Removal of benzohydroxamic acid-metal complexes pollution from beneficiation wastewater by metal-biochar/peroxymonosulfate system: Behaviors investigation and mechanism exploration

The organometal complexes pollution in beneficiation wastewater has aroused increasing attentions because they were difficult to remove by traditional technologies. In this study, eleven kind of benzohydroxamic acid (BHA)-metal (Pb2+, Cu2+, Mg2+, Ca2+, Zn2+, Cd2+, Fe3+, Fe2+, Sb3+, Cr(Ⅵ) and As(V)) complexes were chosen to investigate their removal performance and mechanism in heterogeneous persulphate degradation system. The metal-biochar/peroxymonosulfate (PMS) system showed the highest and worst total organic carbon (TOC) removal efficiency for BHA-Fe2+ (68.4%) and BHA-As(V) (22.8%), respectively. Meanwhile, the metal-biochar composite had different immobilization abilities toward multiple metal ions. Density functional theory (DFT) revealed that ΔG values of various BHA-metal complexes played key roles for TOC removal. While, metal adsorption was mainly depended on the functional groups on the catalyst surface. After the reaction, Cu, Pb, Fe, Sb, Cr and As mainly existed as residuals. Overall, this study has provided valuable and novel insights into the removal of BHA-metal complexes and broadened the practical applicability of the waste solid-based metal-biochar catalyst coupled with persulphate in beneficiation wastewater treatment.