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Degradation and mineralization of organic pollutants contained in actual pulp and paper mill wastewaters by a UV/H2O2 process / Bedoui Ahmed in Industrial & engineering chemistry research, Vol. 48 N° 7 (Avril 2009) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 48 N° 7 (Avril 2009) . - pp. 3370–3379 Titre : Degradation and mineralization of organic pollutants contained in actual pulp and paper mill wastewaters by a UV/H2O2 process Type de document : texte imprimé Auteurs : Bedoui Ahmed, Auteur ; Mohamed Hasni, Auteur ; Elalaoui Limem, Auteur Année de publication : 2009 Article en page(s) : pp. 3370–3379 Note générale : Chemical engineering Langues : Anglais (eng) Mots-clés : UV/H2O2  treatment  Wastewaters  Chemical  oxygen  demand  Total  organic  carbon  Carboxylic  acids Résumé : In this work, UV/H2O2 treatment of actual pulp and paper mill wastewater (PPMW) was investigated. To determine optimal conditions, the effects of some experimental parameters (initial pH, initial H2O2 concentration, temperature, and organics load) on the UV/H2O2 process efficiency in terms of absorbance at 330 and 281 nm and chemical oxygen demand (COD) and total organic carbon (TOC) removals were studied. The results show that the UV/H2O2 system leads successfully to the almost-complete elimination of absorbance at 330 and 281 nm, COD, and TOC from an actual PPMW containing 270 mg of C L−1 under natural pH (pH 11.25) using 2.1 g of H2O2 L−1 at 28 °C. Under these optimal conditions, pseudo-first-order kinetics was determined for absorbance at 330 and 281 nm and COD decay with rate constants of 0.029, 0.02, and 0.008 min−1, respectively. Furthermore, the evolution with time of the H2O2 concentration exhibits two parts: a linear decrease to 300 min and then exponential change until the end of the treatment. This shows that the kinetics of H2O2 disappearance changes during the treatment from a pseudo-zeroth-order reaction in the first steps to a pseudo-first-order reaction in the final steps. On the other hand, a continuous decrease of pH and a rapid total phenols disappearance were observed during UV/H2O2 treatment of PPMW. These results suggest that several steps are involved in the photochemical oxidation of organics, starting with degradation of lignin derivatives and tannins to obtain aromatic intermediates that then undergo oxidative ring opening, leading to aliphatic carboxylic acids. In the final steps, carboxylic acids are mineralized into CO2 and H2O. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801755u [article] Degradation and mineralization of organic pollutants contained in actual pulp and paper mill wastewaters by a UV/H2O2 process [texte imprimé] / Bedoui Ahmed, Auteur ; Mohamed Hasni, Auteur ; Elalaoui Limem, Auteur . - 2009 . - pp. 3370–3379. Chemical engineering Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 48 N° 7 (Avril 2009) . - pp. 3370–3379 Mots-clés : UV/H2O2  treatment  Wastewaters  Chemical  oxygen  demand  Total  organic  carbon  Carboxylic  acids Résumé : In this work, UV/H2O2 treatment of actual pulp and paper mill wastewater (PPMW) was investigated. To determine optimal conditions, the effects of some experimental parameters (initial pH, initial H2O2 concentration, temperature, and organics load) on the UV/H2O2 process efficiency in terms of absorbance at 330 and 281 nm and chemical oxygen demand (COD) and total organic carbon (TOC) removals were studied. The results show that the UV/H2O2 system leads successfully to the almost-complete elimination of absorbance at 330 and 281 nm, COD, and TOC from an actual PPMW containing 270 mg of C L−1 under natural pH (pH 11.25) using 2.1 g of H2O2 L−1 at 28 °C. Under these optimal conditions, pseudo-first-order kinetics was determined for absorbance at 330 and 281 nm and COD decay with rate constants of 0.029, 0.02, and 0.008 min−1, respectively. Furthermore, the evolution with time of the H2O2 concentration exhibits two parts: a linear decrease to 300 min and then exponential change until the end of the treatment. This shows that the kinetics of H2O2 disappearance changes during the treatment from a pseudo-zeroth-order reaction in the first steps to a pseudo-first-order reaction in the final steps. On the other hand, a continuous decrease of pH and a rapid total phenols disappearance were observed during UV/H2O2 treatment of PPMW. These results suggest that several steps are involved in the photochemical oxidation of organics, starting with degradation of lignin derivatives and tannins to obtain aromatic intermediates that then undergo oxidative ring opening, leading to aliphatic carboxylic acids. In the final steps, carboxylic acids are mineralized into CO2 and H2O. En ligne : http://pubs.acs.org/doi/abs/10.1021/ie801755u