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Polyphenol polymerization by horseradish peroxidase for metal adsorption studies / Hidetaka Kawakita 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. 4440–4444 Titre : Polyphenol polymerization by horseradish peroxidase for metal adsorption studies Type de document : texte imprimé Auteurs : Hidetaka Kawakita, Auteur ; Kohshi Hamamoto, Auteur ; Keisuke Ohto, Auteur Année de publication : 2009 Article en page(s) : pp. 4440–4444 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : Polyphenol  Horseradish  peroxidase  reaction  Fourier  transform  infrared  spectrometry  Size-exclusion  chromatography  Metal  adsorption Résumé : Four phenol derivatives (m-cresol, 3-methylcatechol, 4-methylcatechol, and 4-ethylcatechol) were polymerized using the horseradish peroxidase reaction, and their metal adsorption capabilities were studied. Fourier transform infrared (FT-IR) spectrometry and size-exclusion chromatography indicated that the phenol monomers polymerized to give polyphenols having molecular weights from 700 to 3000. During metal adsorption studies, poly(3-methylcatechol) adsorbed copper ions at 100% in a solution of pH 5.0, whereas poly(m-cresol) failed to adsorb any copper ions. Gold ions selectively adsorbed to poly(4-ethylcatechol) in acid media and formed gold particles via reduction of the polyphenol. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800830m [article] Polyphenol polymerization by horseradish peroxidase for metal adsorption studies [texte imprimé] / Hidetaka Kawakita, Auteur ; Kohshi Hamamoto, Auteur ; Keisuke Ohto, Auteur . - 2009 . - pp. 4440–4444. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 9 (Mai 2009) . - pp. 4440–4444 Mots-clés : Polyphenol  Horseradish  peroxidase  reaction  Fourier  transform  infrared  spectrometry  Size-exclusion  chromatography  Metal  adsorption Résumé : Four phenol derivatives (m-cresol, 3-methylcatechol, 4-methylcatechol, and 4-ethylcatechol) were polymerized using the horseradish peroxidase reaction, and their metal adsorption capabilities were studied. Fourier transform infrared (FT-IR) spectrometry and size-exclusion chromatography indicated that the phenol monomers polymerized to give polyphenols having molecular weights from 700 to 3000. During metal adsorption studies, poly(3-methylcatechol) adsorbed copper ions at 100% in a solution of pH 5.0, whereas poly(m-cresol) failed to adsorb any copper ions. Gold ions selectively adsorbed to poly(4-ethylcatechol) in acid media and formed gold particles via reduction of the polyphenol. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie800830m

Reduction of gold ions to gold particles by reusable soluble poly (tyramine) polymerized by horseradish peroxidase / Hidetaka Kawakita in Industrial & engineering chemistry research, Vol. 49 N° 22 (Novembre 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 22 (Novembre 2010) . - pp. 11582-11586 Titre : Reduction of gold ions to gold particles by reusable soluble poly (tyramine) polymerized by horseradish peroxidase Type de document : texte imprimé Auteurs : Hidetaka Kawakita, Auteur ; Yuko Yoshimura, Auteur ; Keisuke Ohto, Auteur Année de publication : 2011 Article en page(s) : pp. 11582-11586 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Gold  Ions Résumé : A novel recovery method is proposed for gold ions using poly(tyramine), which is reductive and has easily manipulated solubility. Tyramine, which has phenol and amino groups, was polymerized using horseradish peroxidase. When the HCl concentration in solution was increased, poly(tyramine) solubility decreased, probably due to chloride ion coordination with the poly(tyramine) amino group. Poly(tyramine) was highly soluble at pH <4.0 in the pH region. When the polymer was reacted with gold ion solution in HCl for 48 h, the maximum amount of gold ions obtained was 4.0 mol/kg in a two-step reduction isotherm curve. Filtered reduced gold particles with poly(tyramine) were immersed in 0.1 M HCl solution, resulting in dissolution of the poly(tyramine), and the gold particles were then easily recovered by filtration. Adjusting the pH of the filtered solution to 7.5 allowed recovery of the poly(tyramine) as a precipitate, which could then be reused to reduce further gold ions. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie100127g [article] Reduction of gold ions to gold particles by reusable soluble poly (tyramine) polymerized by horseradish peroxidase [texte imprimé] / Hidetaka Kawakita, Auteur ; Yuko Yoshimura, Auteur ; Keisuke Ohto, Auteur . - 2011 . - pp. 11582-11586. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 22 (Novembre 2010) . - pp. 11582-11586 Mots-clés : Gold  Ions Résumé : A novel recovery method is proposed for gold ions using poly(tyramine), which is reductive and has easily manipulated solubility. Tyramine, which has phenol and amino groups, was polymerized using horseradish peroxidase. When the HCl concentration in solution was increased, poly(tyramine) solubility decreased, probably due to chloride ion coordination with the poly(tyramine) amino group. Poly(tyramine) was highly soluble at pH <4.0 in the pH region. When the polymer was reacted with gold ion solution in HCl for 48 h, the maximum amount of gold ions obtained was 4.0 mol/kg in a two-step reduction isotherm curve. Filtered reduced gold particles with poly(tyramine) were immersed in 0.1 M HCl solution, resulting in dissolution of the poly(tyramine), and the gold particles were then easily recovered by filtration. Adjusting the pH of the filtered solution to 7.5 allowed recovery of the poly(tyramine) as a precipitate, which could then be reused to reduce further gold ions. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie100127g

Selective recovery of precious metals from acidic leach liquor of circuit boards of spent mobile phones using chemically modified persimmon tannin gel / Manju Gurung in Industrial & engineering chemistry research, Vol. 51 N° 37 (Septembre 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 37 (Septembre 2012) . - pp. 11901–11913 Titre : Selective recovery of precious metals from acidic leach liquor of circuit boards of spent mobile phones using chemically modified persimmon tannin gel Type de document : texte imprimé Auteurs : Manju Gurung, Auteur ; Birendra Babu Adhikari, Auteur ; Hidetaka Kawakita, Auteur Année de publication : 2012 Article en page(s) : pp. 11901–11913 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Precious  metals  Acidic  leach Résumé : A tannin-based novel adsorbent, named “BTU-PT gel”, was prepared by immobilizing bisthiourea (BTU) ligand on persimmon tannin (PT) extract. The adsorption behaviors of precious metal ions along with other coexisting base metal ions onto BTU-PT gel were studied by batch and continuous column methods. The gel exhibited remarkable selectivity for precious metal ions such as Au(III), Pd(II), and Pt(IV) over base metal ions such as Cu(II), Fe(III), Ni(II), and Zn(II) in 1–5 mol dm–3 hydrochloric acid. The adsorption of precious metal ions on the present gel was found to obey the typical monolayer type of Langmuir model, and the maximum adsorption capacity of the adsorbent was evaluated as 5.18 mol kg–1 for Au(III), 1.80 mol kg–1 for Pd(II), and 0.67 mol kg–1 for Pt(IV). Combination of ion exchange, electrostatic interaction, and coordination through the thiocarbonyl group is the mechanism of adsorption of precious metals on BTU-PT gel. In the case of Au(III) adsorption, the adsorbed species was simultaneously reduced to elemental gold by abundant polyphenolic groups of the tannin matrix. Elution by using acidothiourea solution in continuous column experiment recovered the adsorbed precious metals almost quantitatively. The results of a potential reusability test of the gel for consecutive adsorption and elution cycles by continuous column experiment indicated that the gel was stable and regenerated with undiminished metal uptake capacity up to five cycles. The real time applicability of the adsorbent for the recovery of precious metals from real industrial liquor was evaluated from actual acidic leach liquor of printed circuit boards of spent mobile phones. The gel selectively adsorbed precious metal species but exhibited negligible affinity toward base metals present in the leach liquor. The BTU-PT gel is a potential adsorbent for selective recovery of precious metals from acidic leachate of spent mobile phones containing elevated concentrations of base metals. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie3009023 [article] Selective recovery of precious metals from acidic leach liquor of circuit boards of spent mobile phones using chemically modified persimmon tannin gel [texte imprimé] / Manju Gurung, Auteur ; Birendra Babu Adhikari, Auteur ; Hidetaka Kawakita, Auteur . - 2012 . - pp. 11901–11913. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 37 (Septembre 2012) . - pp. 11901–11913 Mots-clés : Precious  metals  Acidic  leach Résumé : A tannin-based novel adsorbent, named “BTU-PT gel”, was prepared by immobilizing bisthiourea (BTU) ligand on persimmon tannin (PT) extract. The adsorption behaviors of precious metal ions along with other coexisting base metal ions onto BTU-PT gel were studied by batch and continuous column methods. The gel exhibited remarkable selectivity for precious metal ions such as Au(III), Pd(II), and Pt(IV) over base metal ions such as Cu(II), Fe(III), Ni(II), and Zn(II) in 1–5 mol dm–3 hydrochloric acid. The adsorption of precious metal ions on the present gel was found to obey the typical monolayer type of Langmuir model, and the maximum adsorption capacity of the adsorbent was evaluated as 5.18 mol kg–1 for Au(III), 1.80 mol kg–1 for Pd(II), and 0.67 mol kg–1 for Pt(IV). Combination of ion exchange, electrostatic interaction, and coordination through the thiocarbonyl group is the mechanism of adsorption of precious metals on BTU-PT gel. In the case of Au(III) adsorption, the adsorbed species was simultaneously reduced to elemental gold by abundant polyphenolic groups of the tannin matrix. Elution by using acidothiourea solution in continuous column experiment recovered the adsorbed precious metals almost quantitatively. The results of a potential reusability test of the gel for consecutive adsorption and elution cycles by continuous column experiment indicated that the gel was stable and regenerated with undiminished metal uptake capacity up to five cycles. The real time applicability of the adsorbent for the recovery of precious metals from real industrial liquor was evaluated from actual acidic leach liquor of printed circuit boards of spent mobile phones. The gel selectively adsorbed precious metal species but exhibited negligible affinity toward base metals present in the leach liquor. The BTU-PT gel is a potential adsorbent for selective recovery of precious metals from acidic leachate of spent mobile phones containing elevated concentrations of base metals. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie3009023