Understanding the self-catalyzed decomplexation mechanism of Cu-EDTA in Ti3C2Tx MXene/peroxymonosulfate process

Self-catalyzed decomplexation of Cu-ethylene diamine tetraacetic acid complex (Cu-EDTA) and recovery of Cu without addition of extraneous transition metals were achieved in Ti 3 C 2 T x MXene/peroxymonosulfate (Ti 3 C 2 T x /PMS) process. Free radical quenching experiments and electron spin resonance (ESR) measurements demonstrated that both hydroxyl radical (HO • ) and sulfate radical (SO 4 •- ) contributed to the degradation of Cu-EDTA. Activation of PMS by Ti 3 C 2 T x initiated Cu-EDTA decomplexation and released free Cu ions . Then, the formation of Ti-O-Cu bonds between Cu ions and Ti 3 C 2 T x accelerated the electron transfer from Ti 3 C 2 T x to Cu(Ⅱ) and triggered Cu(Ⅱ)/Cu(Ⅰ) cycle, which further enhanced PMS activation and led to the self-catalyzed decomplexation of Cu-EDTA. Simultaneous recovery of Cu was achieved due to the excellent absorption performance of negative charged Ti 3 C 2 T x towards Cu ions. This study revealed the self-catalyzed decomplexation mechanism of Cu-EDTA in the Ti 3 C 2 T x /PMS process and provided a feasible strategy for heavy metal complexes treatment.