Chitin is a kind of natural macromolecule material which was first discovered in mushrooms and was widely found in the shells of crustaceans and arthropods,the cell walls of fungi(yeast and mold)and algae,and the moll...Chitin is a kind of natural macromolecule material which was first discovered in mushrooms and was widely found in the shells of crustaceans and arthropods,the cell walls of fungi(yeast and mold)and algae,and the mollusks.The original chitin in nature usually has an antiparallel molecular chain alignment forming nanofibers connected by inter-and intramolecular hydrogen bonds.These microfibers consist of nanofibers about 2-5 nm in diameter,and about 300 nm long,embedded by protein matrices.Due to their unique dimensional,optical,mechanical,and other characteristics,the preparation of nano-chitin materials is an important subject.It is possible to extract nano-chitins from their sources with various methods,including acid hydrolysis,mechanical disintegration,TEMPO-mediated oxidation,electrospinning,and others.In this article,the latest progress in recent years in the preparation and applications of nano-chitin were reviewed.The morphology of the nano-chitins obtained from the above methods was presented.The advantages and disadvantages of each method were analyzed.An overview of applications of nano-chitins was discussed,including biomedicine,food applications,water treatment,green electronic materials,enzyme immobilization carriers,cotton textile materials,cosmetics,and others.展开更多
Cellulose,lignin and lignocellulose are important bioresources in the nature.Their effective and environmentally friendly utilization not only reduces dependence on fossil resources but also protects the environment.R...Cellulose,lignin and lignocellulose are important bioresources in the nature.Their effective and environmentally friendly utilization not only reduces dependence on fossil resources but also protects the environment.Recently,a class of novel eco-friendly solvents,ionic liquids,is employed to dissolve and process these bioresources.In this mini-review,we summarized the recent advances of processing and valorization of cellulose,lignin and lignocellulose in ionic liquids.It is expected that this up-to-date survey provides a comprehensive information of this field,and accelerates the development and utilization of the renewable plant biomass resources.展开更多
Thermal degradation of vegetable-tanned leather fiber(VLF)was investigated by thermogravimetric analysis aiming to know the exact kinetics and degradation mechanism.The thermogravimetric(TG)and differential thermograv...Thermal degradation of vegetable-tanned leather fiber(VLF)was investigated by thermogravimetric analysis aiming to know the exact kinetics and degradation mechanism.The thermogravimetric(TG)and differential thermogravimetric(DTG)curves showed that decomposition of the VLF occurs mainly in the range of 150-600℃,and the latter exhibits asymmetrical peak with a pronounced shoulder.The decomposition process was first analyzed by deconvolution of the experimental DTG curves,followed by reconstruction of the weight loss profiles of two individual processes.Several common isoconversional approaches were applied to calculate the activation energy over a wide range of conversion for the sample,including modified Kissinger-Akahira-Sunose(MKAS),Friedman,and Flynn-Wall-Ozawa.The average activation energy of vegetable-tanned leather fiber was found to be 241.9 kJ mol^(−1) by MKAS method.The activation energy values obtained for the pseudocomponents representing highly-crosslinked and low-crosslinked collagen in VLF were given as 190.6 and 124.8 kJ mol^(−1),respectively.Generalized master plots results suggested that the reaction mechanism for highly-crosslinked collagen follows the random nucleation and growth process at conversion values lower than 0.5.When the conversion is higher than 0.5,the mechanism tends to random scission model.For low-crosslinked collagen,the degradation is mainly governed by random nucleation and nuclei growth.The gaseous products of VLF thermal degradation were analyzed with an online-coupled TG-Fourier transform infrared spectroscopy system.展开更多
Leather is a collagen-based biomass prepared from raw skins or hides by a series of unit operations, in which the unhairing and fiber opening are extremely important operations. However, the conventional Na2S/Ca(OH)2 ...Leather is a collagen-based biomass prepared from raw skins or hides by a series of unit operations, in which the unhairing and fiber opening are extremely important operations. However, the conventional Na2S/Ca(OH)2 system used in unhairing and fiber opening has given rise to the pollution to the environment. It is necessary to develop substitute technology for the Na2S/Ca(OH)2. In the present study, 1-allyl-3-methylimidazolium chloride ([AMIm]Cl) was used to cooperate with dispase for cycle unhairing and one-pot beamhouse to recycle waste bovine hides and com-pared with conventional processing. During those processes, the mechanism of [AMIm]Cl-dispase synergistic unhair-ing and collagen fibers opening were studied. Besides, plant hazard, organic matter and [AMIm]Cl of wastewater from [AMIm]Cl-dispase process were respectively investigated and separated to evaluate the environmental and economic benefits of the [AMIm]Cl-dispase process. As a result, enzyme activity after unhairing by [AMIm]Cl-diapase system for using 5 times is higher than that by KCl-dispase system, and needs lower unhairing time, which is because of rapid penetration of [AMIm]Cl-dispase solution in bovine hides. For this reason, the tensile strength and elastic modulus of tanned leather from [AMIm]Cl-dispase process are higher than those from the KCl-diapase and conventional pro-cesses, and its hydrothermal shrinkage temperature is comparable to that of the conventional one. Because of the 58.13% lower wastewater discharge (WD), 66.60% lower total solids (TS), 97.23% lower ammonia nitrogen (NH3-N), non-toxic wastewater and organic matter recovery in wastewater are reached from [AMIm]Cl-dispase process, which is expected to be an alternative to the conventional process to reduce environmental pollution and realize the sustainable development of technology for leather manufacturing.展开更多
基金supported by the National Natural Science Foundation of China[51473150,51603191,U1404509]sthe Education Department of Henan Province[17HASTIT009]
文摘Chitin is a kind of natural macromolecule material which was first discovered in mushrooms and was widely found in the shells of crustaceans and arthropods,the cell walls of fungi(yeast and mold)and algae,and the mollusks.The original chitin in nature usually has an antiparallel molecular chain alignment forming nanofibers connected by inter-and intramolecular hydrogen bonds.These microfibers consist of nanofibers about 2-5 nm in diameter,and about 300 nm long,embedded by protein matrices.Due to their unique dimensional,optical,mechanical,and other characteristics,the preparation of nano-chitin materials is an important subject.It is possible to extract nano-chitins from their sources with various methods,including acid hydrolysis,mechanical disintegration,TEMPO-mediated oxidation,electrospinning,and others.In this article,the latest progress in recent years in the preparation and applications of nano-chitin were reviewed.The morphology of the nano-chitins obtained from the above methods was presented.The advantages and disadvantages of each method were analyzed.An overview of applications of nano-chitins was discussed,including biomedicine,food applications,water treatment,green electronic materials,enzyme immobilization carriers,cotton textile materials,cosmetics,and others.
基金This work was supported by Beijing Municipal Science&Technology Commission(No.Z191100007219009)Key Programs of the Chinese Academy of Sciences(No.ZDRW-CN-2018-2)+1 种基金National Natural Science Foundation of China(No.51773210)Youth Innovation Promotion Association of Chinese Academy of Sciences(No.2018040).
文摘Cellulose,lignin and lignocellulose are important bioresources in the nature.Their effective and environmentally friendly utilization not only reduces dependence on fossil resources but also protects the environment.Recently,a class of novel eco-friendly solvents,ionic liquids,is employed to dissolve and process these bioresources.In this mini-review,we summarized the recent advances of processing and valorization of cellulose,lignin and lignocellulose in ionic liquids.It is expected that this up-to-date survey provides a comprehensive information of this field,and accelerates the development and utilization of the renewable plant biomass resources.
基金National Key Research and Development Program(2017YFB0308500)National Natural Science Foundation Commission of China(51673177,U1204504)Science and Technology Project of Henan Province(172102410022).
文摘Thermal degradation of vegetable-tanned leather fiber(VLF)was investigated by thermogravimetric analysis aiming to know the exact kinetics and degradation mechanism.The thermogravimetric(TG)and differential thermogravimetric(DTG)curves showed that decomposition of the VLF occurs mainly in the range of 150-600℃,and the latter exhibits asymmetrical peak with a pronounced shoulder.The decomposition process was first analyzed by deconvolution of the experimental DTG curves,followed by reconstruction of the weight loss profiles of two individual processes.Several common isoconversional approaches were applied to calculate the activation energy over a wide range of conversion for the sample,including modified Kissinger-Akahira-Sunose(MKAS),Friedman,and Flynn-Wall-Ozawa.The average activation energy of vegetable-tanned leather fiber was found to be 241.9 kJ mol^(−1) by MKAS method.The activation energy values obtained for the pseudocomponents representing highly-crosslinked and low-crosslinked collagen in VLF were given as 190.6 and 124.8 kJ mol^(−1),respectively.Generalized master plots results suggested that the reaction mechanism for highly-crosslinked collagen follows the random nucleation and growth process at conversion values lower than 0.5.When the conversion is higher than 0.5,the mechanism tends to random scission model.For low-crosslinked collagen,the degradation is mainly governed by random nucleation and nuclei growth.The gaseous products of VLF thermal degradation were analyzed with an online-coupled TG-Fourier transform infrared spectroscopy system.
基金National Natural Science Foundation of China(No.51673177)National Key R&D Program of China(No.2017YFB0308500).
文摘Leather is a collagen-based biomass prepared from raw skins or hides by a series of unit operations, in which the unhairing and fiber opening are extremely important operations. However, the conventional Na2S/Ca(OH)2 system used in unhairing and fiber opening has given rise to the pollution to the environment. It is necessary to develop substitute technology for the Na2S/Ca(OH)2. In the present study, 1-allyl-3-methylimidazolium chloride ([AMIm]Cl) was used to cooperate with dispase for cycle unhairing and one-pot beamhouse to recycle waste bovine hides and com-pared with conventional processing. During those processes, the mechanism of [AMIm]Cl-dispase synergistic unhair-ing and collagen fibers opening were studied. Besides, plant hazard, organic matter and [AMIm]Cl of wastewater from [AMIm]Cl-dispase process were respectively investigated and separated to evaluate the environmental and economic benefits of the [AMIm]Cl-dispase process. As a result, enzyme activity after unhairing by [AMIm]Cl-diapase system for using 5 times is higher than that by KCl-dispase system, and needs lower unhairing time, which is because of rapid penetration of [AMIm]Cl-dispase solution in bovine hides. For this reason, the tensile strength and elastic modulus of tanned leather from [AMIm]Cl-dispase process are higher than those from the KCl-diapase and conventional pro-cesses, and its hydrothermal shrinkage temperature is comparable to that of the conventional one. Because of the 58.13% lower wastewater discharge (WD), 66.60% lower total solids (TS), 97.23% lower ammonia nitrogen (NH3-N), non-toxic wastewater and organic matter recovery in wastewater are reached from [AMIm]Cl-dispase process, which is expected to be an alternative to the conventional process to reduce environmental pollution and realize the sustainable development of technology for leather manufacturing.
