Research on heavy metal recovery using the electrokinetic phenomenon

Recently, pollution of the soil by heavy metal elution from industrial effluents and so on has become a serious problem. Until now, many techniques such as diffusion prevention and elution prevention, extraction and removal, decomposition and decontamination have been proposed with regard to processing of polluted soil. Of particular note is the method using the electrokinetic phenomenon. In this method, the paired electrode is inserted in the soil, and DC voltage is applied. Then, the electrokinetic phenomenon by the procedure of the superscription, namely, electrophoresis, electroendosmosis, electrolysis, is utilized. However, in conventional research, the recovery quantity of heavy metal ions is low, and improvement of the recovery efficiency is desired in order to utilize this technique for the repair of polluted soil. The reason why the recovery efficiency of heavy metal ions decreases is as follows. When the heavy metal ion has moved from the anode to the cathode, it combines with hydroxide ion produced by electrolysis of the water at the cathode, and it has precipitated as a hydroxide. The purpose of this study is to prevent alkalinization by adding acid in the proper quantity, so as to improve the efficiency of heavy metal ion recovery. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 158(1): 1–7, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20312