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Defluoridation of Morocco drinking water by electrocoagulation/electroflottation in an electrochemical external-loop airlift reactor

Bennajah, Mounir and Gourich, Bouchaib and Essadki, Abdel Hafid and Vial, Christophe and Delmas, Henri Defluoridation of Morocco drinking water by electrocoagulation/electroflottation in an electrochemical external-loop airlift reactor. (2009) Chemical Engineering Journal, vol. 148 (n° 1). pp. 122-131. ISSN 1385-8947

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Official URL: http://dx.doi.org/10.1016/J.CEJ.2008.08.014

Abstract

An innovative application of external-loop airlift reactors as electrocoagulation/electroflotation cells with Al electrodes for defluoridation of drinking water was developed. Liquid overall recirculation and mixing were induced only by hydrogen microbubbles electrochemically generated from the cathode. This application was carried out in a 20 L external-loop air liftreactor both under semi-batch and continuous flow conditions. Results showed that liquid recirculation could be correlated to current density and gas–liquid dispersion height in the separator. Experimental data obtained at optimum conditions that favored simultaneously mixing and flotation confirmed that concentrations lower than 1.5 mg/L could be achieved when initial concentrations were between 10 and 20 mg/L. The effects of conductivity and pH agreed with the literature. Conversely, the low electrode surface vs. reactor volume ratio merged the formation of fluoroaluminum microflocs near the electrodes to fluoride adsorption on these particles in the riser and the separator sections, which differed from conventional EC cells. Consequently, defluoridation could be achieved at lower energy and electrode consumptions than in the literature. An optimum current density was defined at j = 6 mA/cm2 for pH 5, accounting simultaneously for mixing, reaction time, yield and operating costs. A promising attempt of transposition from batch to continuous process was also reported in this work, as flotation avoids the need for a downstream settling unit.

Item Type:Article
Additional Information:Thanks to Elsevier editor. The definitive version is available at http://www.sciencedirect.com The original PDF of the article can be found at : http://www.sciencedirect.com/science/article/pii/S1385894708005196
Audience (journal):International peer-reviewed journal
Uncontrolled Keywords:
Institution:French research institutions > Centre National de la Recherche Scientifique - CNRS
Université de Toulouse > Institut National Polytechnique de Toulouse - INPT
Other partners > Université Hassan II Casablanca - UH2C (MOROCCO)
Université de Toulouse > Université Paul Sabatier-Toulouse III - UPS
Other partners > Université Blaise Pascal - UBP (FRANCE)
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Deposited By:Audrey LEFEVRE

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