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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

Photo-fenton treatment of actual agro-industrial wastewaters / Bedoui Ahmed in Industrial & engineering chemistry research, Vol. 50 N° 11 (Juin 2011) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 50 N° 11 (Juin 2011) . - pp 6673–6680 Titre : Photo-fenton treatment of actual agro-industrial wastewaters Type de document : texte imprimé Auteurs : Bedoui Ahmed, Auteur ; Elalaoui Limem, Auteur ; Ahmed Abdel-Wahab, Auteur Année de publication : 2011 Article en page(s) : pp 6673–6680 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Agro-industrial  wastewaters  Photo-Fenton  process Résumé : In this work, the treatment of actual agro-industrial wastewaters by photo-Fenton process was investigated. The actual agro-industrial wastewaters (AIW) were received from physicochemical treatment plants of wastewaters coming from the olive oil milling industry. These brown colored aqueous wastes have been characterized by high organic content with chemical oxygen demand (COD) in the range 2000–7000 mg O2 L–1, which makes difficult the degradation of these wastewaters by traditional biological methods. The photo-Fenton process was successfully used to totally decolorize these effluents and to satisfactory remove aromaticity and COD contained in these wastes. The influence of some experimental parameters such as H2O2 and Fe2+ doses, initial COD content, initial pH, and temperature on color, aromaticity, and COD removals has been studied to find out the optimum conditions leading to maximum efficiency of the photo-Fenton process. The best results of photo-Fenton process treatment of AIW (2000 mg O2 L–1) have been obtained using 3 g L–1 H2O2 and 30 mg L–1 Fe2+ at pH 3 and T = 26 °C and after 3 h UV irradiation. The comparison among photo-Fenton, Fenton, and UV/H2O2 processes has shown that the photo-Fenton process is more efficient and cost-effective than the two other processes. During the photo-Fenton process, photodecomposition and catalytic by Fe2+ ions decomposition of H2O2 leads to the production of higher amounts of hydroxyl radicals, proving that the efficiency of an advanced process is generally related to the amount of hydroxyl radicals produced during the treatment. The degradation of organics contained in the actual agro-industrial wastes during photo-Fenton treatment involves many successive oxidation/reduction reactions, including a rapid release of chromophores leading to the total decolorization, then an oxidative opening of benzene rings into aliphatic intermediates without carbon dioxide formation, and finally a slower oxidation of the aliphatic intermediates by hydroxyl radicals to achieve high COD removal. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie200266d [article] Photo-fenton treatment of actual agro-industrial wastewaters [texte imprimé] / Bedoui Ahmed, Auteur ; Elalaoui Limem, Auteur ; Ahmed Abdel-Wahab, Auteur . - 2011 . - pp 6673–6680. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 50 N° 11 (Juin 2011) . - pp 6673–6680 Mots-clés : Agro-industrial  wastewaters  Photo-Fenton  process Résumé : In this work, the treatment of actual agro-industrial wastewaters by photo-Fenton process was investigated. The actual agro-industrial wastewaters (AIW) were received from physicochemical treatment plants of wastewaters coming from the olive oil milling industry. These brown colored aqueous wastes have been characterized by high organic content with chemical oxygen demand (COD) in the range 2000–7000 mg O2 L–1, which makes difficult the degradation of these wastewaters by traditional biological methods. The photo-Fenton process was successfully used to totally decolorize these effluents and to satisfactory remove aromaticity and COD contained in these wastes. The influence of some experimental parameters such as H2O2 and Fe2+ doses, initial COD content, initial pH, and temperature on color, aromaticity, and COD removals has been studied to find out the optimum conditions leading to maximum efficiency of the photo-Fenton process. The best results of photo-Fenton process treatment of AIW (2000 mg O2 L–1) have been obtained using 3 g L–1 H2O2 and 30 mg L–1 Fe2+ at pH 3 and T = 26 °C and after 3 h UV irradiation. The comparison among photo-Fenton, Fenton, and UV/H2O2 processes has shown that the photo-Fenton process is more efficient and cost-effective than the two other processes. During the photo-Fenton process, photodecomposition and catalytic by Fe2+ ions decomposition of H2O2 leads to the production of higher amounts of hydroxyl radicals, proving that the efficiency of an advanced process is generally related to the amount of hydroxyl radicals produced during the treatment. The degradation of organics contained in the actual agro-industrial wastes during photo-Fenton treatment involves many successive oxidation/reduction reactions, including a rapid release of chromophores leading to the total decolorization, then an oxidative opening of benzene rings into aliphatic intermediates without carbon dioxide formation, and finally a slower oxidation of the aliphatic intermediates by hydroxyl radicals to achieve high COD removal. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie200266d