Trace copper doped LaMnO3 perovskite for PMS activation via electron transfer process towards pollutant elimination

Abstract

Doping strategies are widely employed to enhance the catalytic activity of perovskites for peroxymonosulfate (PMS) activation in removing organic pollutants in water. However, limited research has explored the performance enhancement and underlying mechanism associated with trace doping, which is particularly important for saving dopant metals and cost, and also lower the risk of metal ion loss. In this study, we investigated the profound effects of trace copper doping in LaMnO₃ on PMS activation for contaminant removal. Compared to pristine LaMnO₃, the catalytic oxidation performance was significantly enhanced by trace copper doping (1.3 wt% Cu), achieving over 91.0 % removal of acid orange 7 (AO7) within 45 min using the LaMn_0.95Cu_0.05O₃ (LMC5)/PMS system. Comprehensive characterizations revealed that copper incorporation primarily fortified the redox ability and electron transfer efficiency of LaMnO₃, thereby improving its catalytic efficacy. Furthermore, unlike previous studies reporting on radical oxidation mechanisms, the surface PMS* complexes with Mn(III) serving as the active sites were identified as the predominant reactive species responsible for pollutant degradation. The intermediates of pollutant degradation were identified and their toxicity was also assessed by ECOSAR program. The system's practical feasibility was further underscored by treating diverse contaminants and evaluating the interference of coexisting anions in water. Briefly, this study provides valuable insights into enhancing the catalytic activity of perovskites for PMS activation in water treatment.