Migration and transformation of Cu(II)-EDTA during electrodialysis accompanied by an electrochemical process with different compartment designs

Abstract Further research into more cost-effective methods to treat toxic metal-ethylenediaminetetraacetate (Me-EDTA) complexes is required due to their high bioavailability. In this study, we compared electrodialysis (ED) with different compartment designs (2-, 3- and 4-compartment designs) and electrochemical oxidation (EO, 1-compartment design) to treat a dilute Cu(II)-EDTA solution (1 mM). After a 48-h treatment with a constant current applied at 32 mA, the Cu removal efficiencies were achieved at 49%, 87%, 79% and 96% for 1-compartment EO and 2- to 4-compartment ED, respectively, and the total organic carbon concentrations decreased from 138 mg/L to 100, 64, 57 and 39 mg/L, respectively. The energy consumptions for 1-compartment EO and 2- to 4-compartment ED were 7.7, 8.4, 13.9 and 15.4 W h, respectively. Based on all above results, the most cost-effective design was determined to be the 2-compartment ED. Moreover, the 3- and 4-compartment ED treatments have faster contaminant removal kinetics than 1-compartment EO and 2-compartment ED. This study clarified the mechanisms of the migration and the transformation of Cu-EDTA during EO and ED with different membrane combinations, which is helpful for improved selection of compartment design for metal-chelate complex removal.