Ultra-efficient peroxymonosulfate utilization and trichloroethylene degradation in heterogeneous catalytic system guided by sheet-like Cu2MnO4 nanoparticles: The role of Cu(III)-O species and free radicals.

ABSTRACT

Synthesizing cubic spinel Cu2MnO4 with nanosheet structure (SCMO) aimed to construct a "non-radical-mediated radical-oxidative reaction", for increasing PMS utilization efficiency, and solving the defects of SO4•- and •OH through indirect PMS activation by electron transfer process. Compared with box-like Cu2MnO4 (11.1%, 0.0035 min-1) and ordinary Cu2MnO4 nanoparticles (21.3%, 0.0070 min-1), SCMO/PMS showed excellent trichloroethylene removal (98.8%, 0.1577 min-1). The pivotal role of Cu(III) was determined based on EPR analysis, quenching experiments, chemical probe experiments, hydrogen temperature-programmed reduction and Raman spectroscopy analysis, in-situ FTIR and Raman analyses. In brief, the interaction between PMS and SCMO could produce surface-bonded reactive complexes and the subsequent breaking of O-O bond in the sub-stable structure allowed the conversion of Cu(II) to Cu(III), which in turn facilitates the generation of •OH and SO4•-. The density functional theory (DFT) calculations provided supporting evidence for the electron donor role of SCMO and the increase of the electron acceptance capacity of PMS. SCMO/PMS system showed good resistance and degradation efficiency to complex composition and combined pollutants in actually contaminated groundwater, respectively. However, the coexistence of high concentrations of arsenic could significantly affect SCMO performance due to their adsorption on -OH groups, which still need in-depth study.