Cellulose acetate butyrate(CAB)is a cellulose ester that is commonly used in applications such as coatings and leather brighteners.However,its appearance in a fibrous form is rarely reported.CAB porous micro/nanofibro...Cellulose acetate butyrate(CAB)is a cellulose ester that is commonly used in applications such as coatings and leather brighteners.However,its appearance in a fibrous form is rarely reported.CAB porous micro/nanofibrous membranes with a large number of nanopores on the fiber surface were successfully prepared by electrospinning with dichloromethane(DCM)/acetone(AC)as the mixed solvent.Apparent morphology,porosity,moisture permeability,air permeability,static water contact angles,and thermal conductivity of the fibrous membranes were investigated at different spinning voltages.The results showed that with the increase of the spinning voltage,the average fiber diameter of the CAB porous micro/nanofibrous membranes gradually decreased and the fiber diameter distribution was more uniform.When the spinning voltage reached 40 kV,the porosity reached 91.38%,the moisture permeability was up to 7430 g/(m^(2)·d),the air permeability was up to 36.289 mm/s,the static water contact angle was up to 145.0°,while the thermal conductivity of the fibrous membranes reached 0.030 W/(m·K).The material can be applied as thermal-insulation,waterproof and moisture-permeable membranes.展开更多
A series of cellulose acetate membranes were prepared by using formamide as additive, and then were hydrolyzed in 4 wt% aqueous NaOH solution for 8 h to obtain regenerated cellulose membranes. The dependence of degree...A series of cellulose acetate membranes were prepared by using formamide as additive, and then were hydrolyzed in 4 wt% aqueous NaOH solution for 8 h to obtain regenerated cellulose membranes. The dependence of degree of substitution, structure, porous properties, solubility and thermal stability on hydrolysis time was studied by chemical titration, Fourier transform infrared spectroscopy, scanning electron microscopy, wide-angle X-ray diffraction, and differential scanning calorimetry, respectively. The results indicated that the pore size of the regenerated cellulose membranes was slightly smaller than that of cellulose acetate membrane, while solvent-resistance, crystallinity and thermostability were significantly improved. This work provides a simple way to prepare the porous cellulose membranes, which not only kept the good pore characteristics of cellulose acetate membranes, but also possessed solvent-resistance, high crystallinity and thermostability. Therefore, the application range of cellulose acetate membranes can be expanded.展开更多
Immobilized cholesterol oxidase (COD) membrane with higher catalytic activity is important for biosensor. In this paper, several procedures for immobilizing COD based on cellulose acetate (CA) membrane are studied. Re...Immobilized cholesterol oxidase (COD) membrane with higher catalytic activity is important for biosensor. In this paper, several procedures for immobilizing COD based on cellulose acetate (CA) membrane are studied. Reasons causing different catalytic activities are also discussed.展开更多
In this work,the viability of Solidago Canadensis L. for cellulose acetate membrane production was tested. The cellulose was extracted from Solidago Canadensis L. stem by organic solvents,and the cellulose diacetate w...In this work,the viability of Solidago Canadensis L. for cellulose acetate membrane production was tested. The cellulose was extracted from Solidago Canadensis L. stem by organic solvents,and the cellulose diacetate was obtained by acetylization of cellulose. The properties of the intermediate products of cellulose pulp and cellulose diacetate were characterized by FT-IR and XRD. Compared with commercial cellulose diacetate,the properties of cellulose diacetate were similar to those of the commercial cellulose diacetate. The cellulose acetate membrane with desirable pure water flux and rejection rate was obtained from cellulose diacetate by solution casting. The membrane showed favorable hydrophilic property so that it had good anti-pollution performance. The maximum pure water flux of the membrane was 27. 21 m L /( cm2· h) and the maximum rejection rate was 80. 39%. The results demonstrated that the membrane obtained from herbaceous plant: Solidago Canadensis L. had good performance of ultrafiltration.展开更多
Although a great progress has been achieved for the development of NF membranes and technologies and SRNF do show a great potential in the separation of organic components, an NF membrane with good separation performa...Although a great progress has been achieved for the development of NF membranes and technologies and SRNF do show a great potential in the separation of organic components, an NF membrane with good separation performance and good resistance to organic solvents are urgently needed for a more complicated situation in practical. In this study, a kind of solvent-resistant nanofiltration (SRNF) membrane was fabricated via interfacial polymerization on a laboratory optimized cellulose acetate (CA) basic membrane. The effects of interfacial polymerization parameters, such as water phase concentration, immersed time in the water phase and in the organic phase, on the pure water flux and rejection rate of C-2R yellow dyestuffs were investigated. A highest dye rejection rate of 72.9% could be obtained by water phase solution containing 1% m-xylylenediamine (mXDA) and organic phase solution with 0.2% trimesoyl chloride (TMC) under immersed time in water phase of 6 minutes and in organic phase of 40 seconds. This membrane demonstrated better resistance to methyl alcohol compared to commercial membrane. This study may offer an avenue to develop a solvent-resistant nanofiltration membrane.展开更多
Polyethylene terephthalate mesh（PET） enhanced cellulose acetate membranes were fabricated via a phase inversion process. The membrane fabrication parameters that may affect the membrane performance were systematical...Polyethylene terephthalate mesh（PET） enhanced cellulose acetate membranes were fabricated via a phase inversion process. The membrane fabrication parameters that may affect the membrane performance were systematically evaluated including the concentration and temperature of the casting polymer solution and the temperature and time of the evaporation, coagulation and annealing processes. The water permeability and reverse salt flux were measured in forward osmosis（FO） mode for determination of the optimal membrane fabrication conditions. The optimal FO membrane shows a typical asymmetric sandwich structure with a mean thickness of about 148.2 μm. The performance of the optimal FO membrane was tested using 0.2 mol/L Na Cl as the feed solution and 1.5 mol/L glucose as the draw solution. The membrane displayed a water flux of 3.47 L/（m2·hr） and salt rejection of95.48% in FO mode. While in pressure retarded osmosis（PRO） mode, the water flux was4.74 L/（m2·hr） and salt rejection 96.03%. The high ratio of water flux in FO mode to that in PRO mode indicates that the fabricated membrane has a lower degree of internal concentration polarization than comparable membranes.展开更多
We fabricate a novel cellulose acetate （CA） ultrafiltration membrane modified by block copolymer F127-b- PDMAEMA, which is synthesized using F127 and DMAEMA via the ARGET ATRP method. Compared to conven- tional ultr...We fabricate a novel cellulose acetate （CA） ultrafiltration membrane modified by block copolymer F127-b- PDMAEMA, which is synthesized using F127 and DMAEMA via the ARGET ATRP method. Compared to conven- tional ultrafiltration membranes, the incorporation of both F 127 and PDMAEMA can not only readily increase the hydrophilicity of the membrane, but also exhibit stimuli-responsiveness to temperature and pH. Fourier transform infrared spectroscopy （FT-IR）, nuclear magnetic resonance spectroscopy （NMR）, and gel permeation chromatog- raphy （GPC） are employed to analyze the structure of the F 127-b-PDMAEMA. The membrane properties are eval- uated via scanning electron microscope （SEM） imaging, porosity test, automatic target recognition Fourier trans- form infrared spectroscopy （ATR-FTIR）, water contact angle test and permeation test. The results indicate that the F 127-b-PDMAEMA is an excellent pore agent, which contributes to an enhancement of the membrane in sensitivity to temperature and pH. The modified membrane also exhibits lower water contact angle （64.5~）, which is attributed to the good anti-fouling performance and high water permeation.展开更多
Herein, the fabrication of cellulose acetate (CA) silica-based nanocomposite membranes via the dry-wetphase inversion procedure for water desalination was investigated. The modified and unmodified silicananoparticles ...Herein, the fabrication of cellulose acetate (CA) silica-based nanocomposite membranes via the dry-wetphase inversion procedure for water desalination was investigated. The modified and unmodified silicananoparticles (MSNPs and SNPs) were prepared by the sol-gel technique. The effect of the SNPs andMSNPs was investigated on the CA membrane's properties and their performance for water desalination.The CA nanocomposite membranes were characterized to study their structure, hydrophilicity, andmorphology. The fabricated nanocomposite membranes showed hydrophilic surface properties. Theperformance of reverse osmosis (RO) membranes was measured using a crossflow RO unit at 10 bar(1 bar = 0.1 MPa). The membrane with 10 mg of SNPs enhanced permeate water flux compared to thepristine CA membrane by 1.6 L/(m2·h). The effect of MSNPs on the nanocomposites' performance waslower than their counterpart in the case of adding SNPs. The membrane with 30 mg of MSNPs showedthe highest permeate water flux among other nanocomposite membranes with a value oAQSf 35.7 L/(m2·h)at 24 bar.展开更多
Freshwater scarcity is a critical challenge that human society has to face in the 21st century.Desalination of seawater by reverse osmosis(RO)membranes was regarded as the most promising technology to overcome the cha...Freshwater scarcity is a critical challenge that human society has to face in the 21st century.Desalination of seawater by reverse osmosis(RO)membranes was regarded as the most promising technology to overcome the challenge given that plenty of potential fresh water resources in oceans.However,the requirements for high desalination efficiency in terms of permeation flux and rejection rate become the bottle-neck which needs to be broken down by developing novel RO membranes with new structure and composition.Cellulose acetate RO membranes exhibited long durability,chlorine resistance,and outstanding desalination efficiency that are worthy of being recalled to address the current shortcomings brought by polyamide RO membranes.In terms of performance enhancement,it is also important to use new ideas and to develop new strategies to modify cellulose acetate RO membranes in response to those complex challenges.Therefore,we focused on the state of the art cellulose acetate RO membranes and discussed the strategies on membrane structural manipulation adjusted by either phase separation or additives,which offered anti-fouling,anti-bacterial,anti-chlorine,durability,and thermo-mechanical properties to the modified membranes associated with the desalination performance,i.e.,permeation flux and rejection rate.The relationship between membrane structure and desalination efficiency was investigated and established to guide the development of cellulose acetate RO membranes for desalination.展开更多
基金National Natural Science Foundation of China(No.52203056)。
文摘Cellulose acetate butyrate(CAB)is a cellulose ester that is commonly used in applications such as coatings and leather brighteners.However,its appearance in a fibrous form is rarely reported.CAB porous micro/nanofibrous membranes with a large number of nanopores on the fiber surface were successfully prepared by electrospinning with dichloromethane(DCM)/acetone(AC)as the mixed solvent.Apparent morphology,porosity,moisture permeability,air permeability,static water contact angles,and thermal conductivity of the fibrous membranes were investigated at different spinning voltages.The results showed that with the increase of the spinning voltage,the average fiber diameter of the CAB porous micro/nanofibrous membranes gradually decreased and the fiber diameter distribution was more uniform.When the spinning voltage reached 40 kV,the porosity reached 91.38%,the moisture permeability was up to 7430 g/(m^(2)·d),the air permeability was up to 36.289 mm/s,the static water contact angle was up to 145.0°,while the thermal conductivity of the fibrous membranes reached 0.030 W/(m·K).The material can be applied as thermal-insulation,waterproof and moisture-permeable membranes.
基金This work was supported by the National Natural Science Foundation of China (No. 59933070) and Laboratory of Cellulose and Lignocellulosic Chemistry, Guangzhou Institute of Chemistry, Chinese Academy of Sciences.
文摘A series of cellulose acetate membranes were prepared by using formamide as additive, and then were hydrolyzed in 4 wt% aqueous NaOH solution for 8 h to obtain regenerated cellulose membranes. The dependence of degree of substitution, structure, porous properties, solubility and thermal stability on hydrolysis time was studied by chemical titration, Fourier transform infrared spectroscopy, scanning electron microscopy, wide-angle X-ray diffraction, and differential scanning calorimetry, respectively. The results indicated that the pore size of the regenerated cellulose membranes was slightly smaller than that of cellulose acetate membrane, while solvent-resistance, crystallinity and thermostability were significantly improved. This work provides a simple way to prepare the porous cellulose membranes, which not only kept the good pore characteristics of cellulose acetate membranes, but also possessed solvent-resistance, high crystallinity and thermostability. Therefore, the application range of cellulose acetate membranes can be expanded.
基金Funded by the Fund of the Doctoral Program of Higher Ed-ucation( No.98049703)
文摘Immobilized cholesterol oxidase (COD) membrane with higher catalytic activity is important for biosensor. In this paper, several procedures for immobilizing COD based on cellulose acetate (CA) membrane are studied. Reasons causing different catalytic activities are also discussed.
文摘In this work,the viability of Solidago Canadensis L. for cellulose acetate membrane production was tested. The cellulose was extracted from Solidago Canadensis L. stem by organic solvents,and the cellulose diacetate was obtained by acetylization of cellulose. The properties of the intermediate products of cellulose pulp and cellulose diacetate were characterized by FT-IR and XRD. Compared with commercial cellulose diacetate,the properties of cellulose diacetate were similar to those of the commercial cellulose diacetate. The cellulose acetate membrane with desirable pure water flux and rejection rate was obtained from cellulose diacetate by solution casting. The membrane showed favorable hydrophilic property so that it had good anti-pollution performance. The maximum pure water flux of the membrane was 27. 21 m L /( cm2· h) and the maximum rejection rate was 80. 39%. The results demonstrated that the membrane obtained from herbaceous plant: Solidago Canadensis L. had good performance of ultrafiltration.
文摘Although a great progress has been achieved for the development of NF membranes and technologies and SRNF do show a great potential in the separation of organic components, an NF membrane with good separation performance and good resistance to organic solvents are urgently needed for a more complicated situation in practical. In this study, a kind of solvent-resistant nanofiltration (SRNF) membrane was fabricated via interfacial polymerization on a laboratory optimized cellulose acetate (CA) basic membrane. The effects of interfacial polymerization parameters, such as water phase concentration, immersed time in the water phase and in the organic phase, on the pure water flux and rejection rate of C-2R yellow dyestuffs were investigated. A highest dye rejection rate of 72.9% could be obtained by water phase solution containing 1% m-xylylenediamine (mXDA) and organic phase solution with 0.2% trimesoyl chloride (TMC) under immersed time in water phase of 6 minutes and in organic phase of 40 seconds. This membrane demonstrated better resistance to methyl alcohol compared to commercial membrane. This study may offer an avenue to develop a solvent-resistant nanofiltration membrane.
基金the financial support of the National Natural Science Foundation of China(Nos.51378491,21307149)
文摘Polyethylene terephthalate mesh（PET） enhanced cellulose acetate membranes were fabricated via a phase inversion process. The membrane fabrication parameters that may affect the membrane performance were systematically evaluated including the concentration and temperature of the casting polymer solution and the temperature and time of the evaporation, coagulation and annealing processes. The water permeability and reverse salt flux were measured in forward osmosis（FO） mode for determination of the optimal membrane fabrication conditions. The optimal FO membrane shows a typical asymmetric sandwich structure with a mean thickness of about 148.2 μm. The performance of the optimal FO membrane was tested using 0.2 mol/L Na Cl as the feed solution and 1.5 mol/L glucose as the draw solution. The membrane displayed a water flux of 3.47 L/（m2·hr） and salt rejection of95.48% in FO mode. While in pressure retarded osmosis（PRO） mode, the water flux was4.74 L/（m2·hr） and salt rejection 96.03%. The high ratio of water flux in FO mode to that in PRO mode indicates that the fabricated membrane has a lower degree of internal concentration polarization than comparable membranes.
基金This work was financially supported by the Funda- mental Research Funds for the Central Universities of China （Nos. 3207045403, 3207045409）, National Natu- ral Science Foundation of China （Nos. 21576050, 51602052）, Jiangsu Provincial Natural Science Founda- tion of China （No. BK20150604） and a Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions （PAPD）.
文摘We fabricate a novel cellulose acetate （CA） ultrafiltration membrane modified by block copolymer F127-b- PDMAEMA, which is synthesized using F127 and DMAEMA via the ARGET ATRP method. Compared to conven- tional ultrafiltration membranes, the incorporation of both F 127 and PDMAEMA can not only readily increase the hydrophilicity of the membrane, but also exhibit stimuli-responsiveness to temperature and pH. Fourier transform infrared spectroscopy （FT-IR）, nuclear magnetic resonance spectroscopy （NMR）, and gel permeation chromatog- raphy （GPC） are employed to analyze the structure of the F 127-b-PDMAEMA. The membrane properties are eval- uated via scanning electron microscope （SEM） imaging, porosity test, automatic target recognition Fourier trans- form infrared spectroscopy （ATR-FTIR）, water contact angle test and permeation test. The results indicate that the F 127-b-PDMAEMA is an excellent pore agent, which contributes to an enhancement of the membrane in sensitivity to temperature and pH. The modified membrane also exhibits lower water contact angle （64.5~）, which is attributed to the good anti-fouling performance and high water permeation.
文摘Herein, the fabrication of cellulose acetate (CA) silica-based nanocomposite membranes via the dry-wetphase inversion procedure for water desalination was investigated. The modified and unmodified silicananoparticles (MSNPs and SNPs) were prepared by the sol-gel technique. The effect of the SNPs andMSNPs was investigated on the CA membrane's properties and their performance for water desalination.The CA nanocomposite membranes were characterized to study their structure, hydrophilicity, andmorphology. The fabricated nanocomposite membranes showed hydrophilic surface properties. Theperformance of reverse osmosis (RO) membranes was measured using a crossflow RO unit at 10 bar(1 bar = 0.1 MPa). The membrane with 10 mg of SNPs enhanced permeate water flux compared to thepristine CA membrane by 1.6 L/(m2·h). The effect of MSNPs on the nanocomposites' performance waslower than their counterpart in the case of adding SNPs. The membrane with 30 mg of MSNPs showedthe highest permeate water flux among other nanocomposite membranes with a value oAQSf 35.7 L/(m2·h)at 24 bar.
基金the National Natural Science Foundation of China(51673011).
文摘Freshwater scarcity is a critical challenge that human society has to face in the 21st century.Desalination of seawater by reverse osmosis(RO)membranes was regarded as the most promising technology to overcome the challenge given that plenty of potential fresh water resources in oceans.However,the requirements for high desalination efficiency in terms of permeation flux and rejection rate become the bottle-neck which needs to be broken down by developing novel RO membranes with new structure and composition.Cellulose acetate RO membranes exhibited long durability,chlorine resistance,and outstanding desalination efficiency that are worthy of being recalled to address the current shortcomings brought by polyamide RO membranes.In terms of performance enhancement,it is also important to use new ideas and to develop new strategies to modify cellulose acetate RO membranes in response to those complex challenges.Therefore,we focused on the state of the art cellulose acetate RO membranes and discussed the strategies on membrane structural manipulation adjusted by either phase separation or additives,which offered anti-fouling,anti-bacterial,anti-chlorine,durability,and thermo-mechanical properties to the modified membranes associated with the desalination performance,i.e.,permeation flux and rejection rate.The relationship between membrane structure and desalination efficiency was investigated and established to guide the development of cellulose acetate RO membranes for desalination.
