Ozonation of dimethyl phthalate catalyzed by highly active CuO-FeO nanoparticles prepared with zero-valent iron as the innovative precursor.

Heterogeneous catalytic ozonation provides a promising alternative in the degradation of recalcitrant contaminants. CuO-FeO nanoparticles (CuFeO NPs, both Cu(I) and Cu(II) were contained, about 70 nm) were creatively synthesized using Fe(0) as the precursor and subsequently employed as the ozonation catalyst for dimethyl phthalate (DMP) degradation. Results showed that DMP degradation by O/CuFeO was significantly faster than those ozonation catalyzed by CuO, FeO, or mixture of CuO and FeO (1:1 M ratio), which was ascribed to the unique CuFeO NPs that composed of abundant structural Cu(I) (≡Cu(I)). It was among the first revealing the synergistic effect between ≡Cu(I) and surface lattice oxygen (O) in HO· generation, resulting in rapid DMP degradation kinetics and high mineralization efficiency. Besides the generation of ≡Cu(I), galvanic corrosion between Fe(0) and Cu(II) also generated structural Fe(II), which could reduce the ≡Cu(II) back to ≡Cu(I), thus compensating the electron loss of ≡Cu(I) and finally obtaining a high-efficiency cycling between ≡Cu(II) and ≡Cu(I). The DMP degradation pathway was introduced based on the intermediates detected. By regulating the (re)-generation of low-valent metal (≡Cu(I)), this study provides an innovative strategy to significantly promote the generation of HO· in catalytic ozonation, which might be promising for advanced wastewater treatment.