Effects of Complexes and pH Buffer Solution in Electrokinetic Oxidation Treatment on Sediments Chromium Removal

Abstract

Three electrokinetic (EK) experiments were designed to study the remediation efficiency of Cr(III) by EK-oxidation method and to investigate the influence of complexes and pH buffer solution in EK-oxidation process. Sediments Cr (III) can be oxidized into Cr(VI) effectively by KMnO4, but the oxidation efficiency is not proportional to the dose of oxidant, and chemical oxidation process leads to a bit lower buffering capacity of the sediment. Compared with the simple EK remediation, the removal efficiency of total Cr in the sediments increased 32.6% by EK-oxidation method, and the concentrations of total chromium in the sediment showed increasing trend from the cathode to the anode after EK-oxidation treatment. The pH control and KMnO4 improved the removal of Cr(VI) and total Cr from the sediments. Due to stronger complexation action of citric acid with Cr(III) in sediments, citric acid in the catholyte obviously increased the removal rate of total Cr in sediments. Finally, the removal rate of total Cr from sediments reached 60.9% by adding complex and controlling the pH of cathode and anode pond solution on EK-oxidation processes.