Novel technique to regenerate activated alumina bed saturated by fluoride ions

Abstract

A novel technique to regenerate adsorbent column is presented. The process used is based on the utilization of an electrochemical cell which regenerates several saturated adsorbent bed. This paper presents the regeneration of the activated alumina (AA) bed saturated by fluoride ions. The results obtained in this study demonstrated that desorption of fluoride from activated alumina is a rapid process. Most of the fluoride content desorbed within 6–15 min. The utilization of the electrochemical cell allows a complete desorption of the fluoride under optimum conditions. The reduction of about 90% of the sodium hydroxide amount was attained by the electrochemical process. A study of adsorption–regeneration cycles showed that the electrochemical technique was more efficient than current techniques. A 95%, recovery of the adsorption capacity was realized with the electroregeneration system. In addition, the volume of water used to regenerate the saturated bed was lower than for current regeneration techniques. The washing did not exceed 6% of the treated water volume. The electrodesorption operation was successfully applied for fluoride desorption from saturated activated alumina column by natural water with strong mineralisation. © 2001 Elsevier Science B.V. All rights reserved.