.Typical biomass derived fuels include syngas,bio-gas,bio-oil,bioethanol and biochar,all of which could be used as fuels for furnace,engine,turbine or fuel cells.Direct biomass fuel cells mediated by various electron carriers provide a new direction of lignocellulose conversion.Various metal and non-metal based carriers have been screened for mediating the electron transfer from biomass to oxygen thus generating electricity.The power density of direct biomass fuel cells can be over 100 mW cm^(-2),which shows promise for practical applications.Lignocellulose and its isolated components,primarily cellulose and lignin,have also been paid considerable attention as sustainable carbonaceous materials for preparation of electrodes for supercapacitors,lithium-ion batteries and lithium-sulfur batteries.In this paper,we have provided a state-of-the-art review on the research progress of lignocellulosic biomass as feedstock and materials for power generation and energy storage focusing on the chemistry aspects of the processes.It was recommended that process integration should be performed to reduce the cost for thermochemical and biological conversion of lignocellulose to biofuels,while efforts should be made to increase efficiency and improve the properties for biomass fuelled fuel cells and biomass derived electrodes for energy storage.展开更多
The current irrational use of fossil fuels and the impact of greenhouse gases on the environment are driving research into renewable energy production from organic resources and waste. The global energy demand is high...The current irrational use of fossil fuels and the impact of greenhouse gases on the environment are driving research into renewable energy production from organic resources and waste. The global energy demand is high, and most of this energy is produced from fossil resources. Recent studies report that anaerobic di- gestion （AD） is an efficient alternative technology that combines biofuel production with sustainable waste management, and various technological trends exist in the biogas industry that enhance the production and quality of biogas. Further investments in AD are expected to meet with increasing success due to the low cost of available feedstocks and the wide range of uses for biogas （i.e., for heating, electricity, and fuel）. Bio- gas production is growing in the European energy market and offers an economical alternative for bioenergy production. The objective of this work is to provide an overview of biogas production from lignocellulosic waste, thus providing information toward crucial issues in the biogas economy.展开更多
The concept of integrated forest biorefineries(IFBRs) has gained significant interest.The prehydrolysis kraft(PHK) dissolving pulp production process is a suitable example of IFBR concept for the production of dissolv...The concept of integrated forest biorefineries(IFBRs) has gained significant interest.The prehydrolysis kraft(PHK) dissolving pulp production process is a suitable example of IFBR concept for the production of dissolving pulp and utilization of dissolved hemicelluloses,acetic acid,and lignin in the prehydrolysis liquor(PHL).This review paper highlights recent progress related to the recovery and utilization of dissolved organics(e.g.,hemicelluloses,acetic acid,and lignin) in the PHL of the PHK dissolving pulp production process.Integrated multi-step recovery and separation processes have been developed for this purpose to accommodate the complex nature of the PHL.Potential products,including xylan-based compounds,acetic acid,and lignin,are also discussed in detail.展开更多
Lignocellulosic biomass offers the most abundant renewable resource in replacing traditional fossil resources. However, it is still a major challenge to directly convert the lignin component into value-added materials...Lignocellulosic biomass offers the most abundant renewable resource in replacing traditional fossil resources. However, it is still a major challenge to directly convert the lignin component into value-added materials. The availability of plentiful hydroxyl groups in lignin macromolecules and its unique three-dimensional structure make it an ideal precursor for mesoporous biosorbents. In this work, we reported an environmentally friendly and economically feasible method for the fabrication of mesoporous lignin-based biosorbent （MLBB） from lignocellulosic biomass through a SOB micro-thermal-explosion process, as a byproduct of microcrystalline cellulose. BET analysis reveal the average pore-size distribution of 5.50 nm, the average pore value of 0.35 cm3/g, and the specific surface area of 186 m2/g. The physicochemical properties of MLBB were studied by fourier transform infrared spectroscopy （FTIR）, attenuated-total-reflection fourier transform infrared spectroscopy （ATR-FTIR）, X-ray photoelectron spectroscopy （XPS）, and element analysis. These results showed that there are large amounts of sutfonic functional groups existing on the surface of this biosorbent. Pb（II） was used as a model heavy-metal-ion to demonstrate the technical feasibility for heavy-metal-ion removal. Considering that lignocellulosic biomass is a naturally abundant and renewable resource and SO3 micro-thermal-explosion is a proven technique, this biosorbent can be easily produced at large scale and become a sustainable and reliable resource for wastewater treatment.展开更多
The removal of chromium(Cr)from wastewater by various adsorbents has been investigated.As compared with the commercial activated carbon,the biosorbents with inexpensive and high adsorption capacities are developed fro...The removal of chromium(Cr)from wastewater by various adsorbents has been investigated.As compared with the commercial activated carbon,the biosorbents with inexpensive and high adsorption capacities are developed from lignocellulosic wastes.Lignin,existing in lignocellulosic biomass,is the second most abundant resource in nature.Recently,lignin-based bio-sorbents were served as an advanced novel material for the metal ions and dye adsorption from wastewater.It has showed several advantages in the wastewater treatments because of the lowcost,high adsorption capacity,easy recover,and possibility of metal recovery.In this review,the isolation of lignin from lignocellulosic biomass was summarized,and the structural characteristics of lignin were comparably analyzed.The modification of lignin was performed to obtain a large surface area,strong binding-site,and high and quick adsorption properties of lignin-based adsorption materials.The adsorption efficiency of Cr ions was found to be strongly dependent on the pH of the wastewater.To further illustrate the adsorption process,the structural changes and the interactions between the metal ions and the functional groups of the lignin-based biosorbents in the adsorption process should be further investigated.Once the cost-effective and high-efficiency modification techniques are developed,lignin-based adsorbents can be expected to be the most suitable alternatives for Cr ions removal from wastewater in industry.展开更多
The current trend of replacing a percentage of gasoline with ethanol has promoted the development of new processes for its production from lignocellulosic biomass. This work reports the production of ethanol from the ...The current trend of replacing a percentage of gasoline with ethanol has promoted the development of new processes for its production from lignocellulosic biomass. This work reports the production of ethanol from the Camalote grass (Paspalum fasciculatum Willd). The lignocellulosic biomass was subjected to acid hydrolysis at 125C and 15 psi with H2SO4 concentrations at 5%, 10%, and 20%, obtaining an average of reducing sugars (pentoses and hexoses) from the hydrolyzed juice with 12.3%, 10%, and 17% Brix, respectively. The sugars were fermented using yeast of the Saccharomyces cerevisiae at 30C for 48 hours. Finally, the ethanol was distilled at 78C, and the average yields were obtained through analysis of variance with a 95% confidence level. The values indicate that there is a significant difference (p > 0.05), the Tukey study shows that all the % v/v averages are different from each other. For H2SO4 concentration at 5% (10.33 ± 2), H2SO4 at 10% (9.33 ± 1.8), and H2SO4 at 20% (6.33 ± 2). The acidity analysis for the ethanol obtained from each treatment gave a value of 1.8 mg/L of acetic acid in all cases.展开更多
Ethanol production from lignocellulosic waste has attracted considerable attention because of its feasi- bility and the generation of valuable products. Previous studies have shown that pretreatment and hydrolysis are...Ethanol production from lignocellulosic waste has attracted considerable attention because of its feasi- bility and the generation of valuable products. Previous studies have shown that pretreatment and hydrolysis are key processes for lignocellulose conversion. Hydrothermal process is a promising technique because of its efficiency to break down the lignocellulosic structures and produce fermentable hexoses. Most studies in this field have therefore focused on understanding these processes or optimizing the parameters, but commonly reported low yields of fermentable hexoses. The inability to produce high yields of fermentable hexoses is mainly attributed to inadequate information on the conversion mechanisms of lignocellulose, particularly the reaction rules of dissolu- tion, which is a limiting step in the entire conversion process. This paper critically reviewed the progress done in the research and development of the hydrothermal dissolution and hydrolysis of lignocellulose. Principles, processes, and related studies on separate dissolution and asynchronous hydrolysis of lignin, hemieellulose, and cellulose are presented. Potential research prospects are also suggested.展开更多
The main feedstocks for bioethanol are sugarcane （Saccharum offic- inarum） and maize （Zea mays）, both of which are C4 grasses, highly efficient at converting solar energy into chemical energy, and both are food cr...The main feedstocks for bioethanol are sugarcane （Saccharum offic- inarum） and maize （Zea mays）, both of which are C4 grasses, highly efficient at converting solar energy into chemical energy, and both are food crops. As the systems for lignocellulosic bioethanol production become more efficient and cost effective, plant biomass from any source may be used as a feedstock for bioethanol production. Thus, a move away from using food plants to make fuel is possible, and sources of biomass such as wood from forestry and plant waste from cropping may be used. However, the bioethanol industry will need a continuous and reliable supply of biomass that can be produced at a low cost and with minimal use of water, fertilizer and arable land. As many C4 plants have high light, water and nitrogen use efficiency, as compared with C3 species, they are ideal as feedstock crops. We consider the productivity and resource use of a number of candidate plant species, and discuss biomass ＇quality＇, that is, the composition of the plant cell wall.展开更多
Lignocellulosic biomass can be circulated to produce many materials and products,including biochar.This study analyzed five different types of biochar produced from agricultural wastes and wood residues.The raw materi...Lignocellulosic biomass can be circulated to produce many materials and products,including biochar.This study analyzed five different types of biochar produced from agricultural wastes and wood residues.The raw materials included three agricultural by-products:corncob,cassava rhizome,rice husk,and two types of wood residues:rain tree(Samanea saman(Jacq.)Merr.)and krachid(Streblus ilicifolius(Vidal)Corner.).The biochar were made in patented retorts with locally-appropriated technology at a temper-ature range of 450e500C.This research focuses on the primary physicochemical properties and biochar components,allowing biochar to become a vital material to support sustainable agriculture and the environment.Biochar properties used for agriculture consist of specific surface area,total pore volume,average pore diameter,pH,electrical conductivity(EC),and cation exchange capacity(CEC).The prop-erties that benefit the environmental purposes are the element:carbon(C),hydrogen(H),nitrogen(N),oxygen(O),and the molar ratio of H/C,O/C,and C/N.The study found that all five types of biochar contained suitable properties for soil amendment and carbon sequestration.However,significant dif-ferences were shown in specific surface area,average pore diameter,pH,CEC,and EC of various biochar.Based on O/C and H/C ratios,all five types of biochar persisted in soil from 100 to over 1,000 years.展开更多
文摘Cinnamyl alcohol dehydrogenase （CAD） is a key enzyme involved in the last step of monolignol biosynthesis. The effect of CAD down-regulation on lignin production was investigated through a transgenic approach in maize. Trans- genic CAD-RNAi plants show a different degree of enzymatic reduction depending on the analyzed tissue and show alter- ations in cell wall composition. Cell walls of CAD-RNAi stems contain a lignin polymer with a slight reduction in the S-to-G ratio without affecting the total lignin content. In addition, these cell walls accumulate higher levels of cellulose and ara- binoxylans. In contrast, cell walls of CAD-RNAi midribs present a reduction in the total lignin content and of cell wall polysaccharides. In vitro degradability assays showed that, although to a different extent, the changes induced by the repression of CAD activity produced midribs and stems more degradable than wild-type plants. CAD-RNAi plants grown in the field presented a wild-type phenotype and produced higher amounts of dry biomass. Cellulosic bioethanol assays revealed that CAD-RNAi biomass produced higher levels of ethanol compared to wild-type, making CAD a good target to improve both the nutritional and energetic values of maize lignocellulosic biomass.
基金financially supported by Innovation Project of Guangxi Graduate Education (YCBZ2019017)Guangxi Natural Science Fund (2018JJA130224)Guangxi Key Laboratory of Clean Pulping and Pollution Control Fund (ZR2018057)
文摘The conversion of lignocellulosic biomass into biofuels or biochemicals typically involves a pretreatment process followed by the enzyme-catalyzed hydrolysis of cellulose and hemicellulose components to fermentable sugars.Many factors can contribute to the recalcitrance of biomass,e.g.,the lignin content and structure,crystallinity of cellulose,degree of fiber polymerization,and hemicellulose content,among others.However,nonproductive binding between cellulase and lignin is the factor with the greatest impact on enzymatic hydrolysis.To reduce the nonproductive adsorption of enzymes on lignin and improve the efficiency of enzymatic hydrolysis,this review comprehensively summarized the progress that has been made in understanding the interactions between lignin and enzymes.Firstly,the effects of pretreatment techniques on lignin content and enzymatic hydrolysis were reviewed.The effects of lignin content and functional groups on enzymatic hydrolysis were then summarized.Methods for the preparation and characterization of lignin films were assessed.Finally,the methods applied to characterize the interactions between lignin and cellulase were reviewed,and methods for decreasing the nonproductive binding of enzymes to lignin were discussed.This review provides an overview of the current understanding of how lignin hinders the enzymatic hydrolysis of lignocellulosic biomass,and provides a theoretical basis for the development of more economical and effective methods and additives to reduce the interaction of lignin and enzymes to improve the efficiency of enzymatic hydrolysis.
文摘Bioconversion of lignocellulosic biomass to ethanol is significantly hindered by the structural and chemical complexity of biomass,which makes these materials a challenge to be used as feedstocks for cellulosic ethanol production.Cellulose and hemicellulose,when hydrolyzed into their component sugars,can be converted into ethanol through well established fermentation technologies.However,sugars necessary for fermentation are trapped inside the crosslinking structure of the lignocellulose.Hence,pretreatment of biomass is always necessary to remove and/or modify the surrounding matrix of lignin and hemicellulose prior to the enzymatic hydrolysis of the polysaccharides(cellulose and hemicellulose)in the biomass.Pretreatment refers to a process that converts lignocellulosic biomass from its native form,in which it is recalcitrant to cellulase enzyme systems,into a form for which cellulose hydrolysis is much more effective.In general,pretreatment methods can be classified into three categories,including physical,chemical,and biological pretreatment.The subject of this paper emphasizes the biomass pretreatment in preparation for enzymatic hydrolysis and microbial fermentation for cellulosic ethanol production.It primarily covers the impact of biomass structural and compositional features on the pretreatment,the characteristics of different pretreatment methods,the pretreatment study status,challenges,and future research targets.
基金financial support from CONACYT-The Mexican National Council for Science and Technology (REFERENCE: 326204/439098)the University of Southern Denmark
文摘The rapid increase in energy demand,the extensive use of fossil fuels and the urgent need to reduce the carbon dioxide emissions have raised concerns in the transportation sector.Alternate renewable and sustainable sources have become the ultimate solution to overcome the expected depletion of fossil fuels.The conversion of lignocellulosic biomass to liquid(BtL)transportation fuels seems to be a promising path and presents advantages over first generation biofuels and fossil fuels.Therefore,development of BtL systems is critical to increase the potential of this resource in a sustainable and economic way.Conversion of lignocellulosic BtL transportation fuels,such as,gasoline,diesel and jet fuel can be accomplished through various thermochemical processes and processing routes.The major steps for the production of BtL fuels involve feedstock selection,physical pretreatment,production of bio-oil,upgrading of bio-oil to transportation fuels and recovery of value-added products.The present work is aiming to give a comprehensive review of the current process technologies following these major steps and the current scenarios of biomass to liquid facilities for the production of biofuels.
文摘Supercritical carbon dioxide,with water-ethanol as co-solvent,was applied to pretreat corn stover to enhance its enzymatic hydrolysis.The efficiency of pretreatment was evaluated by the final reducing sugar yield obtained from the enzymatic hydrolysis of cellulose.Under the operation conditions of pretreatment pressure 15 MPa,temperature 180 ℃ and time 1 h,the optimal sugar yield of 77.8℅ was obtained.Scanning electron microscopy(SEM) and chemical composition analysis were applied to the pretreated corn stover.The results showed that the surface morphology and microscopic structure of pretreated corn stover were greatly changed.After the pretreatment,the contents of hemicellulose and lignin were reduced obviously.Thus more cellulose was exposed,increasing the sugar yield.
文摘Cellulosic ethanol has been identified as a crucial biofuel resource due to its sustainability and abundance of cellulose feedstocks. However, current methods to obtain glucose from lignocellulosic biomass are ineffective due to recalcitrance of plant biomass. Insects have evolved endogenous and symbiotic enzymes to efficiently use lignocellulosic material as a source of metabolic glucose. Even though traditional biochemical methods have been used to identify and characterize these enzymes, the advancement of genomic and proteomic research tools are expected to allow new insights into insect digestion of cellulose. This information is highly relevant to the design of improved industrial processes ofbiofuel production and to identify potential new targets for development of insecticides. This review describes the diverse methodologies used to detect, quantify, purify, clone and express cellulolytic enzymes from insects, as well as their advantages and limitations.
基金supported by the National Natural Science Foundation of China(No.21878176)National Key Research and Development Program of China(No.2018YFA0902200)financially supported by the Imperial College President’s PhD Scholarship Scheme。
文摘Lignocellulosic biomass has attracted great interest in recent years for energy production due to its renewability and carbon-neutral nature.There are various ways to convert lignocellulose to gaseous,liquid and solid fuels via thermochemical,chemical or biological approaches.Typical biomass derived fuels include syngas,bio-gas,bio-oil,bioethanol and biochar,all of which could be used as fuels for furnace,engine,turbine or fuel cells.Direct biomass fuel cells mediated by various electron carriers provide a new direction of lignocellulose conversion.Various metal and non-metal based carriers have been screened for mediating the electron transfer from biomass to oxygen thus generating electricity.The power density of direct biomass fuel cells can be over 100 mW cm^(-2),which shows promise for practical applications.Lignocellulose and its isolated components,primarily cellulose and lignin,have also been paid considerable attention as sustainable carbonaceous materials for preparation of electrodes for supercapacitors,lithium-ion batteries and lithium-sulfur batteries.In this paper,we have provided a state-of-the-art review on the research progress of lignocellulosic biomass as feedstock and materials for power generation and energy storage focusing on the chemistry aspects of the processes.It was recommended that process integration should be performed to reduce the cost for thermochemical and biological conversion of lignocellulose to biofuels,while efforts should be made to increase efficiency and improve the properties for biomass fuelled fuel cells and biomass derived electrodes for energy storage.
文摘The current irrational use of fossil fuels and the impact of greenhouse gases on the environment are driving research into renewable energy production from organic resources and waste. The global energy demand is high, and most of this energy is produced from fossil resources. Recent studies report that anaerobic di- gestion （AD） is an efficient alternative technology that combines biofuel production with sustainable waste management, and various technological trends exist in the biogas industry that enhance the production and quality of biogas. Further investments in AD are expected to meet with increasing success due to the low cost of available feedstocks and the wide range of uses for biogas （i.e., for heating, electricity, and fuel）. Bio- gas production is growing in the European energy market and offers an economical alternative for bioenergy production. The objective of this work is to provide an overview of biogas production from lignocellulosic waste, thus providing information toward crucial issues in the biogas economy.
文摘The concept of integrated forest biorefineries(IFBRs) has gained significant interest.The prehydrolysis kraft(PHK) dissolving pulp production process is a suitable example of IFBR concept for the production of dissolving pulp and utilization of dissolved hemicelluloses,acetic acid,and lignin in the prehydrolysis liquor(PHL).This review paper highlights recent progress related to the recovery and utilization of dissolved organics(e.g.,hemicelluloses,acetic acid,and lignin) in the PHL of the PHK dissolving pulp production process.Integrated multi-step recovery and separation processes have been developed for this purpose to accommodate the complex nature of the PHL.Potential products,including xylan-based compounds,acetic acid,and lignin,are also discussed in detail.
基金the National Science Foundation of China(No.21207031)the National High Technology Research of China(863)(No.2014AA021902)for the partial support of this study
文摘Lignocellulosic biomass offers the most abundant renewable resource in replacing traditional fossil resources. However, it is still a major challenge to directly convert the lignin component into value-added materials. The availability of plentiful hydroxyl groups in lignin macromolecules and its unique three-dimensional structure make it an ideal precursor for mesoporous biosorbents. In this work, we reported an environmentally friendly and economically feasible method for the fabrication of mesoporous lignin-based biosorbent （MLBB） from lignocellulosic biomass through a SOB micro-thermal-explosion process, as a byproduct of microcrystalline cellulose. BET analysis reveal the average pore-size distribution of 5.50 nm, the average pore value of 0.35 cm3/g, and the specific surface area of 186 m2/g. The physicochemical properties of MLBB were studied by fourier transform infrared spectroscopy （FTIR）, attenuated-total-reflection fourier transform infrared spectroscopy （ATR-FTIR）, X-ray photoelectron spectroscopy （XPS）, and element analysis. These results showed that there are large amounts of sutfonic functional groups existing on the surface of this biosorbent. Pb（II） was used as a model heavy-metal-ion to demonstrate the technical feasibility for heavy-metal-ion removal. Considering that lignocellulosic biomass is a naturally abundant and renewable resource and SO3 micro-thermal-explosion is a proven technique, this biosorbent can be easily produced at large scale and become a sustainable and reliable resource for wastewater treatment.
基金the financial support by the Central Universities,Beijing Forestry University(2017-17)Chang’an University(300102299203)+2 种基金National Science Foundation of China(41702367)the National Science Foundation of China for a Key Project(31430092)the National Key R&D Program of China(2017YFB0307903).
文摘The removal of chromium(Cr)from wastewater by various adsorbents has been investigated.As compared with the commercial activated carbon,the biosorbents with inexpensive and high adsorption capacities are developed from lignocellulosic wastes.Lignin,existing in lignocellulosic biomass,is the second most abundant resource in nature.Recently,lignin-based bio-sorbents were served as an advanced novel material for the metal ions and dye adsorption from wastewater.It has showed several advantages in the wastewater treatments because of the lowcost,high adsorption capacity,easy recover,and possibility of metal recovery.In this review,the isolation of lignin from lignocellulosic biomass was summarized,and the structural characteristics of lignin were comparably analyzed.The modification of lignin was performed to obtain a large surface area,strong binding-site,and high and quick adsorption properties of lignin-based adsorption materials.The adsorption efficiency of Cr ions was found to be strongly dependent on the pH of the wastewater.To further illustrate the adsorption process,the structural changes and the interactions between the metal ions and the functional groups of the lignin-based biosorbents in the adsorption process should be further investigated.Once the cost-effective and high-efficiency modification techniques are developed,lignin-based adsorbents can be expected to be the most suitable alternatives for Cr ions removal from wastewater in industry.
文摘The current trend of replacing a percentage of gasoline with ethanol has promoted the development of new processes for its production from lignocellulosic biomass. This work reports the production of ethanol from the Camalote grass (Paspalum fasciculatum Willd). The lignocellulosic biomass was subjected to acid hydrolysis at 125C and 15 psi with H2SO4 concentrations at 5%, 10%, and 20%, obtaining an average of reducing sugars (pentoses and hexoses) from the hydrolyzed juice with 12.3%, 10%, and 17% Brix, respectively. The sugars were fermented using yeast of the Saccharomyces cerevisiae at 30C for 48 hours. Finally, the ethanol was distilled at 78C, and the average yields were obtained through analysis of variance with a 95% confidence level. The values indicate that there is a significant difference (p > 0.05), the Tukey study shows that all the % v/v averages are different from each other. For H2SO4 concentration at 5% (10.33 ± 2), H2SO4 at 10% (9.33 ± 1.8), and H2SO4 at 20% (6.33 ± 2). The acidity analysis for the ethanol obtained from each treatment gave a value of 1.8 mg/L of acetic acid in all cases.
文摘Ethanol production from lignocellulosic waste has attracted considerable attention because of its feasi- bility and the generation of valuable products. Previous studies have shown that pretreatment and hydrolysis are key processes for lignocellulose conversion. Hydrothermal process is a promising technique because of its efficiency to break down the lignocellulosic structures and produce fermentable hexoses. Most studies in this field have therefore focused on understanding these processes or optimizing the parameters, but commonly reported low yields of fermentable hexoses. The inability to produce high yields of fermentable hexoses is mainly attributed to inadequate information on the conversion mechanisms of lignocellulose, particularly the reaction rules of dissolu- tion, which is a limiting step in the entire conversion process. This paper critically reviewed the progress done in the research and development of the hydrothermal dissolution and hydrolysis of lignocellulose. Principles, processes, and related studies on separate dissolution and asynchronous hydrolysis of lignin, hemieellulose, and cellulose are presented. Potential research prospects are also suggested.
基金supported by the Australian Research Council (ARC) though ARC-linkage project LP0883808
文摘The main feedstocks for bioethanol are sugarcane （Saccharum offic- inarum） and maize （Zea mays）, both of which are C4 grasses, highly efficient at converting solar energy into chemical energy, and both are food crops. As the systems for lignocellulosic bioethanol production become more efficient and cost effective, plant biomass from any source may be used as a feedstock for bioethanol production. Thus, a move away from using food plants to make fuel is possible, and sources of biomass such as wood from forestry and plant waste from cropping may be used. However, the bioethanol industry will need a continuous and reliable supply of biomass that can be produced at a low cost and with minimal use of water, fertilizer and arable land. As many C4 plants have high light, water and nitrogen use efficiency, as compared with C3 species, they are ideal as feedstock crops. We consider the productivity and resource use of a number of candidate plant species, and discuss biomass ＇quality＇, that is, the composition of the plant cell wall.
基金the project"innovation in Increasing the Organic Carbon in Soil for Sustainable Agricultural Purpose in Saline Soil Areas:First-Year Pilot Project at the Lam Takong Watershed"Ratchadaphisek Somphot Endowment Fund(2014),Chulalongkorn University(CU-57-090-CC).
文摘Lignocellulosic biomass can be circulated to produce many materials and products,including biochar.This study analyzed five different types of biochar produced from agricultural wastes and wood residues.The raw materials included three agricultural by-products:corncob,cassava rhizome,rice husk,and two types of wood residues:rain tree(Samanea saman(Jacq.)Merr.)and krachid(Streblus ilicifolius(Vidal)Corner.).The biochar were made in patented retorts with locally-appropriated technology at a temper-ature range of 450e500C.This research focuses on the primary physicochemical properties and biochar components,allowing biochar to become a vital material to support sustainable agriculture and the environment.Biochar properties used for agriculture consist of specific surface area,total pore volume,average pore diameter,pH,electrical conductivity(EC),and cation exchange capacity(CEC).The prop-erties that benefit the environmental purposes are the element:carbon(C),hydrogen(H),nitrogen(N),oxygen(O),and the molar ratio of H/C,O/C,and C/N.The study found that all five types of biochar contained suitable properties for soil amendment and carbon sequestration.However,significant dif-ferences were shown in specific surface area,average pore diameter,pH,CEC,and EC of various biochar.Based on O/C and H/C ratios,all five types of biochar persisted in soil from 100 to over 1,000 years.
