Applicability of electrochemical technologies for removing and monitoring Pb2+ from soil and water

This work examines electrolcinetic remediation (ER) processes for removing Pb2+ in contaminated soils. For this purpose, different cathodic supporting electrolytes (NaNO3 0.1 M, EDTA 0.1 M and citric acid 0.1 M) were used into the catholyte reservoir, while in the anodic compartment, a solution of NaNO3 0.1 M was used. Additionally, the application of direct current (DC) and reverse polarity (RP) for removing of Pb2+ from the soil was also evaluated. Regarding to results obtained in this study indicated that RP and citric acid favored an efficient electromigration of Pb2+, favoring its elimination from the soil. This behavior can be explained because the elimination of Pb2+ depended on the dissolution/precipitation ionic species as well as the pH in the soil, which were maintaining in different sections in the soil, contributing to maintain the pH conditions, by using RP and citric acid, promoting the lead elimination. In order to use a feasible approach for monitoring Pb2+ concentration, adsorptive stripping voltammetry (AdSV) technique was used, obtaining acceptable confidence and good sensitivity for the concentration of Pb2+ with LOD about 0.1 mg L-1. Phytotoxicity tests showed that the ER process could be useful as a treatment technique for reducing hazardous soil toxicity polluted with Pb2+. The results confirmed the significant reduction of the germination in the anodic and cathodic regions for ER by applying DC with NaNO3 and EDTA as cathodic solutions. However, high germination (60-80%) was obtained for ER by using NaNO3 and citric acid solutions in cathodic compartments by applying RP or DC, respectively. Finally, the effluent generated by ER technology, in each one of experiments, was treated by electrocoagulation with Al electrodes, obtaining complete removal of Pb2+ from liquid after 60 min.