M. Drouiche

Fluoride removal with electro-activated alumina

“Ecole Nationale Polytechnique dillger, B.P. 182-16200, El Harrach, Alger, Algeria “DPpartement GEnie chimique, University of Technology of Compiggne, B.P. 20.509, 60205 CompiGgne cedex, France Tel. +33 (3) 44 23 44 57; Fox: +33 (3) 44 23 52 16; email: nabil.mameri@utc.j? Received 15 November 2002; accepted 10 February 2003 Abstract A new activation technique using alumina was developed for the removal of fluoride from water. This technique is based on an electro-activation by means of an electrical field. The optimum activation parameters (potential and contact time) were determined, and an activation time of about 120 min and a potential of +lOO mV/SCE were then selected. The effect of various experimental parameters - ionic strength, pH hardness, and fluoride-alumina concentration ratio GGb- was determined for the adsorption capacities ofthe electro-activated alumina. The effect ofthese parameters on the fluoride adsorption capacities of both electro-activated adsorbent and conventional alumina was essentially the same, except for the ionic strength parameter. Indeed, ionic strength did not have a considerable effect on the performance of the conventional alumina. However, for the electro-activated alumina, an increase in ionic strength induced a slight increase in the fluoride adsorption capacity ofthe electro-activated adsorbent. The optimum conditions, determined in the batch mode, gave an optimal pH ranging from 3.5 to 5 and a C,,/C, ratio of about 4. At a NaCl concentration of 800 mg dm3, the fluoride adsorption capacity of the electro-activated alumina was about 55% better than that of conventional alumina. Keywordrs: Adsorbent activation; Electrochemical technique; Fluorine; Alumina