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Atrazine degradation by in situ electrochemically generated ozone / Ysrael Marrero Vera in Chemical engineering journal, Vol. 155 N° 3 (Decembre 2009) 

Public ISBD [article]  in Chemical engineering journal > Vol. 155 N° 3 (Decembre 2009) . - pp. 691-697 Titre : Atrazine degradation by in situ electrochemically generated ozone Type de document : texte imprimé Auteurs : Ysrael Marrero Vera, Auteur ; Roberto José De Carvalho, Auteur ; Mauricio Leonardo Torem, Auteur Année de publication : 2010 Article en page(s) : pp. 691-697 Note générale : Génie Chimique Langues : Anglais (eng) Mots-clés : Groundwater  Remediation  PbO2  electrode  Electrochemistry  Ozone  Atrazine Index. décimale : 660 Résumé : A study on the evaluation of the effectiveness of atrazine degradation by in situ electrochemically generated ozone was conducted. Ti/β-PbO2 electrodes were used as anodes for the ozone production. The rate of ozone generation, the ozone saturation concentration and the atrazine degradation rate increased with increasing current density. The maximum rate was close to 40 mg h−1, the dissolved ozone concentration was 1.6 mg L−1 for a current density of 1.5 kA m−2 and the electrochemical efficiency was around 6%. The degradation data followed a pseudo first-order kinetic. The values of the rate constants were 6.2 × 10−3, 8.8 × 10−3, and 1.21 × 10−2 min−1 for 0.5, 1.0, and 1.5 kA m−2, respectively. The degradation took place by the combined oxidation with O3 and radical dotOH generated at the Ti/β-PbO2 anode surface and by ozone decomposition. The rate was electrochemically controlled up to approximately 90% of degradation and by mass transfer thereafter. The degradation mechanism was comprised mainly by dealkylation followed by a slow dechlorination of the atrazine molecule. Continuous atrazine degradation tests were conducted in a column containing a porous medium with the purpose of determining whether the in situ electrochemical production of the oxidants radical dotOH/O3 is effective at reducing the atrazine concentration in the transported flux across the bed. The work demonstrates the potential applicability of the continuous system for in situ atrazine degradation in underground waters, and provides a basis for the future development of this technology. DEWEY : 660 ISSN : 1385-8947 En ligne : http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TFJ-4X5JRBR-1&_user=6 [...] [article] Atrazine degradation by in situ electrochemically generated ozone [texte imprimé] / Ysrael Marrero Vera, Auteur ; Roberto José De Carvalho, Auteur ; Mauricio Leonardo Torem, Auteur . - 2010 . - pp. 691-697. Génie Chimique Langues : Anglais (eng) in Chemical engineering journal > Vol. 155 N° 3 (Decembre 2009) . - pp. 691-697 Mots-clés : Groundwater  Remediation  PbO2  electrode  Electrochemistry  Ozone  Atrazine Index. décimale : 660 Résumé : A study on the evaluation of the effectiveness of atrazine degradation by in situ electrochemically generated ozone was conducted. Ti/β-PbO2 electrodes were used as anodes for the ozone production. The rate of ozone generation, the ozone saturation concentration and the atrazine degradation rate increased with increasing current density. The maximum rate was close to 40 mg h−1, the dissolved ozone concentration was 1.6 mg L−1 for a current density of 1.5 kA m−2 and the electrochemical efficiency was around 6%. The degradation data followed a pseudo first-order kinetic. The values of the rate constants were 6.2 × 10−3, 8.8 × 10−3, and 1.21 × 10−2 min−1 for 0.5, 1.0, and 1.5 kA m−2, respectively. The degradation took place by the combined oxidation with O3 and radical dotOH generated at the Ti/β-PbO2 anode surface and by ozone decomposition. The rate was electrochemically controlled up to approximately 90% of degradation and by mass transfer thereafter. The degradation mechanism was comprised mainly by dealkylation followed by a slow dechlorination of the atrazine molecule. Continuous atrazine degradation tests were conducted in a column containing a porous medium with the purpose of determining whether the in situ electrochemical production of the oxidants radical dotOH/O3 is effective at reducing the atrazine concentration in the transported flux across the bed. The work demonstrates the potential applicability of the continuous system for in situ atrazine degradation in underground waters, and provides a basis for the future development of this technology. DEWEY : 660 ISSN : 1385-8947 En ligne : http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TFJ-4X5JRBR-1&_user=6 [...]

Evaluation of equilibrium, kinetic and thermodynamic parameters for biosorption of nickel(II) ions onto bacteria strain, Rhodococcus opacus / Javier Enrique Basurco Cayllahua in Minerals engineering, Vol. 22 N° 15 (Décembre 2009) 

Public ISBD [article]  in Minerals engineering > Vol. 22 N° 15 (Décembre 2009) . - pp. 1318–1325 Titre : Evaluation of equilibrium, kinetic and thermodynamic parameters for biosorption of nickel(II) ions onto bacteria strain, Rhodococcus opacus Type de document : texte imprimé Auteurs : Javier Enrique Basurco Cayllahua, Auteur ; Roberto José De Carvalho, Auteur ; Mauricio Leonardo Torem, Auteur Année de publication : 2010 Article en page(s) : pp. 1318–1325 Note générale : Génie Minier Langues : Anglais (eng) Mots-clés : Biotechnology  Environmental  Nickel(II)  Bacteria  (Rhodococcus  opacus) Résumé : The present study explores the ability of Rhodococcus opacus bacteria strain for the removal of nickel(II) under different experimental conditions. The effects of relevant parameters such as solution pH, biomass loading, ionic strength, and temperature on nickel(II) biosorption capacity were evaluated. Although the tests were carried out using synthetic solutions, the results are representative of typical waste effluents from chemical, dyestuffs, battery manufacture, porcelain enameling, metallurgical industries and electroplating circuits. The sorption data followed the Langmuir, Freundlich, Temkin, Dubinin–Radushkevich, and Sips isotherms. The maximum sorption capacity was found to be 7.63 mg g−1 at pH 5. Thermodynamic parameters have also been evaluated and the results show that the sorption process was spontaneous and endothermic in nature. The dynamics of the sorption process were studied and the values of rate constants for different kinetic models were calculated. The activation energy of biosorption (Ea) was determined as 12.56 kJ mol−1 using the Arrhenius equation. DEWEY : 622 ISSN : 0892-6875 En ligne : http://www.sciencedirect.com/science/article/pii/S0892687509001915 [article] Evaluation of equilibrium, kinetic and thermodynamic parameters for biosorption of nickel(II) ions onto bacteria strain, Rhodococcus opacus [texte imprimé] / Javier Enrique Basurco Cayllahua, Auteur ; Roberto José De Carvalho, Auteur ; Mauricio Leonardo Torem, Auteur . - 2010 . - pp. 1318–1325. Génie Minier Langues : Anglais (eng) in Minerals engineering > Vol. 22 N° 15 (Décembre 2009) . - pp. 1318–1325 Mots-clés : Biotechnology  Environmental  Nickel(II)  Bacteria  (Rhodococcus  opacus) Résumé : The present study explores the ability of Rhodococcus opacus bacteria strain for the removal of nickel(II) under different experimental conditions. The effects of relevant parameters such as solution pH, biomass loading, ionic strength, and temperature on nickel(II) biosorption capacity were evaluated. Although the tests were carried out using synthetic solutions, the results are representative of typical waste effluents from chemical, dyestuffs, battery manufacture, porcelain enameling, metallurgical industries and electroplating circuits. The sorption data followed the Langmuir, Freundlich, Temkin, Dubinin–Radushkevich, and Sips isotherms. The maximum sorption capacity was found to be 7.63 mg g−1 at pH 5. Thermodynamic parameters have also been evaluated and the results show that the sorption process was spontaneous and endothermic in nature. The dynamics of the sorption process were studied and the values of rate constants for different kinetic models were calculated. The activation energy of biosorption (Ea) was determined as 12.56 kJ mol−1 using the Arrhenius equation. DEWEY : 622 ISSN : 0892-6875 En ligne : http://www.sciencedirect.com/science/article/pii/S0892687509001915