Electrochemical generation of aluminum sorbent for fluoride adsorption

Aluminum sorbent (Al-sorbent) was produced in a parallel-plate electrochemical reactor by anodic dissolution of aluminum electrodes in a dilute sodium chloride (NaCl) aqueous solution. The NaCl in the solution effectively reduced the power consumption and promoted the sorbent generation by depasivating the aluminum-water electrochemical system. The freshly generated Al-sorbent was able to reduce fluoride concentration from 16 to 2 mg/l in 2 min. The final concentration was further reduced to 0.1 mg/l by partial neutralization of the mixture to pH 6.3. The sorbent generation and fluoride adsorption was integrated into a single electrochemical reactor. The system was able to reduce the fluoride concentration from 16 to 6 mg/l in 2 min of treatment and to about 2 mg/l in 4 min. The effluent from the electrochemical system needs pH adjustment to bring the fluoride concentration down to less than 1 mg/l. (C) 2002 Elsevier Science B.V. All rights reserved.