Mercury(II) removal from water by electrocoagulation using aluminium and iron electrodes

In this work, electrocoagulation was used to evaluate the treatment of synthetic solutions containing mercury(II) of concentration 2 x 10(-5) M. The effects of the distance between the electrodes, current density, charge loading and initial pH on the removal efficiency were investigated, using aluminium and iron electrodes. Analysis of the filtrates resulting from the treatment was made by anodic redissolution in the differential pulse mode. The removal efficiency was above 99.9% when the distance between the electrodes was 3 cm, the current density ranging from 2.5 to 3.125 A dm(-2); for instance, 99.95% of the mercury(II) was eliminated when a charge loading of 9.33 and 15.55 F m(-3) were used for iron and aluminium respectively. In these conditions, by varying the pH of the mercury(II) solutions from 3 to 7, the removal efficiency remained higher than 99%. In addition, some experiments were carried out on a river water contaminated with mercury(II) ions, and the results obtained showed that the presence of organic matter do not influence the efficiency of the treatment. The elimination of mercury(H) ions is best performed with iron, where 15 min of electrolysis was sufficient to reach the highest removal compared to aluminium which required 25 min for the same result. (C) 2009 Elsevier B.V. All rights reserved.