Documents disponibles écrits par cet auteur

Monitoring the ozonation of phenol solutions at constant pH by different methods / Edgardo M. Contreras in Industrial & engineering chemistry research, Vol. 50 N° 16 (Août 2011) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 50 N° 16 (Août 2011) . - pp. 9799-9809 Titre : Monitoring the ozonation of phenol solutions at constant pH by different methods Type de document : texte imprimé Auteurs : Edgardo M. Contreras, Auteur ; Nora C. Bertola, Auteur ; Noemi E. Zaritzky, Auteur Année de publication : 2011 Article en page(s) : pp. 9799-9809 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : pH  Ozonization  Surveillance Résumé : In this study the oxidation―reduction potential (ORP) and the proton production (Hp) profiles as a function of time were proposed as indicators to monitor the ozonation of phenol solutions at constant pH. Analysis of the ozone gas outlet stream (XO3), COD, and phenol measurements in the aqueous phase confirm the reliability of the proposed indicators. Results show that the derivative with respect to time of the normalized ozone gas outlet concentration ((1/XO30)dXO3/dt), of the oxidation―reduction potential (dORP/dt) or of its logarithmic value (dLog(ORP)/dt), and of the proton production rate (dHp/dt) exhibited maximum values that were close to the critical ozonation time (tc) determined by XO3, COD, and phenol measurements. Additionally, ORP and XO3 measurements were useful to determine tc for all the tested pHs (5 to 11); however, Hp was useful only for pH values higher than 9. The indicators of the ozonation process proposed in the present work (ORP, Hp) as alternatives of XO3 may be useful to control the addition of ozone, minimizing the ozonation process costs. Note de contenu : http://acatalogue_2.biblio.intranet.enp.edu.dz/catalog.php?categ=serials&sub=analysis&action=analysis_form&bul_id=15578&analysis_id=0 DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=24425226 [article] Monitoring the ozonation of phenol solutions at constant pH by different methods [texte imprimé] / Edgardo M. Contreras, Auteur ; Nora C. Bertola, Auteur ; Noemi E. Zaritzky, Auteur . - 2011 . - pp. 9799-9809. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 50 N° 16 (Août 2011) . - pp. 9799-9809 Mots-clés : pH  Ozonization  Surveillance Résumé : In this study the oxidation―reduction potential (ORP) and the proton production (Hp) profiles as a function of time were proposed as indicators to monitor the ozonation of phenol solutions at constant pH. Analysis of the ozone gas outlet stream (XO3), COD, and phenol measurements in the aqueous phase confirm the reliability of the proposed indicators. Results show that the derivative with respect to time of the normalized ozone gas outlet concentration ((1/XO30)dXO3/dt), of the oxidation―reduction potential (dORP/dt) or of its logarithmic value (dLog(ORP)/dt), and of the proton production rate (dHp/dt) exhibited maximum values that were close to the critical ozonation time (tc) determined by XO3, COD, and phenol measurements. Additionally, ORP and XO3 measurements were useful to determine tc for all the tested pHs (5 to 11); however, Hp was useful only for pH values higher than 9. The indicators of the ozonation process proposed in the present work (ORP, Hp) as alternatives of XO3 may be useful to control the addition of ozone, minimizing the ozonation process costs. Note de contenu : http://acatalogue_2.biblio.intranet.enp.edu.dz/catalog.php?categ=serials&sub=analysis&action=analysis_form&bul_id=15578&analysis_id=0 DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=24425226

Stoichiometry of sulfite oxidation by oxygen during the determination of the volumetric mass transfer coefficient / Edgardo M. Contreras in Industrial & engineering chemistry research, Vol. 47 N° 23 (Décembre 2008) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 47 N° 23 (Décembre 2008) . - p. 9709–9714 Titre : Stoichiometry of sulfite oxidation by oxygen during the determination of the volumetric mass transfer coefficient Type de document : texte imprimé Auteurs : Edgardo M. Contreras, Auteur Année de publication : 2009 Article en page(s) : p. 9709–9714 Note générale : Chemistry engineering Langues : Anglais (eng) Mots-clés : Stoichiometry  Oxidation  Oxygen Résumé : The aim of this work was to study the effect of the initial sulfite concentration on the stoichiometric coefficient of sulfite oxidation. A combined method based on the oxidation of sulfite by oxygen in the presence of cobalt(II) (0.5 mM) as catalyst was used to determine the volumetric mass transfer coefficient (kLa) and the oxygen consumption (OC) due to sulfite oxidation. Results demonstrated that the dissolved oxygen (DO) probe response constant (ksensor) was not dependent on the DO concentration or the agitation speed; obtained ksensor values were high enough to not interfere with DO or OC measurements. Using the reaction time to sulfite depletion method, volumetric mass transfer coefficient (kLa) yielded a linear increase as a function of the initial sulfite concentration. On the contrary, from the saturation phase of DO curves, an almost constant kLa value was obtained in accordance to constant air flow rate and agitation conditions that were used in the experiments. The observed stoichiometric coefficient (OC/S0) at high initial sulfite concentrations or low kLa values was lower than the theoretical one, suggesting that the formation of elemental sulfur becomes significant at these conditions. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801079e [article] Stoichiometry of sulfite oxidation by oxygen during the determination of the volumetric mass transfer coefficient [texte imprimé] / Edgardo M. Contreras, Auteur . - 2009 . - p. 9709–9714. Chemistry engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 47 N° 23 (Décembre 2008) . - p. 9709–9714 Mots-clés : Stoichiometry  Oxidation  Oxygen Résumé : The aim of this work was to study the effect of the initial sulfite concentration on the stoichiometric coefficient of sulfite oxidation. A combined method based on the oxidation of sulfite by oxygen in the presence of cobalt(II) (0.5 mM) as catalyst was used to determine the volumetric mass transfer coefficient (kLa) and the oxygen consumption (OC) due to sulfite oxidation. Results demonstrated that the dissolved oxygen (DO) probe response constant (ksensor) was not dependent on the DO concentration or the agitation speed; obtained ksensor values were high enough to not interfere with DO or OC measurements. Using the reaction time to sulfite depletion method, volumetric mass transfer coefficient (kLa) yielded a linear increase as a function of the initial sulfite concentration. On the contrary, from the saturation phase of DO curves, an almost constant kLa value was obtained in accordance to constant air flow rate and agitation conditions that were used in the experiments. The observed stoichiometric coefficient (OC/S0) at high initial sulfite concentrations or low kLa values was lower than the theoretical one, suggesting that the formation of elemental sulfur becomes significant at these conditions. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801079e