Facile synthesis of copper-based bimetallic oxides for efficient removal of bisphenol a via Fenton-like degradation

In this study, three copper-based bimetallic oxides (Cu-M, M: Al, Fe, and Zn) were prepared via a facile hydrothermal method and used as the catalyst for the Fenton-like process to degrade bisphenol A (BPA). Compared to other bimetallic oxides, Cu-Al bimetallic oxide exhibited excellent catalytic activity. The results of XRD, TEM, SEM, and EDS illustrated that Cu-Al was synthesized as CuAlO2/Al2O3 (named Cu-Al2O3) with a sponge-like structure. Nitrogen sorption isotherm showed that the Cu-Al2O3 was consists of mesoporous with a high specific surface area and a narrow pore size distribution. FTIR spectra indicated the formation of a Cu - ligand complex between BPA and the surface Cu of the catalyst. 90% of BPA could be degraded within 90 min when adding 0.75 g/L (Cu-7.8 wt%) Cu-Al2O3 catalyst and 12.5 mM H2O2. Furthermore, it still kept over 70% removal efficiency after ten consecutive cycles, suggesting the superior stability of the catalyst. Based on the XPS and radical quenching experiments results, the Cu-Al2O3 catalyst can not only improve the reduction of Cu2+ to Cu+ but also inhibit the oxidization of H2O2 to generate O-2(-)center dot radicals via the sigma-Cu ligand complex associated mechanism. Overall, this study indicates that Cu-Al2O3 is a promising catalyst for the Fenton-like process. In addition, the strategy of the construction of the electron-rich catalytic site is an effective method to address the drawbacks of the classical Fenton process.