Ultra-rapid and long-lasting activation of peracetic acid by Cu-Co spinel oxides for eliminating organic contamination: Role of radical and non-radical catalytic oxidation

Peracetic acid (PAA)-based advanced oxidation processes (AOPs) have attracted considerable attention in organic wastewater purification for yielding reactive oxidative species (ROS) with high performance and long lifetime. However, searching for economical and stable activators is a huge obstacle. In this work, we used a facile second transition metal embedding approach to prepare bimetallic spinel oxides (CuCo2O4) through embedding Cu to Co3O4, which was used as the activator for the rapid and durable activation of PAA to remove model organic pollutant bisphenol A (BPA). Under identical conditions, the rate constant of the constructed CuCo2O4/PAA system (0.0412 min−1) was 21.7 and 3.3 times that of CuO/PAA (0.0019 min−1) and Co3O4/PAA (0.0125 min−1) system alone, respectively. The CuCo2O4/PAA system had better resistance to co-existed ions and natural organic compounds. Meanwhile, the as-prepared materials maintained excellent stability during four-cycle tests and gradient experiments, confirming their perfect application potential. Combining the capture experiments, chemical probe, electron paramagnetic resonance, and theoretical calculations, the singlet oxygen (1O2) and organic radicals (R-O•, e.g., CH3C(O)O• and CH3C(O)OO•) were validated to be the dominant ROS. The density functional theory (DFT) calculations indicated that both BPA and PAA were more easily adsorbed onto the CuCo2O4 surface and bimetallic internal cycle opening was more likely to occur, which accelerated the PAA activation and the contaminants decomposition for rapid electron supply. This study provides new ideas for the design of alternative alloy oxides as efficient PAA activators, and further broadens the applicability of non-homogeneous PAA-based AOPs in wastewater decontamination.