Electrokinetic remediation of dredged sediments polluted with heavy metals with different enhancing electrolytes

Electrokinetic removal of Cu, Zn, Cd, Cr, Pb and Ni from contaminated dredged material has been carried out on thirteen tests evaluating the effectiveness of different enhancing solutions of different nature (distilled water, citric acid, acetic acid, humic acid and EDTA). Several experimental variables were analyzed (type of enhancing solution, concentration, zeta potential, initial and final pH of the anolyte and catholyte, constants of chelation equilibriums (log beta) and precipitation (pKs), ionic mobility and charge density passed) and the main mechanisms of their action were critically analyzed. It was derived that there is not just one enhancing solution that is the best universal one for all the metals in the sediment and that modeling of the decontamination process should incorporate the particularities of the different species. However, as a generalization, it could be said that, apart from the charge density passed, the pH of the cathodic solution, quelation ability, and the zeta potential seems to appear as the most relevant factors in the efficiency of the process. (c) 2012 Elsevier Ltd. All rights reserved.