Activation and stabilization of the Cu species via strong CuO-CeO2 interactions for enhanced decomposition of refractory aromatic organic pollutants in water

Abstract

The copper (Cu)-driven advanced oxidation process (AOP) represents one green and efficient technology for the removal of refractory aromatic organic pollutants from water. However, its application remained challenged by the sluggish regeneration of the active Cu+ species and the environmental risk induced by Cu leaching. Herein we reported a facile approach to the bimetallic composite CuCeOx-A catalyst with strong CuO-CeO2 interactions (“A” referred to the acid-activation process). It enabled a TOC removal efficiency (δ%) of 92.4 % and a turnover frequency (TOF) of 1.57 min−1 for TOC removal from 100 mg/L 2-naphthol aqueous solution, outperforming the CuO (δ% = 82.9 % and TOF = 0.23 min−1) and most of the reported Cu-based catalysts. It was more active under neutral/weakly acidic conditions, and could keep high performances in a wide 2-NAP concentration window and in the presence of some impurity ions (PO43-, NH4+ or SiO32-). Additionally, the Cu leaching of CuCeOx-A maintained at a much lower level of ∼ 1.0 ± 0.2 mg/L than that of CuO (∼12.8 ± 1.9 mg/L). Mechanistic studies demonstrated that the enhanced AOP performance and chemical stability of CuCeOx-A originated from the strong CuO-CeO2 interactions, which facilitated the Cu+ regeneration by up-lifting the redox potential of Cu2+/Cu+ and stabilized Cu species via the Cu–O-Ce bonds. Further biological safety testing using chlorella cells as probe organism revealed that the CuCeOx-A-driven AOP was environmentally benign for aromatic organic pollutants removal.