Nanocellulose composites combine the advantages of nanocellulose and composites. Recently, nanocellulose composites have been received more attentions due to their improved properties and promising broad applications....Nanocellulose composites combine the advantages of nanocellulose and composites. Recently, nanocellulose composites have been received more attentions due to their improved properties and promising broad applications. In the past, rapid progress has been made in the synthesis, properties, and mechanism of nanocellulose composites and potential applications were reported. There are a few reports on the increasing applications of nanocellulose composites with focus on the biomedical field, environmental field, electrode and sensor applications. In this article, the recent development of nanocellulose composites was reviewed via some typical examples. In addition to the synthesis methods, improved properties and potential applications were discussed. The problems and future applications of nanocellulose composites were also suggested.展开更多
Nanocellulose is a biodegradable, renewable, nonmeltable polymeric material that is insoluble in most solvents due to hydrogen bonding and crystallinity. Nanocellulose has attracted considerable attention in recent de...Nanocellulose is a biodegradable, renewable, nonmeltable polymeric material that is insoluble in most solvents due to hydrogen bonding and crystallinity. Nanocellulose has attracted considerable attention in recent decades owing to its environmental friendliness, wide availability, good biocompatibility, high crystallinity, and high Young's modulus. This review presents the recent achievements in preparation and applications of nanocellulose, including a discussion of the advantages and disadvantages of various preparation methods and a summary of the applications of nanocellulose in composite materials research. Finally, we examine the mounting evidence of more widespread potential applications of nanocellulose.展开更多
Cellulose is the most abundant biomass material in nature and it is mainly extracted from natural or lignocellulosic fibers.After purification,cellulose fibers exhibit two interesting features for their further transf...Cellulose is the most abundant biomass material in nature and it is mainly extracted from natural or lignocellulosic fibers.After purification,cellulose fibers exhibit two interesting features for their further transformation into nanomaterials:a hierarchical and multi-level strcture,and a semicrystalline microstructure.Different forms of cellulose nanomaterials,resulting from a top-down deconstructing strategy(cellulose nanocrystals(CNCs),cellulose nanofibrils(CNFs))or bottom-up strategy(bacterial cellulose(BC))can be prepared.Multiple mechanical shearing actions applied to cellulosic fibers release more or less the nanofibrils individually.A controlled strong acid hydrolysis treatment can be applied to cellulosic fibers allowing dissolution of non-crystalline domains.Such cellulose nanomaterials have been the focus of an exponentially increasing number of works or reviews devoted to understand such materials and their applications.They have a high potential for an emerging industry.In the nanoscale,cellulose exhibits specific properties broadening the applications of this naturally occurring polymer.An overview of existing methods for the preparation of cellulose nanomaterials and their specific properties that outperform and contrast with cellulose in the microscale is proposed.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
Paper products such as corrugated paperboards are the most common green packaging materials, which are renewable, sustainable, recyclable and biodegradable. However, the plastic or metal straps used to secure the cart...Paper products such as corrugated paperboards are the most common green packaging materials, which are renewable, sustainable, recyclable and biodegradable. However, the plastic or metal straps used to secure the carton boxes are not so green. At the end of packaging, the carton boxes can be recycled, but the plastic/metal straps have to be sorted out for disposal separately. This review focuses on: 1) the global trend of green packaging;2) conventional plastic/metal strapping materials for carton boxes;3) conventional market pulp baling with steel wire as the tying materials;4) cellulose fiber-based materials for strapping market pulp bales and carton boxes. New generation of cellulose paper straps are being developed for more challenging applications with superior strength properties and repulpability.展开更多
The development of renewable,cost-efficient,and environmentally friendly electrode materials with excellent performance is urgently needed for improving supercapacitors(SCs).Recently,biomass-derived porous carbons(BPC...The development of renewable,cost-efficient,and environmentally friendly electrode materials with excellent performance is urgently needed for improving supercapacitors(SCs).Recently,biomass-derived porous carbons(BPCs)have received increasing attention due to their excellent physical and chemical properties,widespread availability,and low production cost.In this review,the progress in preparing BPCs and the properties of prepared BPCs are presented and discussed.In addition,the applications of BPCs as electrode materials for supercapacitors are also summarized.More importantly,the pore structure and surface properties of BPCs are all determining factors to improve electrochemical performance.Moreover,a high energy density and power density can be pursued by using composites based on BPCs as electrode materials,of which combining transition metallic oxide with BPCs is one of the most attractive selections.Therefore,rational design of BPCs with respect to the supercapacitor's performance should be conducted in the future.展开更多
Cellulose nanocrystals （CNCs） of rod-like shape were prepared from degreased cotton using sulfuric acid hydrolysis. The obtained CNC suspension was neutralized using a sodium hydroxide solution to remove the...Cellulose nanocrystals （CNCs） of rod-like shape were prepared from degreased cotton using sulfuric acid hydrolysis. The obtained CNC suspension was neutralized using a sodium hydroxide solution to remove the residual sulfuric acid and improve the thermal stability of the CNC particles. Then, poly（ethylene oxide） （PEO） was employed to modify the nanocrystals through entanglement and physical adsorption. The goal was to further improve the thermal stability and weaken the hydrophilicity of CNCs. Original and modifed CNCs were dosed into a polylactic acid （PLA） matrix to prepare nanocomposites using a hot compression process. Results of the thermogravimetric analysis showed that the initial thermal decomposition temperature of the modifed CNCs showed a 120℃ improvement compared to the original CNCs. That is, the thermal stability of the modified CNCs improved because of their shielding and wrapping by a PEO layer on their surface. Results from scanning electron microscopy and ultraviolet-visible spectrophotometry showed that the compatibility of the modifed CNCs with organic PLA improved, which was attributed to the compatibility of the PEO chains adsorbed on the surface of the CNCs. Finally, the results of tensile tests indicated a significant improvement in terms of breaking strength and elongation at the break point.展开更多
In this article, a facile two-step activation method, coupled with phosphoric acid(H3PO4)-assisted pretreatment and followed KOH activation,was reported for constructing hierarchical porous carbon(HPC) materials deriv...In this article, a facile two-step activation method, coupled with phosphoric acid(H3PO4)-assisted pretreatment and followed KOH activation,was reported for constructing hierarchical porous carbon(HPC) materials derived from lignin. The introduction of H3PO4, cross-linked with lignin sources generated phosphate(and/or polyphosphate) ester groups throughout the lignin structure, which endowed the pre-activated intermediate char(IC)with a hierarchical porous structure. Such phosphate esters contributed to the multi-scale pore structure within the pre-activated IC, which was beneficial for the uniform distribution and impregnation of subsequent KOH activators,thus leading to the formation of HPC materials. The as-prepared HPC exhibited a large specific surface area(SSA) of 1345.1 m^2/g, which ensures the accessibility of the ion diffusion pathways. The supercapacitors integrated with HPC delivered a high specific capacitance of 241 F/g(in a threeelectrode system) and outstanding rate capability with an 80.9% capacitance retention from 0.5 A/g to an ultra-high current density of 50 A/g.展开更多
Nanocellulose(NC) has attracted much interest in the tissue engineering(TE) field because of its properties including biocompatibility,renewability, non-toxicity, functionality, and excellent mechanical performance. T...Nanocellulose(NC) has attracted much interest in the tissue engineering(TE) field because of its properties including biocompatibility,renewability, non-toxicity, functionality, and excellent mechanical performance. This review mainly focused on the advanced applications of NC-based composites in hard TE including cartilage TE, bone TE, and dental TE, illustrated the processing methods for synthesizing scaffolds including electrospinning, freeze-drying, and 3 D printing, reviewed the current status of hard TE, and presented perspective on the future of TE technology.展开更多
Cellulose is the most abundant organic macromolecule in nature and is renewable,degradable,and biocompatible.The structure of native cellulose has not yet been completely elucidated.Part of cellulose is tightly combin...Cellulose is the most abundant organic macromolecule in nature and is renewable,degradable,and biocompatible.The structure of native cellulose has not yet been completely elucidated.Part of cellulose is tightly combined with lignin macromolecules through chemical bonds to form cellulose-lignin complexes(CLC).The existence of the CLC structure inhibits the complete separation of cellulose from lignocellulosic material,which not only increases the consumption of chemicals in the cooking process and causes environmental pollution,but also makes the cellulose subject to certain degradation during the deep delignification process.Therefore,elucidation of the relationship between the cellulose-lignin connection structure and performance is of great significance for efficient separation of cellulose.This article reviews the current research status of CLC and discusses the research progress regarding its biodegradation characteristics.展开更多
Recently,cellulose nanofibril(CNF)has emerged as a promising,sustainable reinforcement with outstanding potential in material science.Owing to the properties of CNF,it has been explored in food,cosmetic,and pharmaceut...Recently,cellulose nanofibril(CNF)has emerged as a promising,sustainable reinforcement with outstanding potential in material science.Owing to the properties of CNF,it has been explored in food,cosmetic,and pharmaceutical applications,as well as in industrial applications such as paints,drill muds,packaging,and papermaking.The application of CNF in papermaking is expected to be implemented in the near future to broaden the commercial market of cellulose.Numerous studies and patents have reported on the manufacturing,properties,and applications of nanocellulose.This present paper focuses on the recent progresses in the application of CNF as a wet-end additive in papermaking.展开更多
Nanocellulose,a kind of cellulose with nanometer sizes,has drawn great interest in the pulp and paper industry due to its unique structure and excellent performance.It can be divided into five categories:nanocrystalli...Nanocellulose,a kind of cellulose with nanometer sizes,has drawn great interest in the pulp and paper industry due to its unique structure and excellent performance.It can be divided into five categories:nanocrystalline cellulose(NCC),nanofibrillated cellulose(NFC),bacterial cellulose(BC),electrospun cellulose nanofibers(ESC),and precipitation regenerated cellulose nanofibers(PRC).In this paper,we reviewed the industrialization progress of nanocellulose in China.Furthermore,we proposed that efficient and environmentally friendly preparation methods and high value utilization would be the focus of nanocellulose development.展开更多
To improve the performance of polyurethane films,small amounts of cellulose nanofibrils(CNF)were physically blended with a waterborne polyurethane(WPU)emulsion,and then CNF/WPU composite films were prepared by cast-co...To improve the performance of polyurethane films,small amounts of cellulose nanofibrils(CNF)were physically blended with a waterborne polyurethane(WPU)emulsion,and then CNF/WPU composite films were prepared by cast-coating and drying.The particle size of the emulsions and the chemical structure,micromorphology,thermal stability,mechanical properties,and water resistance of the composite films were characterized using a Malvern laser particle size analyzer,Fourier transform infrared spectroscopy(FT-IR),scanning electron microscopy(SEM),thermogravimetric analysis(TGA),an electronic strength machine,water contact angle analysis(WCA),and water absorption tests,respectively.The results showed that at a low CNF content of 0.3 wt%,the particle size of the WPU emulsion and chemical structure of the film did not change significantly.In addition,the tensile strength of the composite film increased by up to 108%compared to the neat WPU film,and the thermal stability and water resistance were slightly improved.The addition of CNF greatly enhanced the tensile strength while maintaining the other original properties of the WPU film,which may greatly improve the service life and tear resistance of commercial coatings in the future.展开更多
Green, biodegradable, and eco-friendly interface materials based on cellulose and its derivatives were prepared for organic solar cells(OSCs). In this work, calcium and two derivatives of cellulose with different carb...Green, biodegradable, and eco-friendly interface materials based on cellulose and its derivatives were prepared for organic solar cells(OSCs). In this work, calcium and two derivatives of cellulose with different carboxy acid groups, denoted as Cellulose-COOH and Cellulose-(COOH)n, were used as cathode interfacial layers of OSCs, and a blend of the low-band-gap semiconducting polymers thieno[3, 4-b]thiophene/benzodithiophene(PTB7)and [6, 6]-phenyl C71-butyric acid methyl ester(PC71BM) was chosen as the photoactive layer. OSCs were fabricated with a configuration of indiumdoped tin oxide(ITO)/poly(3, 4-ethylenedioxythiophene) : polystyrene sulfonate(PEDOT: PSS)/PTB7: PC71BM/Ca or Cellulose-COOH or Cellulose-(COOH)n/Al. As a result, the effect of cellulose-COOH was the best one among them, and the power conversion efficiency(PCE) reached 8.21%for the devices with cathode interfacial layer of Cellulose-COOH, which was better than that of OSCs using calcium as a modifier(PCE=7.95%). The favorable performance is attributed to the reduced work function and improved electron transfer caused by the introduction of carboxy cellulose between the active layer and the electrode. The developed technology shows great potential in accelerating the diversified applications of cellulose and producing cost-effective and eco-friendly interfaces for OSCs.展开更多
Nanocelluloses, obtained from the biopolymer cellulose, are a class of renewable functional nanomaterials with excellent properties and a broad range of applications. This review mainly illustrates practical and advan...Nanocelluloses, obtained from the biopolymer cellulose, are a class of renewable functional nanomaterials with excellent properties and a broad range of applications. This review mainly illustrates practical and advanced applications of nanocellulose-based materials in the following categories.(1) Fire-resistant materials: in the section on these types of materials, the fireprotection property of nanocellulose/clay hybrid composites(clay nanopaper) is illustrated; oriented montmorillonite(MTM) provides barrier properties and low thermal conductivity whereas cellulose nanofibers(CNFs) impart favorable charring.(2) Thermal insulation materials: the best way to obtain materials with good heat insulation performance is to decrease the thermal conductivity of such materials.(3) Template materials: nanocellulose can direct the deposition and patterning of materials to form nanoparticles, nanowires, or nanotubes with improved properties.展开更多
In this study, soybean residues were treated with HCl and soybean residue cellulose was extracted, which was used to prepare cellulose nanofiber (CNF) using the high-pressure homogenization method. The maximum yield o...In this study, soybean residues were treated with HCl and soybean residue cellulose was extracted, which was used to prepare cellulose nanofiber (CNF) using the high-pressure homogenization method. The maximum yield of CNF, the reaction temperature, reaction time, and HCl concentration were optimized. The optimum HCl concentration for acid treatment was 6%, the reaction time was 60 min, the reaction temperature was 80℃, and the maximum yield of soybean residue cellulose was 78.8%. The different CNF films were then prepared;the color, mechanical property, and light transmittance of the CNF films were studied. Compared to the properties of the CNF film prepared with the soybean residue cellulose by high-pressure homogenization 15 times (HGT-15 film), the mechanical properties of the CNF film with soybean residue cellulose by decolorizing treatment decreased, but the light transmittance increased. The film prepared by adding HGT- 15 CNF to whey protein was investigated for its mechanical property, light transmittance, and solubility. Unlike the pure whey protein film, addition of 2.0% CNF to the whey protein enhanced the mechanical property and water vapor transmission rate (WVT) of the film. With the increase in CNF content, the solubility of the whey protein film decreased, and then stabilized.展开更多
Lignin is the most abundant aromatic compound found in nature.The rich functional groups of lignin are responsible for its antibacterial,antioxidant,anti-ultraviolet,and biocompatible properties.As modified lignin has...Lignin is the most abundant aromatic compound found in nature.The rich functional groups of lignin are responsible for its antibacterial,antioxidant,anti-ultraviolet,and biocompatible properties.As modified lignin has a higher molecular weight,water solubility,and better surface activity,it is a good candidate for the construction of new biological materials.Ligninbased hydrogels are a type of functional materials with broad application prospects in the biomedical field.This review aimed to introduce the biological properties of lignin and the application of lignin-based hydrogels in the biological field.展开更多
The basis weight control loop of the papermaking process is a non-linear system with time-delay and time-varying.It is impractical to identify a model that can restore the model of real papermaking process.Determining...The basis weight control loop of the papermaking process is a non-linear system with time-delay and time-varying.It is impractical to identify a model that can restore the model of real papermaking process.Determining a more accurate identification model is very important for designing the controller of the control system and maintaining the stable operation of the papermaking process.In this study,a strange nonchaotic particle swarm optimization(SNPSO)algorithm is proposed to identify the models of real papermaking processes,and this identification ability is significantly enhanced compared with particle swarm optimization(PSO).First,random particles are initialized by strange nonchaotic sequences to obtain high-quality solutions.Furthermore,the weight of linear attenuation is replaced by strange nonchaotic sequence and the time-varying acceleration coefficients and a mutation rule with strange nonchaotic characteristics are utilized in SNPSO.The above strategies effectively improve the global and local search ability of particles and the ability to escape from local optimization.To illustrate the effectiveness of SNPSO,step response data are used to identify the models of real industrial processes.Compared with classical PSO,PSO with timevarying acceleration coefficients(PSO-TVAC)and modified particle swarm optimization(MPSO),the simulation results demonstrate that SNPSO has stronger identification ability,faster convergence speed,and better robustness.展开更多
The purpose of this study was to explore the differences of the hemicelluloses extracted by hydrothermal pretreatment using water and alkaline solutions(Na OH or KOH). The physicochemical properties and structural cha...The purpose of this study was to explore the differences of the hemicelluloses extracted by hydrothermal pretreatment using water and alkaline solutions(Na OH or KOH). The physicochemical properties and structural characteristics of two water-soluble and four alkali-soluble hemicelluloses extracted from the triploid of Populus tomentosa Carr. through the hydrothermal pretreatment were comparatively studied. It was observed that the alkalis(Na OH and KOH) were more effective than distilled water as extractants. Sugar analysis showed that xylose(66.83%~86.49%) was the major constituent, followed by glucose(6.83%~18.49%). Mannose(1.40%~8.42%), galactose(2.17%~4.05%), and arabinose(0.21%~2.26%) were also detected in the hemicellulosic fractions. The results of gelpermeation chromatography(GPC) indicated that the hemicelluloses extracted using the alkaline solutions had relatively higher molecular weights than those solubilized in distilled water. Further, based on spectroscopic ~1Hnuclear magnetic resonance(~1H-NMR) and two-dimensional heteronuclear singular quantum correlation(2D-HSQC) analyses, it was confirmed that the hemicellulosic fractions had a major structure of(1→4)-b-D-xylan and a minor structure of(1→4)-a-D-glucan with small amounts of substituted sugars and glucuronic acid attached.展开更多
Functional composite films were successfully prepared from cellulose, graphite(GP), and polyaniline(PANI) using a combination of physical and chemical processes. Cellulosewasdissolved in N-methylmorpholine-N-oxide mon...Functional composite films were successfully prepared from cellulose, graphite(GP), and polyaniline(PANI) using a combination of physical and chemical processes. Cellulosewasdissolved in N-methylmorpholine-N-oxide monohydrate(NMMO) and regenerated in water to form the matrix. GP was dispersed in the NMMO solvent prior to the dissolution of the cellulose, and PANI was deposited on the surfaces of the cellulose/GP films by in situ chemical polymerization. The structures of the PANI/cellusose/GP composite films were investigated using X-ray diffraction analysis, Fourier transform infrared spectroscopy, scanning electron microscopy(SEM), and SEM/energy-dispersive X-ray spectroscopy. The mechanical strengths, thermal stabilities, conductivities, and antibacterial activities of the films were studied in detail. The results showed that GP formed a multilayered structure in the cellulose matrix and that the PANI nanoparticles were tightly wrapped on the film surface. The film thickness increased from 40 mm to 100 mm after the addition of GP and PANI. The tensile strength of the composite films was 80~107 MPa, with the elongation at break being 3%~10%. The final residual weight of the composite films was as high as 65%, and the conductivity of the composite films reached 14.36 S/m. The cellulose matrix ensured that the films were flexible and exhibited desirable mechanical properties, while the GP filler significantly improved the thermal stability of the films. The PANI coating acted as a protective layer during burning and provided good electrical conductivity and antibacterial activity against Escherichia coli; both of these characteristics were slightly enhanced by the incorporation of GP. These PANI/cellulose/GP composite films should be suitable for use in electronics, antistatic packing, and numerous other applications.展开更多
基金Financial supported from the Fundamental Research Funds for the Central Universities (No. 2017ZY49)the Foundation (No. KF201607) of Key Laboratory of Pulp and Paper Science and Technology of Ministry of Education/Shandong Province of China
文摘Nanocellulose composites combine the advantages of nanocellulose and composites. Recently, nanocellulose composites have been received more attentions due to their improved properties and promising broad applications. In the past, rapid progress has been made in the synthesis, properties, and mechanism of nanocellulose composites and potential applications were reported. There are a few reports on the increasing applications of nanocellulose composites with focus on the biomedical field, environmental field, electrode and sensor applications. In this article, the recent development of nanocellulose composites was reviewed via some typical examples. In addition to the synthesis methods, improved properties and potential applications were discussed. The problems and future applications of nanocellulose composites were also suggested.
基金financially supported by the National Natural Science Foundation of China(51603050)the Natural Science Foundation of Guangxi Autonomous Region(2016GXNSFBA380064,2016GXNSFAA380029)+1 种基金the Startup Foundation for Doctors of Guilin University of Technologythe Open Project Foundation of the Guangxi Key Laboratory of New Energy and Building Energy Saving(16-J-21-3)
文摘Nanocellulose is a biodegradable, renewable, nonmeltable polymeric material that is insoluble in most solvents due to hydrogen bonding and crystallinity. Nanocellulose has attracted considerable attention in recent decades owing to its environmental friendliness, wide availability, good biocompatibility, high crystallinity, and high Young's modulus. This review presents the recent achievements in preparation and applications of nanocellulose, including a discussion of the advantages and disadvantages of various preparation methods and a summary of the applications of nanocellulose in composite materials research. Finally, we examine the mounting evidence of more widespread potential applications of nanocellulose.
基金LGP2 is part of the LabEx Tec 21(Investissements d’Avenir-grant agreement n°ANR-11-LABX-0030)of the PolyNat Carnot Institut(Investissements d’Avenir-grant agreement n°ANR-11-CARN-030-01).
文摘Cellulose is the most abundant biomass material in nature and it is mainly extracted from natural or lignocellulosic fibers.After purification,cellulose fibers exhibit two interesting features for their further transformation into nanomaterials:a hierarchical and multi-level strcture,and a semicrystalline microstructure.Different forms of cellulose nanomaterials,resulting from a top-down deconstructing strategy(cellulose nanocrystals(CNCs),cellulose nanofibrils(CNFs))or bottom-up strategy(bacterial cellulose(BC))can be prepared.Multiple mechanical shearing actions applied to cellulosic fibers release more or less the nanofibrils individually.A controlled strong acid hydrolysis treatment can be applied to cellulosic fibers allowing dissolution of non-crystalline domains.Such cellulose nanomaterials have been the focus of an exponentially increasing number of works or reviews devoted to understand such materials and their applications.They have a high potential for an emerging industry.In the nanoscale,cellulose exhibits specific properties broadening the applications of this naturally occurring polymer.An overview of existing methods for the preparation of cellulose nanomaterials and their specific properties that outperform and contrast with cellulose in the microscale is proposed.
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Paper products such as corrugated paperboards are the most common green packaging materials, which are renewable, sustainable, recyclable and biodegradable. However, the plastic or metal straps used to secure the carton boxes are not so green. At the end of packaging, the carton boxes can be recycled, but the plastic/metal straps have to be sorted out for disposal separately. This review focuses on: 1) the global trend of green packaging;2) conventional plastic/metal strapping materials for carton boxes;3) conventional market pulp baling with steel wire as the tying materials;4) cellulose fiber-based materials for strapping market pulp bales and carton boxes. New generation of cellulose paper straps are being developed for more challenging applications with superior strength properties and repulpability.
基金grateful for the financial support from the National Key Research and Development Plan(Grant No.2017YFB0307901).
文摘The development of renewable,cost-efficient,and environmentally friendly electrode materials with excellent performance is urgently needed for improving supercapacitors(SCs).Recently,biomass-derived porous carbons(BPCs)have received increasing attention due to their excellent physical and chemical properties,widespread availability,and low production cost.In this review,the progress in preparing BPCs and the properties of prepared BPCs are presented and discussed.In addition,the applications of BPCs as electrode materials for supercapacitors are also summarized.More importantly,the pore structure and surface properties of BPCs are all determining factors to improve electrochemical performance.Moreover,a high energy density and power density can be pursued by using composites based on BPCs as electrode materials,of which combining transition metallic oxide with BPCs is one of the most attractive selections.Therefore,rational design of BPCs with respect to the supercapacitor's performance should be conducted in the future.
基金the National Natural Science Foundation of China (grant Nos. 31570578 and 31270632)the Fundamental Research Funds for the Central Universities (grant No. JUSRP51622A)the State Key Laboratory of Pulp and Paper Engineering (grant No. 201809)
文摘Cellulose nanocrystals （CNCs） of rod-like shape were prepared from degreased cotton using sulfuric acid hydrolysis. The obtained CNC suspension was neutralized using a sodium hydroxide solution to remove the residual sulfuric acid and improve the thermal stability of the CNC particles. Then, poly（ethylene oxide） （PEO） was employed to modify the nanocrystals through entanglement and physical adsorption. The goal was to further improve the thermal stability and weaken the hydrophilicity of CNCs. Original and modifed CNCs were dosed into a polylactic acid （PLA） matrix to prepare nanocomposites using a hot compression process. Results of the thermogravimetric analysis showed that the initial thermal decomposition temperature of the modifed CNCs showed a 120℃ improvement compared to the original CNCs. That is, the thermal stability of the modified CNCs improved because of their shielding and wrapping by a PEO layer on their surface. Results from scanning electron microscopy and ultraviolet-visible spectrophotometry showed that the compatibility of the modifed CNCs with organic PLA improved, which was attributed to the compatibility of the PEO chains adsorbed on the surface of the CNCs. Finally, the results of tensile tests indicated a significant improvement in terms of breaking strength and elongation at the break point.
基金supported by the Fundamental Research Funds for the Central Universities(BLX201823)Beijing Forestry University Outstanding Young Talent Cultivation Project(2019JQ03017)Beijing Municipal Natural Science Foundation(6182031).
文摘In this article, a facile two-step activation method, coupled with phosphoric acid(H3PO4)-assisted pretreatment and followed KOH activation,was reported for constructing hierarchical porous carbon(HPC) materials derived from lignin. The introduction of H3PO4, cross-linked with lignin sources generated phosphate(and/or polyphosphate) ester groups throughout the lignin structure, which endowed the pre-activated intermediate char(IC)with a hierarchical porous structure. Such phosphate esters contributed to the multi-scale pore structure within the pre-activated IC, which was beneficial for the uniform distribution and impregnation of subsequent KOH activators,thus leading to the formation of HPC materials. The as-prepared HPC exhibited a large specific surface area(SSA) of 1345.1 m^2/g, which ensures the accessibility of the ion diffusion pathways. The supercapacitors integrated with HPC delivered a high specific capacitance of 241 F/g(in a threeelectrode system) and outstanding rate capability with an 80.9% capacitance retention from 0.5 A/g to an ultra-high current density of 50 A/g.
基金the special fund for Independent Innovation and Industry Development in the Core Area in Haidian District of Beijing (255-kjc020)
文摘Nanocellulose(NC) has attracted much interest in the tissue engineering(TE) field because of its properties including biocompatibility,renewability, non-toxicity, functionality, and excellent mechanical performance. This review mainly focused on the advanced applications of NC-based composites in hard TE including cartilage TE, bone TE, and dental TE, illustrated the processing methods for synthesizing scaffolds including electrospinning, freeze-drying, and 3 D printing, reviewed the current status of hard TE, and presented perspective on the future of TE technology.
基金The authors are grateful for the support of the National Natural Science Foundation of China(No.21878070)Hubei Provincial Universities Outstanding Young and Middle-aged Technological Innovation Team Project(No.T201205).
文摘Cellulose is the most abundant organic macromolecule in nature and is renewable,degradable,and biocompatible.The structure of native cellulose has not yet been completely elucidated.Part of cellulose is tightly combined with lignin macromolecules through chemical bonds to form cellulose-lignin complexes(CLC).The existence of the CLC structure inhibits the complete separation of cellulose from lignocellulosic material,which not only increases the consumption of chemicals in the cooking process and causes environmental pollution,but also makes the cellulose subject to certain degradation during the deep delignification process.Therefore,elucidation of the relationship between the cellulose-lignin connection structure and performance is of great significance for efficient separation of cellulose.This article reviews the current research status of CLC and discusses the research progress regarding its biodegradation characteristics.
基金grateful for the financial support from the National Natural Science Foundation of China(Grant Nos.31770628 and 31901267)the Taishan Scholars Program+3 种基金the Provincial Key Research and Development Program of Shandong(Grant Nos.2019JZZY010326 and 2019JZZY010328)a projectu(Grant No.ZR2019BC042)supported by the Shandong Provincial Natural Science Foundationa project of the Shandong Province Higher Educational Science and Technology Program(J18KA111).
文摘Recently,cellulose nanofibril(CNF)has emerged as a promising,sustainable reinforcement with outstanding potential in material science.Owing to the properties of CNF,it has been explored in food,cosmetic,and pharmaceutical applications,as well as in industrial applications such as paints,drill muds,packaging,and papermaking.The application of CNF in papermaking is expected to be implemented in the near future to broaden the commercial market of cellulose.Numerous studies and patents have reported on the manufacturing,properties,and applications of nanocellulose.This present paper focuses on the recent progresses in the application of CNF as a wet-end additive in papermaking.
基金the financial support from the National Natural Science Foundation of China(21875050)
文摘Nanocellulose,a kind of cellulose with nanometer sizes,has drawn great interest in the pulp and paper industry due to its unique structure and excellent performance.It can be divided into five categories:nanocrystalline cellulose(NCC),nanofibrillated cellulose(NFC),bacterial cellulose(BC),electrospun cellulose nanofibers(ESC),and precipitation regenerated cellulose nanofibers(PRC).In this paper,we reviewed the industrialization progress of nanocellulose in China.Furthermore,we proposed that efficient and environmentally friendly preparation methods and high value utilization would be the focus of nanocellulose development.
文摘To improve the performance of polyurethane films,small amounts of cellulose nanofibrils(CNF)were physically blended with a waterborne polyurethane(WPU)emulsion,and then CNF/WPU composite films were prepared by cast-coating and drying.The particle size of the emulsions and the chemical structure,micromorphology,thermal stability,mechanical properties,and water resistance of the composite films were characterized using a Malvern laser particle size analyzer,Fourier transform infrared spectroscopy(FT-IR),scanning electron microscopy(SEM),thermogravimetric analysis(TGA),an electronic strength machine,water contact angle analysis(WCA),and water absorption tests,respectively.The results showed that at a low CNF content of 0.3 wt%,the particle size of the WPU emulsion and chemical structure of the film did not change significantly.In addition,the tensile strength of the composite film increased by up to 108%compared to the neat WPU film,and the thermal stability and water resistance were slightly improved.The addition of CNF greatly enhanced the tensile strength while maintaining the other original properties of the WPU film,which may greatly improve the service life and tear resistance of commercial coatings in the future.
基金financially supported by the National Natural Science Foundation of China(21674123,31700520)National Natural Science Foundation of Fujian Province(2018J01592)+1 种基金Project of “100 People Planning in Fujian Province”,New Century Excellent Talents in Fujian Province University(KLa17009A)International Cooperation Project of Fujian Agriculture and Forestry University(KXGH17003).
文摘Green, biodegradable, and eco-friendly interface materials based on cellulose and its derivatives were prepared for organic solar cells(OSCs). In this work, calcium and two derivatives of cellulose with different carboxy acid groups, denoted as Cellulose-COOH and Cellulose-(COOH)n, were used as cathode interfacial layers of OSCs, and a blend of the low-band-gap semiconducting polymers thieno[3, 4-b]thiophene/benzodithiophene(PTB7)and [6, 6]-phenyl C71-butyric acid methyl ester(PC71BM) was chosen as the photoactive layer. OSCs were fabricated with a configuration of indiumdoped tin oxide(ITO)/poly(3, 4-ethylenedioxythiophene) : polystyrene sulfonate(PEDOT: PSS)/PTB7: PC71BM/Ca or Cellulose-COOH or Cellulose-(COOH)n/Al. As a result, the effect of cellulose-COOH was the best one among them, and the power conversion efficiency(PCE) reached 8.21%for the devices with cathode interfacial layer of Cellulose-COOH, which was better than that of OSCs using calcium as a modifier(PCE=7.95%). The favorable performance is attributed to the reduced work function and improved electron transfer caused by the introduction of carboxy cellulose between the active layer and the electrode. The developed technology shows great potential in accelerating the diversified applications of cellulose and producing cost-effective and eco-friendly interfaces for OSCs.
文摘Nanocelluloses, obtained from the biopolymer cellulose, are a class of renewable functional nanomaterials with excellent properties and a broad range of applications. This review mainly illustrates practical and advanced applications of nanocellulose-based materials in the following categories.(1) Fire-resistant materials: in the section on these types of materials, the fireprotection property of nanocellulose/clay hybrid composites(clay nanopaper) is illustrated; oriented montmorillonite(MTM) provides barrier properties and low thermal conductivity whereas cellulose nanofibers(CNFs) impart favorable charring.(2) Thermal insulation materials: the best way to obtain materials with good heat insulation performance is to decrease the thermal conductivity of such materials.(3) Template materials: nanocellulose can direct the deposition and patterning of materials to form nanoparticles, nanowires, or nanotubes with improved properties.
基金supported by the foundation of State Key Laboratory of Pulp and Paper Engineering (201819)the project of Shaanxi Provincial Department of Education Key Laboratory Research Open Fund (Grant No. 17JS017)the project of Shaanxi University of Science and Technology Research Initial Fund (Grant No. BJ15-29)
文摘In this study, soybean residues were treated with HCl and soybean residue cellulose was extracted, which was used to prepare cellulose nanofiber (CNF) using the high-pressure homogenization method. The maximum yield of CNF, the reaction temperature, reaction time, and HCl concentration were optimized. The optimum HCl concentration for acid treatment was 6%, the reaction time was 60 min, the reaction temperature was 80℃, and the maximum yield of soybean residue cellulose was 78.8%. The different CNF films were then prepared;the color, mechanical property, and light transmittance of the CNF films were studied. Compared to the properties of the CNF film prepared with the soybean residue cellulose by high-pressure homogenization 15 times (HGT-15 film), the mechanical properties of the CNF film with soybean residue cellulose by decolorizing treatment decreased, but the light transmittance increased. The film prepared by adding HGT- 15 CNF to whey protein was investigated for its mechanical property, light transmittance, and solubility. Unlike the pure whey protein film, addition of 2.0% CNF to the whey protein enhanced the mechanical property and water vapor transmission rate (WVT) of the film. With the increase in CNF content, the solubility of the whey protein film decreased, and then stabilized.
基金the financial support from the National Natural Science Foundation of China(32171717)the Young Elite Scientists Sponsorship Program(YESS20200389).
文摘Lignin is the most abundant aromatic compound found in nature.The rich functional groups of lignin are responsible for its antibacterial,antioxidant,anti-ultraviolet,and biocompatible properties.As modified lignin has a higher molecular weight,water solubility,and better surface activity,it is a good candidate for the construction of new biological materials.Ligninbased hydrogels are a type of functional materials with broad application prospects in the biomedical field.This review aimed to introduce the biological properties of lignin and the application of lignin-based hydrogels in the biological field.
基金support received from the National Natural Science Foundation of China(Grant No.62073206)Technical Innovation Guidance Project of Shaanxi Province(Grant No.2020CGHJ-007).
文摘The basis weight control loop of the papermaking process is a non-linear system with time-delay and time-varying.It is impractical to identify a model that can restore the model of real papermaking process.Determining a more accurate identification model is very important for designing the controller of the control system and maintaining the stable operation of the papermaking process.In this study,a strange nonchaotic particle swarm optimization(SNPSO)algorithm is proposed to identify the models of real papermaking processes,and this identification ability is significantly enhanced compared with particle swarm optimization(PSO).First,random particles are initialized by strange nonchaotic sequences to obtain high-quality solutions.Furthermore,the weight of linear attenuation is replaced by strange nonchaotic sequence and the time-varying acceleration coefficients and a mutation rule with strange nonchaotic characteristics are utilized in SNPSO.The above strategies effectively improve the global and local search ability of particles and the ability to escape from local optimization.To illustrate the effectiveness of SNPSO,step response data are used to identify the models of real industrial processes.Compared with classical PSO,PSO with timevarying acceleration coefficients(PSO-TVAC)and modified particle swarm optimization(MPSO),the simulation results demonstrate that SNPSO has stronger identification ability,faster convergence speed,and better robustness.
基金financial support from the Fundamental Research Funds for the Central Universities(No.JC2013-3,BLYJ201616)Beijing Higher Education Young Elite Teacher Project(No.YETP0763)
文摘The purpose of this study was to explore the differences of the hemicelluloses extracted by hydrothermal pretreatment using water and alkaline solutions(Na OH or KOH). The physicochemical properties and structural characteristics of two water-soluble and four alkali-soluble hemicelluloses extracted from the triploid of Populus tomentosa Carr. through the hydrothermal pretreatment were comparatively studied. It was observed that the alkalis(Na OH and KOH) were more effective than distilled water as extractants. Sugar analysis showed that xylose(66.83%~86.49%) was the major constituent, followed by glucose(6.83%~18.49%). Mannose(1.40%~8.42%), galactose(2.17%~4.05%), and arabinose(0.21%~2.26%) were also detected in the hemicellulosic fractions. The results of gelpermeation chromatography(GPC) indicated that the hemicelluloses extracted using the alkaline solutions had relatively higher molecular weights than those solubilized in distilled water. Further, based on spectroscopic ~1Hnuclear magnetic resonance(~1H-NMR) and two-dimensional heteronuclear singular quantum correlation(2D-HSQC) analyses, it was confirmed that the hemicellulosic fractions had a major structure of(1→4)-b-D-xylan and a minor structure of(1→4)-a-D-glucan with small amounts of substituted sugars and glucuronic acid attached.
基金financial support from the International S&T Cooperation Program of China (No.2015DFG31860)the National Science Foundation of China for the Key Projects (Nos.31430092 and 31110103902)
文摘Functional composite films were successfully prepared from cellulose, graphite(GP), and polyaniline(PANI) using a combination of physical and chemical processes. Cellulosewasdissolved in N-methylmorpholine-N-oxide monohydrate(NMMO) and regenerated in water to form the matrix. GP was dispersed in the NMMO solvent prior to the dissolution of the cellulose, and PANI was deposited on the surfaces of the cellulose/GP films by in situ chemical polymerization. The structures of the PANI/cellusose/GP composite films were investigated using X-ray diffraction analysis, Fourier transform infrared spectroscopy, scanning electron microscopy(SEM), and SEM/energy-dispersive X-ray spectroscopy. The mechanical strengths, thermal stabilities, conductivities, and antibacterial activities of the films were studied in detail. The results showed that GP formed a multilayered structure in the cellulose matrix and that the PANI nanoparticles were tightly wrapped on the film surface. The film thickness increased from 40 mm to 100 mm after the addition of GP and PANI. The tensile strength of the composite films was 80~107 MPa, with the elongation at break being 3%~10%. The final residual weight of the composite films was as high as 65%, and the conductivity of the composite films reached 14.36 S/m. The cellulose matrix ensured that the films were flexible and exhibited desirable mechanical properties, while the GP filler significantly improved the thermal stability of the films. The PANI coating acted as a protective layer during burning and provided good electrical conductivity and antibacterial activity against Escherichia coli; both of these characteristics were slightly enhanced by the incorporation of GP. These PANI/cellulose/GP composite films should be suitable for use in electronics, antistatic packing, and numerous other applications.
