Documents disponibles écrits par cet auteur

Modified chitosan hydrogels for the removal of acid dyes at high pH / Dan Xu in Industrial & engineering chemistry research, Vol. 50 N° 10 (Mai 2011) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 50 N° 10 (Mai 2011) . - pp. 6343-6346 Titre : Modified chitosan hydrogels for the removal of acid dyes at high pH : modification and regeneration Type de document : texte imprimé Auteurs : Dan Xu, Auteur ; San Hein, Auteur ; Sunsun Leslie Loo, Auteur Année de publication : 2011 Article en page(s) : pp. 6343-6346 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : pH  Acid  dye Résumé : Chitosan hydrogels were modified with (NH4)2SO4 solution using two methods and were tested in adsorbing acid dyes at a high pH of 8.2. The modified chitosan presented significantly improved adsorption capacities toward two dye samples: acid orange 7 and acid red 18. Specifically, these capacities were about 7.4 and 14.4 times higher than those of native chitosan, respectively, at the same conditions. The ion-exchange mechanism of the dye adsorption on the modified sample was proposed and verified by FTIR spectra. Regeneration experiments showed that the dye exhausted sample can be almost completely regenerated with NaOH solution while the capacity was largely retained even after 20 cycles of adsorption-regeneration-modification processes. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=24158929 [article] Modified chitosan hydrogels for the removal of acid dyes at high pH : modification and regeneration [texte imprimé] / Dan Xu, Auteur ; San Hein, Auteur ; Sunsun Leslie Loo, Auteur . - 2011 . - pp. 6343-6346. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 50 N° 10 (Mai 2011) . - pp. 6343-6346 Mots-clés : pH  Acid  dye Résumé : Chitosan hydrogels were modified with (NH4)2SO4 solution using two methods and were tested in adsorbing acid dyes at a high pH of 8.2. The modified chitosan presented significantly improved adsorption capacities toward two dye samples: acid orange 7 and acid red 18. Specifically, these capacities were about 7.4 and 14.4 times higher than those of native chitosan, respectively, at the same conditions. The ion-exchange mechanism of the dye adsorption on the modified sample was proposed and verified by FTIR spectra. Regeneration experiments showed that the dye exhausted sample can be almost completely regenerated with NaOH solution while the capacity was largely retained even after 20 cycles of adsorption-regeneration-modification processes. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=24158929

Rubbery polymer − inorganic nanocomposite membranes / Ben Li in Industrial & engineering chemistry research, Vol. 49 N° 24 (Décembre 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 24 (Décembre 2010) . - pp. 12444–12451 Titre : Rubbery polymer − inorganic nanocomposite membranes : free volume characteristics on separation property Type de document : texte imprimé Auteurs : Ben Li, Auteur ; Dan Xu, Auteur ; Xiongfei Zhang, Auteur Année de publication : 2011 Article en page(s) : pp. 12444–12451 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Nanocomposite  Polymer  inorganic Résumé : The rational design of polymer−inorganic nanocomposite membranes relies heavily on the precise insight and elaborate control of the interface. Presently, the direct exploration of the hierarchical structure of nanocomposite membranes still remains elusive. In the present study, we propose a facile and generic methodology to quantitatively probe the interfacial structure by complementary positron annihilation lifetime spectroscopy (PALS) and molecular dynamics simulation (MDS) techniques. MDS is used to acquire the molecular level information such as the polymer−inorganic interface interaction energy, chain mobility within the nanocomposite membranes, whereas PALS is used to acquire the free volume characteristics of the nanocomposite membranes. As proof-of-principle, we choose anisotropic inorganic nanotube embedded rubbery polymer membrane as a model, which generates the interface between soft polymer and rigid inorganic. PALS reveals that incorporation of titanate nanotubes (TNTs) narrows the free volume pore radius distribution of the membranes. MDS indicates that the segmental chain mobility in the vicinity of the polymer−inorganic interface is substantially restrained, which creates numerous nanosized voids for molecular transport, and dramatically enhances the fractional free volume (FFV) of the membranes. Quite interestingly, it was found that the rubbery membranes can also exhibit simultaneously increased permeability and membrane selectivity, and this unusual phenomenon was tentatively elucidated by relating the separation properties to the free volume characteristics of the membranes. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie101142b [article] Rubbery polymer − inorganic nanocomposite membranes : free volume characteristics on separation property [texte imprimé] / Ben Li, Auteur ; Dan Xu, Auteur ; Xiongfei Zhang, Auteur . - 2011 . - pp. 12444–12451. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 24 (Décembre 2010) . - pp. 12444–12451 Mots-clés : Nanocomposite  Polymer  inorganic Résumé : The rational design of polymer−inorganic nanocomposite membranes relies heavily on the precise insight and elaborate control of the interface. Presently, the direct exploration of the hierarchical structure of nanocomposite membranes still remains elusive. In the present study, we propose a facile and generic methodology to quantitatively probe the interfacial structure by complementary positron annihilation lifetime spectroscopy (PALS) and molecular dynamics simulation (MDS) techniques. MDS is used to acquire the molecular level information such as the polymer−inorganic interface interaction energy, chain mobility within the nanocomposite membranes, whereas PALS is used to acquire the free volume characteristics of the nanocomposite membranes. As proof-of-principle, we choose anisotropic inorganic nanotube embedded rubbery polymer membrane as a model, which generates the interface between soft polymer and rigid inorganic. PALS reveals that incorporation of titanate nanotubes (TNTs) narrows the free volume pore radius distribution of the membranes. MDS indicates that the segmental chain mobility in the vicinity of the polymer−inorganic interface is substantially restrained, which creates numerous nanosized voids for molecular transport, and dramatically enhances the fractional free volume (FFV) of the membranes. Quite interestingly, it was found that the rubbery membranes can also exhibit simultaneously increased permeability and membrane selectivity, and this unusual phenomenon was tentatively elucidated by relating the separation properties to the free volume characteristics of the membranes. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie101142b

The fixed-bed study of dye removal on chitosan beads at high pH / Dan Xu ; San Hein ; Sunsun Leslie Loo ; Kean Wang in Industrial & engineering chemistry research, Vol. 47 n°22 (Novembre 2008) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 47 n°22 (Novembre 2008) . - p. 8796–8800 Titre : The fixed-bed study of dye removal on chitosan beads at high pH Type de document : texte imprimé Auteurs : Dan Xu, Auteur ; San Hein, Auteur ; Sunsun Leslie Loo, Auteur ; Kean Wang, Auteur Année de publication : 2008 Article en page(s) : p. 8796–8800 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Beads  High  pH Résumé : Chitosan hydrogel beads were modified with ammonium sulfate to remove a dye (Acid Orange-7) in aqueous solutions at pH 8.2. The modified beads present much higher sorption capacity than the native beads in the basic solution. The sorption equilibrium was measured in a batch adsorber, and kinetics was investigated in a fixed bed rig. The breakthrough curves were found to be J-shaped in general and were modeled by the Wheeler−Jonas equation with a two-segmented approach. Analysis shows that the kinetics is controlled by film resistance and intraparticle diffusion in each segment, respectively. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800387z [article] The fixed-bed study of dye removal on chitosan beads at high pH [texte imprimé] / Dan Xu, Auteur ; San Hein, Auteur ; Sunsun Leslie Loo, Auteur ; Kean Wang, Auteur . - 2008 . - p. 8796–8800. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 n°22 (Novembre 2008) . - p. 8796–8800 Mots-clés : Beads  High  pH Résumé : Chitosan hydrogel beads were modified with ammonium sulfate to remove a dye (Acid Orange-7) in aqueous solutions at pH 8.2. The modified beads present much higher sorption capacity than the native beads in the basic solution. The sorption equilibrium was measured in a batch adsorber, and kinetics was investigated in a fixed bed rig. The breakthrough curves were found to be J-shaped in general and were modeled by the Wheeler−Jonas equation with a two-segmented approach. Analysis shows that the kinetics is controlled by film resistance and intraparticle diffusion in each segment, respectively. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800387z