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Preparation of thiocyanate - retaining tannin gel for adsorption recovery of palladium from strong hydrochloric acid solutions / Shintaro Morisada in Industrial & engineering chemistry research, Vol. 50 N° 22 (Novembre 2011) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 50 N° 22 (Novembre 2011) . - pp. 12366–12371 Titre : Preparation of thiocyanate - retaining tannin gel for adsorption recovery of palladium from strong hydrochloric acid solutions Type de document : texte imprimé Auteurs : Shintaro Morisada, Auteur ; Yoen-Ho Kim, Auteur ; Shinpei Yakuwa, Auteur Année de publication : 2012 Article en page(s) : pp. 12366–12371 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Adsorption  Preparation Résumé : A tannin gel (TG) synthesized from condensed tannin molecules has a remarkable ability to adsorb various metal ions in aqueous solutions. In the present study, we have introduced thiocyanate ions (SCN–) into the TG by adsorption process in acidic thiocyanate solutions to improve its adsorbability for palladium ion, Pd(II). To determine the optimum conditions for preparing the SCN–-retaining tannin gel (SCN-TG), we have investigated the introduction mechanism of SCN– into the TG at 298 K and HCl concentrations less than or equal to 1 M, where the decomposition of SCN– can be negligible. The adsorption amount of SCN– onto the TG increased with increasing HCl concentration, indicating that SCN– is adsorbed onto the TG through the electrostatic attraction between anionic SCN– and the protonated hydroxy groups in the TG at higher HCl concentrations. Using the resultant SCN-TG and the TG, we have conducted the Pd(II) adsorption experiment at molar-level concentrations of HCl and found that the SCN-TG can adsorb Pd(II) efficiently, whereas the TG adsorbs almost no Pd(II). Besides, the adsorbability of the SCN-TG for Pd(II) decreased only slightly with increasing HCl concentration up to at least 5 M. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=24745707 [article] Preparation of thiocyanate - retaining tannin gel for adsorption recovery of palladium from strong hydrochloric acid solutions [texte imprimé] / Shintaro Morisada, Auteur ; Yoen-Ho Kim, Auteur ; Shinpei Yakuwa, Auteur . - 2012 . - pp. 12366–12371. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 50 N° 22 (Novembre 2011) . - pp. 12366–12371 Mots-clés : Adsorption  Preparation Résumé : A tannin gel (TG) synthesized from condensed tannin molecules has a remarkable ability to adsorb various metal ions in aqueous solutions. In the present study, we have introduced thiocyanate ions (SCN–) into the TG by adsorption process in acidic thiocyanate solutions to improve its adsorbability for palladium ion, Pd(II). To determine the optimum conditions for preparing the SCN–-retaining tannin gel (SCN-TG), we have investigated the introduction mechanism of SCN– into the TG at 298 K and HCl concentrations less than or equal to 1 M, where the decomposition of SCN– can be negligible. The adsorption amount of SCN– onto the TG increased with increasing HCl concentration, indicating that SCN– is adsorbed onto the TG through the electrostatic attraction between anionic SCN– and the protonated hydroxy groups in the TG at higher HCl concentrations. Using the resultant SCN-TG and the TG, we have conducted the Pd(II) adsorption experiment at molar-level concentrations of HCl and found that the SCN-TG can adsorb Pd(II) efficiently, whereas the TG adsorbs almost no Pd(II). Besides, the adsorbability of the SCN-TG for Pd(II) decreased only slightly with increasing HCl concentration up to at least 5 M. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=24745707

Temperature - swing adsorption of proteins in water using cationic copolymer - grafted silica particles / Shintaro Morisada in Industrial & engineering chemistry research, Vol. 50 N° 22 (Novembre 2011) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 50 N° 22 (Novembre 2011) . - pp. 12358–12365 Titre : Temperature - swing adsorption of proteins in water using cationic copolymer - grafted silica particles Type de document : texte imprimé Auteurs : Shintaro Morisada, Auteur ; Ken-ichiro Namazuda, Auteur ; Shitoka Suzuki, Auteur Année de publication : 2012 Article en page(s) : pp. 12358–12365 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Adsorption  Copolymer Résumé : We have prepared silica particles grafted with poly(N-isopropylacrylamide) (PNIPA) copolymers as adsorbent for the temperature-swing adsorption of bovine serum albumin (BSA) in water, where vinylbenzyl trimethylammonium chloride (VBTA), 2-(dimethylamino)ethyl methacrylate (DMAEMA), or N,N-dimethylacrylamide (DMAA) was employed as a comonomer. The surface potentials of PNIPA-grafted and P(NIPA-co-DMAA)-grafted silica particles in water at 298 and 313 K were negative, while those of P(NIPA-co-VBTA)-grafted silica particle were positive, because VBTA is a quaternary ammonium salt and positively charged in aqueous solutions. As for the P(NIPA-co-DMAEMA)-grafted silica particle, the surface potential changed from positive to near zero with increasing temperature from 298 K to 313 K. This may be because the coil-to-globule transition of grafted copolymers leads to the dehydration and deprotonation of DMAEMA group, which is a tertiary amine and can be positively charged only in the aqueous phase. Although PNIPA-grafted and P(NIPA-co-DMAA)-grafted silica particles failed to adsorb BSA, P(NIPA-co-VBTA)-grafted and P(NIPA-co-DMAEMA)-grafted silica particles adsorbed BSA, indicating that BSA is adsorbed by the electrostatic attraction between the negatively charged BSA and the positively charged copolymers on the silica surface. Moreover, P(NIPA-co-VBTA)-grafted and P(NIPA-co-DMAEMA)-grafted silica particles repeatedly adsorbed BSA at 298 K and desorbed some of the preadsorbed BSA at 313 K via the temperature-swing operation. This BSA desorption may result from the decrease in the number of the positively charged groups accessible to BSA due to the coil-to-globule transition of the grafted copolymers with increasing temperature. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie200779w [article] Temperature - swing adsorption of proteins in water using cationic copolymer - grafted silica particles [texte imprimé] / Shintaro Morisada, Auteur ; Ken-ichiro Namazuda, Auteur ; Shitoka Suzuki, Auteur . - 2012 . - pp. 12358–12365. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 50 N° 22 (Novembre 2011) . - pp. 12358–12365 Mots-clés : Adsorption  Copolymer Résumé : We have prepared silica particles grafted with poly(N-isopropylacrylamide) (PNIPA) copolymers as adsorbent for the temperature-swing adsorption of bovine serum albumin (BSA) in water, where vinylbenzyl trimethylammonium chloride (VBTA), 2-(dimethylamino)ethyl methacrylate (DMAEMA), or N,N-dimethylacrylamide (DMAA) was employed as a comonomer. The surface potentials of PNIPA-grafted and P(NIPA-co-DMAA)-grafted silica particles in water at 298 and 313 K were negative, while those of P(NIPA-co-VBTA)-grafted silica particle were positive, because VBTA is a quaternary ammonium salt and positively charged in aqueous solutions. As for the P(NIPA-co-DMAEMA)-grafted silica particle, the surface potential changed from positive to near zero with increasing temperature from 298 K to 313 K. This may be because the coil-to-globule transition of grafted copolymers leads to the dehydration and deprotonation of DMAEMA group, which is a tertiary amine and can be positively charged only in the aqueous phase. Although PNIPA-grafted and P(NIPA-co-DMAA)-grafted silica particles failed to adsorb BSA, P(NIPA-co-VBTA)-grafted and P(NIPA-co-DMAEMA)-grafted silica particles adsorbed BSA, indicating that BSA is adsorbed by the electrostatic attraction between the negatively charged BSA and the positively charged copolymers on the silica surface. Moreover, P(NIPA-co-VBTA)-grafted and P(NIPA-co-DMAEMA)-grafted silica particles repeatedly adsorbed BSA at 298 K and desorbed some of the preadsorbed BSA at 313 K via the temperature-swing operation. This BSA desorption may result from the decrease in the number of the positively charged groups accessible to BSA due to the coil-to-globule transition of the grafted copolymers with increasing temperature. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie200779w