Membrane contactor is regarded as a promising method for reaction and process intensification. The feasibility of formaldehyde carbonylation to synthesize glycolic acid using polytetrafluoroethylene(PTFE)membrane cont...Membrane contactor is regarded as a promising method for reaction and process intensification. The feasibility of formaldehyde carbonylation to synthesize glycolic acid using polytetrafluoroethylene(PTFE)membrane contactor has been proved in our previous study. In this paper, the effect of membrane microstructure on process performance was further investigated. Three porous PTFE hollow fibers with different pore sizes and one polydimethylsiloxane(PDMS)/PTFE composite membrane with dense layer were fabricated for comparison. The physical and chemical properties of four membranes, including chemical composition, morphology, contact angle, liquid entry pressure, thermodynamic analysis and gas permeability, were systemically characterized. Experiments of formaldehyde carbonylation under different reaction conditions were conducted. The results indicated that the yield of glycolic acid increased with decreasing pore size for porous membranes, which was due to the improvement of wetting behavior. The dense layer of PDMS in composite hollow fiber could effectively prevent the solvent from entering membrane pores, thus the membrane exhibited the best performance. At reaction temperature of 120℃ and operation pressure of 3.0 MPa, the yield of glycolic acid was always higher than 90% as the mass ratio of trioxane and phosphotungstic acid increased from 0.2:1 to 0.8:1. The highest turnover frequency was up to 26.37 mol·g^(-1)·h^(-1). This study provided a reference for the understanding and optimization of membrane contactors for the synthesis of glycolic acid using solvent with low surface tension.展开更多
In order to obtain mechanically stable membrane for practical application, the imprinted polymer was synthesized in the pores of polyfluoromembrane, the binding and transport ability of the membrane were studied.
Low-temperature selective catalytic reduction of NOx combined with dust removal technique due to its energy conservation characteristic has been attracted much attention for fume purification.In this work,the MnOx wra...Low-temperature selective catalytic reduction of NOx combined with dust removal technique due to its energy conservation characteristic has been attracted much attention for fume purification.In this work,the MnOx wrapped PTFE membrane with efficient dust removal and low-temperature NH3-SCR has been prepared with a facile route.MnOxwith different crystal structures was uniformly grown around the PTFE fibrils through water bath.The flower-sphere-like MnOx@PTFE(O-MnOx@PTFE)and lamellar-interlaced ripple-like MnOx@PTFE(W-MnOx@PTFE)have large specific surface area which is favorable for enhancing catalytic performance.Also,the uniformly wrapped W-MnOxaround the PTFE fibrils optimized the pore structure for ultrafine dust capture.The membrane can almost 100%reject particles that are smaller than 1.0μm with a low filtration resistance.Meanwhile,W-MnOx@PTFE with more surface chemisorbed oxygen has the best NO conversion efficiency of 100%at a comparatively low and wide activity temperature window of 160–210°C,which is far to the thermal limitation of the PTFE.Therefore,this efficient and energy conserving membrane has a bright application prospects for tail gas treatment compared to the original treatment process.展开更多
concentrating sulfuric acid by membrane distillation in a flat sheet direct contact membrane distillation device with a self made metal PTFE composite membrane has been studied. The effect of sulfuric acid concentrati...concentrating sulfuric acid by membrane distillation in a flat sheet direct contact membrane distillation device with a self made metal PTFE composite membrane has been studied. The effect of sulfuric acid concentration of feed, the flowrate and liquor temperature in high temperature side and low temperature side on the flux and separation efficiency is investigated. The stability of this composite membrane is also inspected. The experimental results show that the metal PTFE composite membrane can be used in membrane distillation, and its properties are very stable. It is feasible to concentrate sulfuric acid by membrane distillation with this membrane.展开更多
By means of texturing with organic conductive fiber, and then being treated with JAM-Y1 anti-bacteria agent, in the end, treated with the XL-550 waterproof agent, the PET fabric has permanent antistatic, anti-bacteria...By means of texturing with organic conductive fiber, and then being treated with JAM-Y1 anti-bacteria agent, in the end, treated with the XL-550 waterproof agent, the PET fabric has permanent antistatic, anti-bacteria and waterproof and anti-oil properties. The PET fabric was laminated with PTFE membrane by paste dot coating, and then coated by Poly(ether-ester) solution in a direct process. The filter efficiency of NaCl aerosol, penetration property of poliomyelitis virus in liquid and animalcule in air of PET fabric laminated with PTFE membrane are measured. The properties show that the PET fabric laminated with PTFE membrane can separate SARS virus in air and liquid. The protective mechanism is also discussed in the article.展开更多
A hybrid system combined with a non-contact membrane and bubbling absorption is proposed to capture CO_(2) from flue gas.The non-contact way of membrane and liquid absorbent effectively avoids the reduction of gas dif...A hybrid system combined with a non-contact membrane and bubbling absorption is proposed to capture CO_(2) from flue gas.The non-contact way of membrane and liquid absorbent effectively avoids the reduction of gas diffusion flux through the membrane.High-porosity ceramic membranes in hybrid systems are used for gas-solid separation in fuel gas treatment.Due to the high content of H_(2)O and cement dust in the flue gas of the cement plant,the membrane is hydrophobically modified by polytetrafluoroethylene(PTFE)to improve its anti-water,anti-fouling,and self-cleaning performances.The results show that the diffusion flux of CO_(2) through the membrane is still higher than 7.0×10^(−3) mol/m^(2)s(20%CO_(2) concentration)even under the influence of water and cement dust.In addition,slaked lime selected as the absorbent is cheap and the product after bubbling absorption is nano-scale light calcium carbonate.To sum up,the hybrid system combining non-contact membrane and bubbling absorption is expected to be used to capture carbon dioxide from the flue gas of the cement plant.展开更多
In the present study,the effects of relative humidity on filtrating coal-fired fly ash with hydrophobic poly tetra fluoroethylene(PTFE) membranes were investigated.The intergranular force of particulate matter at diff...In the present study,the effects of relative humidity on filtrating coal-fired fly ash with hydrophobic poly tetra fluoroethylene(PTFE) membranes were investigated.The intergranular force of particulate matter at different RH conditions was measured by analyzing the critical angle between particles.Effects of humidity(from 30% to 70%) on filtration pressure drop and membrane fouling conditions were characterized.It was found the membrane showed optimal filtration resistance of 530 Pa at RH of 60% and the gas permeance can be maintained at 1440 m^(3)·m^(-2)·h^(-1)·kPa^(-1).Moreover,to optimize the operation parameters for this filtration system,effects of fly ash concentration,diameter,membrane pore size,and gas velocities were systematically investigated.展开更多
Radiation-induced grafting of styrene onto polytetrafluoroethylene (PTFE) membranes was studied by a simultaneous irradiation technique.Grafting was carded out usingγ-radiation from a ^(60)Co source at room temperatu...Radiation-induced grafting of styrene onto polytetrafluoroethylene (PTFE) membranes was studied by a simultaneous irradiation technique.Grafting was carded out usingγ-radiation from a ^(60)Co source at room temperature. Effects of absorbed dose,atmosphere,dose rate,and the concentration of initial monomer on the degree of grafting (DOG) were investigated and the most appropriate grafting condition was obtained.Subsequently,sulphonation of the grafted PTFE membrane (PTFE-g-PS) was carried out and a series of ion exchange membranes (PTFE-g-PSSA) was prepared.Further characterizations of FTIR,TGA,and SEM testified that grafting and sulphonation of the membranes were successfully processed;moreover,grafting of styrene not only occurred in the surface of PTFE membrane,but also in the micropores of the membrane.Ion exchange capacity (IEC) and conductivity were found increase with the grafting yield.The results suggest that at a low dose,such as 17 kGy,the ion exchange membrane (IEM) which will be suitable for vanadium redox battery (VRB) use can be obtained.展开更多
液滴撞击固体表面是自然界的常见现象,研究超疏水表面的液滴撞击对其润湿性的影响,对于超疏水性材料的潜在应用具有重要的科学意义。采用3、10、20 min氧等离子体处理(OPT)和1 min八氟环丁烷等离子体聚合沉积(PPD)的等离子体方法改性聚...液滴撞击固体表面是自然界的常见现象,研究超疏水表面的液滴撞击对其润湿性的影响,对于超疏水性材料的潜在应用具有重要的科学意义。采用3、10、20 min氧等离子体处理(OPT)和1 min八氟环丁烷等离子体聚合沉积(PPD)的等离子体方法改性聚四氟乙烯(PTFE)表面,获得具有不同尺寸和间距的微/纳米锥的超疏水PTFE表面,研究射频等离子体改性PTFE表面的液滴静态接触角、滚动角及液滴撞击动力学行为,分析在不同个数液滴撞击后PTFE表面的润湿性和液滴撞击行为变化,确定PTFE表面液滴撞击起电效应的影响机制。结果表明:通过1~9个液滴撞击后,PTFE表面的静态接触角随撞击液滴数量增加而减小,导致静态接触角低于150°;液滴滚动角随撞击液滴数量增加而增大,造成液滴滚动角高于10°。撞击液滴的接触时间随撞击液滴数量增加而增大,回弹系数随撞击液滴数量增加而减小。随撞击液滴数量增加,回弹液滴的正电荷和PTFE表面的负电压增大,PTFE表面的负电荷对液滴产生强吸引作用,导致低粘附超疏水性被破坏。3 min OPT和1 min PPD改性PTFE表面的纳米锥间距小,密度大,表面负电荷量增加明显,造成PTFE表面的疏水性降低的程度最显著。研究结果可为改善超疏水稳定性的表面织构设计提供理论依据。展开更多
In the era of advanced wearable electronic devices,the triboelectric nanogenerators(TENGs)as energy harvesting and self-powered sensing units hold great promise.Selecting appropriate triboelectric material is the cruc...In the era of advanced wearable electronic devices,the triboelectric nanogenerators(TENGs)as energy harvesting and self-powered sensing units hold great promise.Selecting appropriate triboelectric material is the crucial factor to optimize the performance of TENG,while polytetrafluoroethylene(PTFE)stands out as a highly versatile option among the various materials.In this study,we present an ultrafine nanofibrous PTFE(NF-PTFE)films prepared by novel in-situ fibrillation strategy as the triboelectric material in TENG devices.The innovative processing methodology facilely addresses the dilemma between high porosity and fine pore size of traditional porous PTFE films,meanwhile achieves exceptional mechanical strength,hydrophobicity,air permeability,and chemical resistance of the films.With the integration of nanofibrous PTFE films into contact-separation mode TENG and droplet-based TENG,these devices realize the peak electrical output of 131 V/10.8μA and 54 V/14μA with great durability,which surpass the performance of TENGs using traditional expanded PTFE films.Furthermore,a smart glove capable of recognizing hand gestures is proposed,which demonstrates the versatility,flexibility,and practicality of this material for potential use in smart devices.This reported NF-PTFE film provides insights for the design of high-performance TENG device for advanced wearable electrical applications.展开更多
Surface modification on a polytetrafluoroethylene （PTFE） panel was performed with sequential nitrogen plasma treatments and surface-initiated polymerization. By introducing COO- groups to the surface of the PTFE pan...Surface modification on a polytetrafluoroethylene （PTFE） panel was performed with sequential nitrogen plasma treatments and surface-initiated polymerization. By introducing COO- groups to the surface of the PTFE panel through grafting polymerization of acrylic acid （AA）, a transparent poly （acrylic acid） （PAA） membrane was achieved from acrylic acid solution. Grafting polymerization initiating from the active group5 was achieved on the PTFE panel surface after the nitrogen plasma treatment. Utilizing the acrylic acid as monomers, with COO- groups as cross link sites to form reticulation structure, a transparent poly （acrylic acid） membrane with arborescent macromolecular structure was formed on the PTFE panel surface. Analysis meth- ods, such as fourier transform infrared spectroscopy （FTIR）, microscopy and X-ray photoelectron spectroscopy （XPS）, were utilized to characterize the structures of the macromolecule membrane on the PTFE panel surface. A contact angle measurement was performed to characterize the modified PTFE panels. The surface hydrophilicities of modified PTFE panels were significantly enhanced after the plasma treatment. It was shown that the grafting rate is related to the treating time and the power of plasma.展开更多
基金the financial support from Dalian Institute of Chemical Physics (DMTO201604)Focus Area Innovation Team Support Plan of Dalian (2021RT03)+1 种基金National Natural Science Foundation of China (21878284)Regional Development Young Scholars of the Chinese Academy of Sciences。
文摘Membrane contactor is regarded as a promising method for reaction and process intensification. The feasibility of formaldehyde carbonylation to synthesize glycolic acid using polytetrafluoroethylene(PTFE)membrane contactor has been proved in our previous study. In this paper, the effect of membrane microstructure on process performance was further investigated. Three porous PTFE hollow fibers with different pore sizes and one polydimethylsiloxane(PDMS)/PTFE composite membrane with dense layer were fabricated for comparison. The physical and chemical properties of four membranes, including chemical composition, morphology, contact angle, liquid entry pressure, thermodynamic analysis and gas permeability, were systemically characterized. Experiments of formaldehyde carbonylation under different reaction conditions were conducted. The results indicated that the yield of glycolic acid increased with decreasing pore size for porous membranes, which was due to the improvement of wetting behavior. The dense layer of PDMS in composite hollow fiber could effectively prevent the solvent from entering membrane pores, thus the membrane exhibited the best performance. At reaction temperature of 120℃ and operation pressure of 3.0 MPa, the yield of glycolic acid was always higher than 90% as the mass ratio of trioxane and phosphotungstic acid increased from 0.2:1 to 0.8:1. The highest turnover frequency was up to 26.37 mol·g^(-1)·h^(-1). This study provided a reference for the understanding and optimization of membrane contactors for the synthesis of glycolic acid using solvent with low surface tension.
基金The authors thank the National Natural Science Foundation of China(No.29975014)Tianjin Natural Science Foundation(No.003602211)the Doctoral Foundation of Educational Ministry,China(No.20020055002)for financial support.
文摘In order to obtain mechanically stable membrane for practical application, the imprinted polymer was synthesized in the pores of polyfluoromembrane, the binding and transport ability of the membrane were studied.
文摘Low-temperature selective catalytic reduction of NOx combined with dust removal technique due to its energy conservation characteristic has been attracted much attention for fume purification.In this work,the MnOx wrapped PTFE membrane with efficient dust removal and low-temperature NH3-SCR has been prepared with a facile route.MnOxwith different crystal structures was uniformly grown around the PTFE fibrils through water bath.The flower-sphere-like MnOx@PTFE(O-MnOx@PTFE)and lamellar-interlaced ripple-like MnOx@PTFE(W-MnOx@PTFE)have large specific surface area which is favorable for enhancing catalytic performance.Also,the uniformly wrapped W-MnOxaround the PTFE fibrils optimized the pore structure for ultrafine dust capture.The membrane can almost 100%reject particles that are smaller than 1.0μm with a low filtration resistance.Meanwhile,W-MnOx@PTFE with more surface chemisorbed oxygen has the best NO conversion efficiency of 100%at a comparatively low and wide activity temperature window of 160–210°C,which is far to the thermal limitation of the PTFE.Therefore,this efficient and energy conserving membrane has a bright application prospects for tail gas treatment compared to the original treatment process.
文摘concentrating sulfuric acid by membrane distillation in a flat sheet direct contact membrane distillation device with a self made metal PTFE composite membrane has been studied. The effect of sulfuric acid concentration of feed, the flowrate and liquor temperature in high temperature side and low temperature side on the flux and separation efficiency is investigated. The stability of this composite membrane is also inspected. The experimental results show that the metal PTFE composite membrane can be used in membrane distillation, and its properties are very stable. It is feasible to concentrate sulfuric acid by membrane distillation with this membrane.
文摘By means of texturing with organic conductive fiber, and then being treated with JAM-Y1 anti-bacteria agent, in the end, treated with the XL-550 waterproof agent, the PET fabric has permanent antistatic, anti-bacteria and waterproof and anti-oil properties. The PET fabric was laminated with PTFE membrane by paste dot coating, and then coated by Poly(ether-ester) solution in a direct process. The filter efficiency of NaCl aerosol, penetration property of poliomyelitis virus in liquid and animalcule in air of PET fabric laminated with PTFE membrane are measured. The properties show that the PET fabric laminated with PTFE membrane can separate SARS virus in air and liquid. The protective mechanism is also discussed in the article.
文摘A hybrid system combined with a non-contact membrane and bubbling absorption is proposed to capture CO_(2) from flue gas.The non-contact way of membrane and liquid absorbent effectively avoids the reduction of gas diffusion flux through the membrane.High-porosity ceramic membranes in hybrid systems are used for gas-solid separation in fuel gas treatment.Due to the high content of H_(2)O and cement dust in the flue gas of the cement plant,the membrane is hydrophobically modified by polytetrafluoroethylene(PTFE)to improve its anti-water,anti-fouling,and self-cleaning performances.The results show that the diffusion flux of CO_(2) through the membrane is still higher than 7.0×10^(−3) mol/m^(2)s(20%CO_(2) concentration)even under the influence of water and cement dust.In addition,slaked lime selected as the absorbent is cheap and the product after bubbling absorption is nano-scale light calcium carbonate.To sum up,the hybrid system combining non-contact membrane and bubbling absorption is expected to be used to capture carbon dioxide from the flue gas of the cement plant.
基金supported by the National Key Research and Development Project of China (2018YFE0203500)the High-end Research and Training Project for Specialty Leading Person of Jiangsu Higher Vocational Colleges (2020GRGDYX039)the Qing Lan Project of Jiangsu Colleges。
文摘In the present study,the effects of relative humidity on filtrating coal-fired fly ash with hydrophobic poly tetra fluoroethylene(PTFE) membranes were investigated.The intergranular force of particulate matter at different RH conditions was measured by analyzing the critical angle between particles.Effects of humidity(from 30% to 70%) on filtration pressure drop and membrane fouling conditions were characterized.It was found the membrane showed optimal filtration resistance of 530 Pa at RH of 60% and the gas permeance can be maintained at 1440 m^(3)·m^(-2)·h^(-1)·kPa^(-1).Moreover,to optimize the operation parameters for this filtration system,effects of fly ash concentration,diameter,membrane pore size,and gas velocities were systematically investigated.
基金Supported by The Scientific Research Foundation of State's Education Ministry for the Returned Overseas Chinese Scholars.
文摘Radiation-induced grafting of styrene onto polytetrafluoroethylene (PTFE) membranes was studied by a simultaneous irradiation technique.Grafting was carded out usingγ-radiation from a ^(60)Co source at room temperature. Effects of absorbed dose,atmosphere,dose rate,and the concentration of initial monomer on the degree of grafting (DOG) were investigated and the most appropriate grafting condition was obtained.Subsequently,sulphonation of the grafted PTFE membrane (PTFE-g-PS) was carried out and a series of ion exchange membranes (PTFE-g-PSSA) was prepared.Further characterizations of FTIR,TGA,and SEM testified that grafting and sulphonation of the membranes were successfully processed;moreover,grafting of styrene not only occurred in the surface of PTFE membrane,but also in the micropores of the membrane.Ion exchange capacity (IEC) and conductivity were found increase with the grafting yield.The results suggest that at a low dose,such as 17 kGy,the ion exchange membrane (IEM) which will be suitable for vanadium redox battery (VRB) use can be obtained.
文摘液滴撞击固体表面是自然界的常见现象,研究超疏水表面的液滴撞击对其润湿性的影响,对于超疏水性材料的潜在应用具有重要的科学意义。采用3、10、20 min氧等离子体处理(OPT)和1 min八氟环丁烷等离子体聚合沉积(PPD)的等离子体方法改性聚四氟乙烯(PTFE)表面,获得具有不同尺寸和间距的微/纳米锥的超疏水PTFE表面,研究射频等离子体改性PTFE表面的液滴静态接触角、滚动角及液滴撞击动力学行为,分析在不同个数液滴撞击后PTFE表面的润湿性和液滴撞击行为变化,确定PTFE表面液滴撞击起电效应的影响机制。结果表明:通过1~9个液滴撞击后,PTFE表面的静态接触角随撞击液滴数量增加而减小,导致静态接触角低于150°;液滴滚动角随撞击液滴数量增加而增大,造成液滴滚动角高于10°。撞击液滴的接触时间随撞击液滴数量增加而增大,回弹系数随撞击液滴数量增加而减小。随撞击液滴数量增加,回弹液滴的正电荷和PTFE表面的负电压增大,PTFE表面的负电荷对液滴产生强吸引作用,导致低粘附超疏水性被破坏。3 min OPT和1 min PPD改性PTFE表面的纳米锥间距小,密度大,表面负电荷量增加明显,造成PTFE表面的疏水性降低的程度最显著。研究结果可为改善超疏水稳定性的表面织构设计提供理论依据。
基金support from the National Natural Science Foundation of China(No.52175341)Shandong Provincial Natural Science Foundation(No.ZR2022JQ24).
文摘In the era of advanced wearable electronic devices,the triboelectric nanogenerators(TENGs)as energy harvesting and self-powered sensing units hold great promise.Selecting appropriate triboelectric material is the crucial factor to optimize the performance of TENG,while polytetrafluoroethylene(PTFE)stands out as a highly versatile option among the various materials.In this study,we present an ultrafine nanofibrous PTFE(NF-PTFE)films prepared by novel in-situ fibrillation strategy as the triboelectric material in TENG devices.The innovative processing methodology facilely addresses the dilemma between high porosity and fine pore size of traditional porous PTFE films,meanwhile achieves exceptional mechanical strength,hydrophobicity,air permeability,and chemical resistance of the films.With the integration of nanofibrous PTFE films into contact-separation mode TENG and droplet-based TENG,these devices realize the peak electrical output of 131 V/10.8μA and 54 V/14μA with great durability,which surpass the performance of TENGs using traditional expanded PTFE films.Furthermore,a smart glove capable of recognizing hand gestures is proposed,which demonstrates the versatility,flexibility,and practicality of this material for potential use in smart devices.This reported NF-PTFE film provides insights for the design of high-performance TENG device for advanced wearable electrical applications.
基金supported by National Natural Science Foundation of China (No. 10975162)Knowledge Innovation Project of Young Talent, Hefei Institutes of Physical Science, CAS (Nos. 075FCQ0126, Y05FCQ0127)
文摘Surface modification on a polytetrafluoroethylene （PTFE） panel was performed with sequential nitrogen plasma treatments and surface-initiated polymerization. By introducing COO- groups to the surface of the PTFE panel through grafting polymerization of acrylic acid （AA）, a transparent poly （acrylic acid） （PAA） membrane was achieved from acrylic acid solution. Grafting polymerization initiating from the active group5 was achieved on the PTFE panel surface after the nitrogen plasma treatment. Utilizing the acrylic acid as monomers, with COO- groups as cross link sites to form reticulation structure, a transparent poly （acrylic acid） membrane with arborescent macromolecular structure was formed on the PTFE panel surface. Analysis meth- ods, such as fourier transform infrared spectroscopy （FTIR）, microscopy and X-ray photoelectron spectroscopy （XPS）, were utilized to characterize the structures of the macromolecule membrane on the PTFE panel surface. A contact angle measurement was performed to characterize the modified PTFE panels. The surface hydrophilicities of modified PTFE panels were significantly enhanced after the plasma treatment. It was shown that the grafting rate is related to the treating time and the power of plasma.
