Synthetic Cu(III) from copper plating wastewater for onsite decomplexation of Cu(II)- and Ni(II)-organic complexes

Abstract

Herein, the Cu(III) synthesized from copper plating effluent was developed for the first time to evaluate the onsite degradation performance of heavy metal complexes in the wastewater, thus achieving the purpose of “treating waste with waste”. The results indicated that synthetic Cu(III) presented the excellent decomplexation performance for Cu(II)/Ni(II)-organic complexes. The removal efficiency of Cu(II)/Ni(II)-EDTA significantly increased with increasing Cu(III) dosage, and the degradation of Cu(II)/Ni(II)-EDTA by synthetic Cu(III) system displayed highly pH-dependent reactivity. The radical quencher experiments confirmed that Cu(III) direct oxidation were mainly involved in the degradation of Cu(II)-EDTA. Additionally, the continuous decarboxylation process was proven to be the main degradation pathway of Cu(II)-EDTA in Cu(III) system. The coexisting substances (SO₄²⁻, Cl⁻ and fulvic acids) showed little impacts at low level for the removal of Cu(II)/Ni(II)-EDTA, while retarded the degradation of Cu(II)-EDTA slightly at high level, which features high selective oxidation. Encouragingly, it was also effective to remove Cu(II)/Ni(II)-EDTA from in treating actual Cu/Ni-containing wastewater through synthetic Cu(III) treatment.