The Experts below are selected from a list of 204 Experts worldwide ranked by ideXlab platform
Wenting You - One of the best experts on this subject based on the ideXlab platform.
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superhydrophobic pvdf ptfe electrospun nanofibrous membranes for desalination by vacuum membrane distillation
Desalination, 2014Co-Authors: Zheqi Dong, Wenting YouAbstract:Abstract In this study, a superhydrophobic nanofibrous membrane was prepared on the basis of an electrospun polyvinylidene fluoride (PVDF)–polytetrafluoroethylene (PTFE) nanofibrous scaffold coupled with a microporous PTFE substrate. The PVDF–PTFE nanofibrous scaffold was fabricated by electrospining of PVDF–PTFE blend solutions, it was observed that by changing the PTFE micro-powder content in the dope solutions from 0 wt.% to 12 wt.%, the water contact angle (WCA) and the liquid entry Pressure (LEPw) of the membrane vary from 130.4° and 84 kPa to 152.2° and 137 kPa, respectively. The superhydrophobic PVDF–PTFE nanofibrous membrane was then tested for desalination by vacuum membrane distillation (VMD), a stable flux of 18.5 kg/m 2 h and salt rejection higher than 99.9% was presented throughout the entire testing period of 15 h, indicating the great potential of the PVDF–PTFE nanofibrous membranes in VMD. For further application of the PVDF–PTFE nanofibrous membranes in VMD, a mathematical model was presented to predict the vapor flux of the novel membrane under various operation conditions. A good agreement between the experimental and theoretical values for vapor fluxes was obtained; the results indicated that the VMD flux increased with the increase of feed temperature and flow rate and decreased with the increase of Permeate Pressure.
Fangbing Li - One of the best experts on this subject based on the ideXlab platform.
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superhydrophobic pvdf ptfe electrospun nanofibrous membranes for desalination by vacuum membrane distillation
Desalination, 2014Co-Authors: Zheqin Dong, Zhenliang Xu, Fangbing LiAbstract:Abstract In this study, a superhydrophobic nanofibrous membrane was prepared on the basis of an electrospun polyvinylidene fluoride (PVDF)–polytetrafluoroethylene (PTFE) nanofibrous scaffold coupled with a microporous PTFE substrate. The PVDF–PTFE nanofibrous scaffold was fabricated by electrospining of PVDF–PTFE blend solutions, it was observed that by changing the PTFE micro-powder content in the dope solutions from 0 wt.% to 12 wt.%, the water contact angle (WCA) and the liquid entry Pressure (LEPw) of the membrane vary from 130.4° and 84 kPa to 152.2° and 137 kPa, respectively. The superhydrophobic PVDF–PTFE nanofibrous membrane was then tested for desalination by vacuum membrane distillation (VMD), a stable flux of 18.5 kg/m2 h and salt rejection higher than 99.9% was presented throughout the entire testing period of 15 h, indicating the great potential of the PVDF–PTFE nanofibrous membranes in VMD. For further application of the PVDF–PTFE nanofibrous membranes in VMD, a mathematical model was presented to predict the vapor flux of the novel membrane under various operation conditions. A good agreement between the experimental and theoretical values for vapor fluxes was obtained; the results indicated that the VMD flux increased with the increase of feed temperature and flow rate and decreased with the increase of Permeate Pressure.
Xianshe Feng - One of the best experts on this subject based on the ideXlab platform.
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vacuum membrane distillation for desalination of water using hollow fiber membranes
Journal of Membrane Science, 2014Co-Authors: Walte Kosa, Yufeng Zhang, Xianshe FengAbstract:Abstract Vacuum membrane distillation (VMD) for desalination of water using hollow fiber membranes with a shell-side feed configuration was investigated. The effects of membrane permeability, water salinity, feed temperature and flow rate on the water permeation rate were evaluated, and the water vapor Pressure buildup in the fiber lumen was analyzed. The Pressure buildup of water vapor in the fiber lumen was shown to adversely affect the driving force for water vapor permeation through the membrane pores, and a mathematical model was developed to describe the mass transfer in VMD by incorporating the Permeate Pressure build up. The model predictions were validated with experimental data. The higher the membrane permeability, the more significant the Permeate Pressure build-up. This is especially important to consider in module design for practical applications. For VMD of saline water, the membrane played a dominant role in the overall mass transfer process, and the significance of the effect of liquid phase resistance on water permeation depended on the membrane permeability. An increase in operating temperature increased the water productivity in VMD, primarily due to increased driving force for permeation, whereas the permeability of the membrane was not significantly affected. A factorial design experiment was carried out to illustrate the effects of main factors involving membrane permeability and operating parameters (feed concentration, temperature and flow rate) on the VMD performance, and some interactions among the effects were shown to occur as well.
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Analysis of Permeate Pressure build-up effects on separation performance of asymmetric hollow fiber membranes
Chemical Engineering Science, 2013Co-Authors: Prodip K. Kundu, Rabitah Zakaria, Amit Chakma, Xianshe FengAbstract:The study rectifies some perceptions about Pressure build-up in hollow fiber membranes. It is a general intuition that operating at higher Pressures Permeates more gases, and sometimes the membrane module is tested or characterized at lower Pressures to reduce gas consumption. It is also perceived that higher Pressure build-up occurs at higher feed Pressures, and membrane performance deteriorates at higher feed Pressures. In this study, the apparent and intrinsic permeances of H2 and N2 in asymmetric cellulose acetate-based hollow fiber membranes were evaluated from gas permeation experiments and numerical analysis. It was shown that though the Permeate Pressure build-up increases as the feed Pressure increases, the effect of the Permeate Pressure build-up on the membrane performance is actually reduced at higher feed Pressures. Membrane performs close to its intrinsic separation properties if it is operated at high feed Pressures, under which conditions the effect of Pressure build-up on the membrane performance is minimized. The Pressure build-up effect was further investigated by evaluating the percentage loss in the driving force due to Permeate Pressure build-up, and it was found that percentage loss in driving force is less at higher feed Pressures than that at lower feed Pressures.
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Permeate Pressure build up in shellside fed hollow fiber pervaporation membranes
Canadian Journal of Chemical Engineering, 1995Co-Authors: Xianshe Feng, Robert Y M HuangAbstract:Pervaporation of water, ethanol and isopropanol through polydimethylsiloxane hollow fiber membranes was studied, with emphasis on elucidating the significance of Permeate Pressure build-up inside the fibers when the shell-feed mode of operation was used. The differential form of the Hagen-Poiseuille equation was used to describe the Permeate Pressure profile, and the theoretical predictions of Permeate productivity were confirmed by experimental data. A parametric analysis showed that the dimensions of the hollow fiber (inside and outside diameters, and length) significantly affected the overall pervaporation performance of a hollow fiber membrane module, and the fiber dimensions must be optimized in order to achieve high productivity. Nous avons etudie la pervaporation de l'eau, de l'ethanol et de l'isopropanol dans des membranes a fibres creuses de polydimethylsiloxane, en nous attachant particulierement a elucider l'importance de la montee en pression du permeat a l'interieur des fibres en fonctionnement “shell feed”. La forme differentielle de l'equation de Hagen-Poiseuille est utilisee pour decrire le profil de pression du permeat, et les predictions theoriques de productivite du permeat sont confirmees par des donnees experimentales. Une analyse parametrique montre que les dimensions de la fibre creuse (diametres interieur et exterieur et longueur) influe de maniere significative sur la performance de pervaporation globale d'un module de membranes a fibres creuses; les dimensions des fibres doivent donc ětre optimisees en vue d'atteindre une productivite elevee.
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dehydration of isopropanol by pervaporation using aromatic polyetherimide membranes
Separation Science and Technology, 1993Co-Authors: Robert Y M Huang, Xianshe FengAbstract:Abstract Aromatic polyetherimide membranes were prepared by the phase inversion method and tested for the pervaporation separation of water from isopropanol with emphasis on the breaking of azeotropic composition and the dehydration of high concentrations of isopropanol. It was found that the membrane selectivity was enhanced by partial evaporation of the solvent in the cast polymer films prior to the gelation step during membrane formation. The membrane performance was shown to be dependent on the feed concentration and the operating temperature. At a feed temperature of 25°C and a Permeate Pressure of 133 Pa, separation factors of 173 and 384 were achieved for the dehydration of isopropanol solutions at 0.68 (azeotropic composition) and 0.96 mole fractions isopropanol, respectively, with reasonably high permeation rates. The utility of the membranes for the proposed separation was demonstrated; however, these membranes were not prepared under optimized conditions and thus a continuous study is required ...
Zheqi Dong - One of the best experts on this subject based on the ideXlab platform.
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superhydrophobic pvdf ptfe electrospun nanofibrous membranes for desalination by vacuum membrane distillation
Desalination, 2014Co-Authors: Zheqi Dong, Wenting YouAbstract:Abstract In this study, a superhydrophobic nanofibrous membrane was prepared on the basis of an electrospun polyvinylidene fluoride (PVDF)–polytetrafluoroethylene (PTFE) nanofibrous scaffold coupled with a microporous PTFE substrate. The PVDF–PTFE nanofibrous scaffold was fabricated by electrospining of PVDF–PTFE blend solutions, it was observed that by changing the PTFE micro-powder content in the dope solutions from 0 wt.% to 12 wt.%, the water contact angle (WCA) and the liquid entry Pressure (LEPw) of the membrane vary from 130.4° and 84 kPa to 152.2° and 137 kPa, respectively. The superhydrophobic PVDF–PTFE nanofibrous membrane was then tested for desalination by vacuum membrane distillation (VMD), a stable flux of 18.5 kg/m 2 h and salt rejection higher than 99.9% was presented throughout the entire testing period of 15 h, indicating the great potential of the PVDF–PTFE nanofibrous membranes in VMD. For further application of the PVDF–PTFE nanofibrous membranes in VMD, a mathematical model was presented to predict the vapor flux of the novel membrane under various operation conditions. A good agreement between the experimental and theoretical values for vapor fluxes was obtained; the results indicated that the VMD flux increased with the increase of feed temperature and flow rate and decreased with the increase of Permeate Pressure.
Zheqin Dong - One of the best experts on this subject based on the ideXlab platform.
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superhydrophobic pvdf ptfe electrospun nanofibrous membranes for desalination by vacuum membrane distillation
Desalination, 2014Co-Authors: Zheqin Dong, Zhenliang Xu, Fangbing LiAbstract:Abstract In this study, a superhydrophobic nanofibrous membrane was prepared on the basis of an electrospun polyvinylidene fluoride (PVDF)–polytetrafluoroethylene (PTFE) nanofibrous scaffold coupled with a microporous PTFE substrate. The PVDF–PTFE nanofibrous scaffold was fabricated by electrospining of PVDF–PTFE blend solutions, it was observed that by changing the PTFE micro-powder content in the dope solutions from 0 wt.% to 12 wt.%, the water contact angle (WCA) and the liquid entry Pressure (LEPw) of the membrane vary from 130.4° and 84 kPa to 152.2° and 137 kPa, respectively. The superhydrophobic PVDF–PTFE nanofibrous membrane was then tested for desalination by vacuum membrane distillation (VMD), a stable flux of 18.5 kg/m2 h and salt rejection higher than 99.9% was presented throughout the entire testing period of 15 h, indicating the great potential of the PVDF–PTFE nanofibrous membranes in VMD. For further application of the PVDF–PTFE nanofibrous membranes in VMD, a mathematical model was presented to predict the vapor flux of the novel membrane under various operation conditions. A good agreement between the experimental and theoretical values for vapor fluxes was obtained; the results indicated that the VMD flux increased with the increase of feed temperature and flow rate and decreased with the increase of Permeate Pressure.