Documents disponibles écrits par cet auteur

Double - skinned forward osmosis membranes for reducing internal concentration polarization within the porous sublayer / Kai Yu Wang in Industrial & engineering chemistry research, Vol. 49 N° 10 (Mai 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 10 (Mai 2010) . - pp. 4824–4831 Titre : Double - skinned forward osmosis membranes for reducing internal concentration polarization within the porous sublayer Type de document : texte imprimé Auteurs : Kai Yu Wang, Auteur ; Rui Chin Ong, Auteur ; Tai-Shung Chung, Auteur Année de publication : 2010 Article en page(s) : pp. 4824–4831 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Osmosis  Membranes Résumé : A scheme to fabricate forward osmosis membranes comprising a highly porous sublayer sandwiched between two selective skin layers via phase inversion was proposed. One severe deficiency of existing composite and asymmetric membranes used in forward osmosis is the presence of unfavorable internal concentration polarization within the porous support layer that hinders both (i) separation (salt flux) and (ii) the performance (water flux). The double skin layers of the tailored membrane may mitigate the internal concentration polarization by preventing the salt and other solutes in the draw solution from penetrating into the membrane porous support. The prototype double-skinned cellulose acetate membrane displayed a water flux of 48.2 L·m−2·h−1 and lower reverse salt transport of 6.5 g·m−2·h−1 using 5.0 M MgCl2 as the draw solution in a forward osmosis process performed at 22 °C. This can be attributed to the effective salt rejection by the double skin layers and the low water transport resistance within the porous support layer. The prospects of utilizing the double-selective layer membranes may have potential application in forward osmosis for desalination. This study may help pave the way to improve the membrane design for the forward osmosis process. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901592d [article] Double - skinned forward osmosis membranes for reducing internal concentration polarization within the porous sublayer [texte imprimé] / Kai Yu Wang, Auteur ; Rui Chin Ong, Auteur ; Tai-Shung Chung, Auteur . - 2010 . - pp. 4824–4831. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 10 (Mai 2010) . - pp. 4824–4831 Mots-clés : Osmosis  Membranes Résumé : A scheme to fabricate forward osmosis membranes comprising a highly porous sublayer sandwiched between two selective skin layers via phase inversion was proposed. One severe deficiency of existing composite and asymmetric membranes used in forward osmosis is the presence of unfavorable internal concentration polarization within the porous support layer that hinders both (i) separation (salt flux) and (ii) the performance (water flux). The double skin layers of the tailored membrane may mitigate the internal concentration polarization by preventing the salt and other solutes in the draw solution from penetrating into the membrane porous support. The prototype double-skinned cellulose acetate membrane displayed a water flux of 48.2 L·m−2·h−1 and lower reverse salt transport of 6.5 g·m−2·h−1 using 5.0 M MgCl2 as the draw solution in a forward osmosis process performed at 22 °C. This can be attributed to the effective salt rejection by the double skin layers and the low water transport resistance within the porous support layer. The prospects of utilizing the double-selective layer membranes may have potential application in forward osmosis for desalination. This study may help pave the way to improve the membrane design for the forward osmosis process. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901592d

Highly water-soluble magnetic nanoparticles as novel draw solutes in forward osmosis for water reuse / Ming Ming Ling in Industrial & engineering chemistry research, Vol. 49 N° 12 (Juin 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 12 (Juin 2010) . - pp. 5869–5876 Titre : Highly water-soluble magnetic nanoparticles as novel draw solutes in forward osmosis for water reuse Type de document : texte imprimé Auteurs : Ming Ming Ling, Auteur ; Kai Yu Wang, Auteur ; Tai-Shung Chung, Auteur Année de publication : 2010 Article en page(s) : pp. 5869–5876 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Magnetic  nanoparticles  Highly  water-soluble  magnetic  nanoparticles Résumé : Highly hydrophilic magnetic nanoparticles have been molecularly designed. For the first time, the application of highly water-soluble magnetic nanoparticles as novel draw solutes in forward osmosis (FO) was systematically investigated. Magnetic nanoparticles functionalized by various groups were synthesized to explore the correlation between the surface chemistry of magnetic nanoparticles and the achieved osmolality. We verified that magnetic nanoparticles capped with polyacrylic acid can yield the highest driving force and subsequently highest water flux among others. The used magnetic nanoparticles can be captured by the magnetic field and recycled back into the stream as draw solutes in the FO process. In addition, magnetic nanoparticles of different diameters were also synthesized to study the effect of particles size on FO performance. We demonstrate that the engineering of surface hydrophilicity and magnetic nanoparticle size is crucial in the application of nanoparticles as draw solutes in FO. It is believed that magnetic nanoparticles will soon be extensively used in this area. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie100438x [article] Highly water-soluble magnetic nanoparticles as novel draw solutes in forward osmosis for water reuse [texte imprimé] / Ming Ming Ling, Auteur ; Kai Yu Wang, Auteur ; Tai-Shung Chung, Auteur . - 2010 . - pp. 5869–5876. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 12 (Juin 2010) . - pp. 5869–5876 Mots-clés : Magnetic  nanoparticles  Highly  water-soluble  magnetic  nanoparticles Résumé : Highly hydrophilic magnetic nanoparticles have been molecularly designed. For the first time, the application of highly water-soluble magnetic nanoparticles as novel draw solutes in forward osmosis (FO) was systematically investigated. Magnetic nanoparticles functionalized by various groups were synthesized to explore the correlation between the surface chemistry of magnetic nanoparticles and the achieved osmolality. We verified that magnetic nanoparticles capped with polyacrylic acid can yield the highest driving force and subsequently highest water flux among others. The used magnetic nanoparticles can be captured by the magnetic field and recycled back into the stream as draw solutes in the FO process. In addition, magnetic nanoparticles of different diameters were also synthesized to study the effect of particles size on FO performance. We demonstrate that the engineering of surface hydrophilicity and magnetic nanoparticle size is crucial in the application of nanoparticles as draw solutes in FO. It is believed that magnetic nanoparticles will soon be extensively used in this area. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie100438x

Mixed matrix PVDF hollow fiber membranes with nanoscale pores for desalination through direct contact membrane distillation / Kai Yu Wang in Industrial & engineering chemistry research, Vol. 48 N° 9 (Mai 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4474–4483 Titre : Mixed matrix PVDF hollow fiber membranes with nanoscale pores for desalination through direct contact membrane distillation Type de document : texte imprimé Auteurs : Kai Yu Wang, Auteur ; Suay Wei Foo, Auteur ; Tai-Shung Chung, Auteur Année de publication : 2009 Article en page(s) : pp. 4474–4483 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Direct  contact  membrane  distillation  Poly(vinylidene  fluoride  Hollow  fiber  membranes  Dry-jet  wet Résumé : Highly porous hydrophobic hollow fiber membranes with high porosity and sandwich trilayer structure were specially designed to meet the requirements of direct contact membrane distillation (DCMD). Poly(vinylidene fluoride) (PVDF)/Cloisite clay composite hollow fibers were fabricated based on the dry-jet wet phase inversion mechanism by using water as both the external and internal coagulants. Membrane void fraction of up to 90% can be produced to improve the fibers’ thermal insulation and reduce vapor transport resistance. The fiber inner surface was full of streaky pores with pore size less than 1.0 μm in diameter, while the pores on the fiber outer surface were much smaller, less than 50 nm in diameter. This demonstrates that membrane pores fabricated at a nanoscale can achieve high water vapor permeation flux with 100% salt rejection. For example, the fabricated PVDF/clay composite hollow fiber was tested by desalinating a 3.5 wt % NaCl solution and permeation flux as high as 79.2 kg/(m2·h) (calculated on the fiber outer diameter) was achieved at the inlet temperatures of 81.5/17.5 °C. The performance shows almost no decay during 220-h continuous tests. The addition of clay particles may enhance the tensile modulus and improve long-term stability compared to those fibers without particles. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8009704 [article] Mixed matrix PVDF hollow fiber membranes with nanoscale pores for desalination through direct contact membrane distillation [texte imprimé] / Kai Yu Wang, Auteur ; Suay Wei Foo, Auteur ; Tai-Shung Chung, Auteur . - 2009 . - pp. 4474–4483. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4474–4483 Mots-clés : Direct  contact  membrane  distillation  Poly(vinylidene  fluoride  Hollow  fiber  membranes  Dry-jet  wet Résumé : Highly porous hydrophobic hollow fiber membranes with high porosity and sandwich trilayer structure were specially designed to meet the requirements of direct contact membrane distillation (DCMD). Poly(vinylidene fluoride) (PVDF)/Cloisite clay composite hollow fibers were fabricated based on the dry-jet wet phase inversion mechanism by using water as both the external and internal coagulants. Membrane void fraction of up to 90% can be produced to improve the fibers’ thermal insulation and reduce vapor transport resistance. The fiber inner surface was full of streaky pores with pore size less than 1.0 μm in diameter, while the pores on the fiber outer surface were much smaller, less than 50 nm in diameter. This demonstrates that membrane pores fabricated at a nanoscale can achieve high water vapor permeation flux with 100% salt rejection. For example, the fabricated PVDF/clay composite hollow fiber was tested by desalinating a 3.5 wt % NaCl solution and permeation flux as high as 79.2 kg/(m2·h) (calculated on the fiber outer diameter) was achieved at the inlet temperatures of 81.5/17.5 °C. The performance shows almost no decay during 220-h continuous tests. The addition of clay particles may enhance the tensile modulus and improve long-term stability compared to those fibers without particles. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie8009704

Thin - film composite membranes and formation mechanism of thin - film layers on hydrophilic cellulose acetate propionate substrates for forward osmosis processes / Xue Li in Industrial & engineering chemistry research, Vol. 51 N° 30 (Août 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 30 (Août 2012) . - pp. 10039–10050 Titre : Thin - film composite membranes and formation mechanism of thin - film layers on hydrophilic cellulose acetate propionate substrates for forward osmosis processes Type de document : texte imprimé Auteurs : Xue Li, Auteur ; Kai Yu Wang, Auteur ; Bradley Helmer, Auteur Année de publication : 2012 Article en page(s) : pp. 10039–10050 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Composite  membranes  Hydrophilic Résumé : For the first time, the potential of using hydrophilic cellulose acetate propionate (CAP) as microporous substrates for the fabrication of thin-film composite (TFC) forward osmosis (FO) membranes has been explored. Two types of TFC flat sheet membranes with well-designed substrate structures were prepared. The CAP-TFC membranes show very low Js/Jw ratios (i.e., the ratio of reverse draw solute flux to water flux) of about 0.05 g/L with reasonably high water fluxes under the pressure-retarded osmosis (PRO) mode using 2 M NaCl as the draw solution and deionized water as the feed. When using model seawater as the feed, the water flux is about 12.3 LMH which is comparable to the best in the literature. These results, combined with positron annihilation spectroscopy (PAS) data, confirm the hypothesis that a finger-like morphology in the substrate is not crucial to the performance of TFC FO membranes. Moreover, the surface and skin morphology of the substrate may play essential roles in the formation of the polyamide layer as well as its perfectness and FO performance. A dynamic scheme to elucidate the evolution of forming the globular and worm-like structure during the interfacial polymerization has been proposed. Substrates with larger pores and broader distribution may facilitate rapid migration of amine molecules, induce more complicated convection at the interface, and enlarge reaction contact area, resulting in a rougher but more compact polyamide layer in the TFC membranes, while smaller surface pores of substrate favor simple convection at the interface during the interfacial reaction, producing nascent cross-linked films with smaller domain sizes, smoother and less dense structure, and less defects. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie2027052 [article] Thin - film composite membranes and formation mechanism of thin - film layers on hydrophilic cellulose acetate propionate substrates for forward osmosis processes [texte imprimé] / Xue Li, Auteur ; Kai Yu Wang, Auteur ; Bradley Helmer, Auteur . - 2012 . - pp. 10039–10050. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 30 (Août 2012) . - pp. 10039–10050 Mots-clés : Composite  membranes  Hydrophilic Résumé : For the first time, the potential of using hydrophilic cellulose acetate propionate (CAP) as microporous substrates for the fabrication of thin-film composite (TFC) forward osmosis (FO) membranes has been explored. Two types of TFC flat sheet membranes with well-designed substrate structures were prepared. The CAP-TFC membranes show very low Js/Jw ratios (i.e., the ratio of reverse draw solute flux to water flux) of about 0.05 g/L with reasonably high water fluxes under the pressure-retarded osmosis (PRO) mode using 2 M NaCl as the draw solution and deionized water as the feed. When using model seawater as the feed, the water flux is about 12.3 LMH which is comparable to the best in the literature. These results, combined with positron annihilation spectroscopy (PAS) data, confirm the hypothesis that a finger-like morphology in the substrate is not crucial to the performance of TFC FO membranes. Moreover, the surface and skin morphology of the substrate may play essential roles in the formation of the polyamide layer as well as its perfectness and FO performance. A dynamic scheme to elucidate the evolution of forming the globular and worm-like structure during the interfacial polymerization has been proposed. Substrates with larger pores and broader distribution may facilitate rapid migration of amine molecules, induce more complicated convection at the interface, and enlarge reaction contact area, resulting in a rougher but more compact polyamide layer in the TFC membranes, while smaller surface pores of substrate favor simple convection at the interface during the interfacial reaction, producing nascent cross-linked films with smaller domain sizes, smoother and less dense structure, and less defects. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie2027052