Enhanced washing of cadmium and lead from polluted river sediment using horizontal electroosmosis

Sediments are an important sink for heavy metals in river and lake waters, and their chemical compositions affects the circulation of these elements in the ecosystem. Therefore, the remediation of polluted sediments is critical for the health of the ecological environment. This work proposes a facile method for the enhancement of heavy metals extraction from contaminated sediment. In this work, horizontal electroosmosis was applied to improve extraction efficiency of Cd and Pb from river sediment. The effect of the washing reagent (distilled water, citric acid, nitric acid, acetic acid and EDTA) on remediation was investigated, and optimization of the operational parameters of remediation time, washing reagent concentration, electrode spacing, and applied voltage were also studied. Citric acid and EDTA were found to give rise to the greatest removal ratio for Cd and Pb, respectively, with electroosmosis enhancement. After electrokinetic washing for 13 days at cell voltage of 30 V, the removal ratio of Cd by citric acid was 77.0%, and that of Pb by EDTA was 88.3%, at the initial concen-trations of 30.2 and 304.2 mg kg (dry solids), respectively. Decreases in exchangeable, carbonate-bound and iron-manganese oxide-bound fractions of the heavy metals were apparent upon their removal from the polluted river sediment.