Remediation of Cu-contaminated soil using chelant and EAOP

Abstract

An electrochemical advanced oxidation process (EAOP) was used for treatment of the washing solution obtained during leaching of Cu (364 ± 2 mg kg−1) contaminated soil, with chelant S,S isomer of ethylenediamine disuccinate ([S,S]-EDDS). In the EAOP (constant current density 40 mA cm−2), a boron-doped diamond anode was used for the generation of hydroxyl radicals and oxidative decomposition of [S,S]-EDDS-metal complexes in the washing solution. The released Cu was mostly electro-deposited on the stainless-steel cathode. Three consecutive additions of 5 mmol kg−1 [S,S]-EDDS removed 46% of the Cu from the soil, mostly from carbonate and oxide soil fractions (87 and 99% Cu reduction). The soil Cu oral availability in the simulated stomach and intestinal phases (in vitro physiologically based extraction test) was reduced by 5.5 and 4.6-times. Cu plant availability (in vitro diethylenetriamine pentaacetate test) was reduced by 3.6-times. The discharge solution was clear, almost colorless, with pH 8.4, 0.45 mg L−1 Cu and 0.01 mM EDDS.