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

Abstract

• A series of copper-based bimetallic oxides are synthesized. • Cu-Al 2 O 3 exhibits excellent Fenton-like catalytic activity and stability. • Selective H 2 O 2 conversion to OH · radicals is obviously enhanced. • The possible Fenton-like reaction mechanism is discussed. 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 CuAlO 2 /Al 2 O 3 (named Cu-Al 2 O 3 ) with a sponge-like structure. Nitrogen sorption isotherm showed that the Cu-Al 2 O 3 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-Al 2 O 3 catalyst and 12.5 mM H 2 O 2 . 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-Al 2 O 3 catalyst can not only improve the reduction of Cu 2+ to Cu + but also inhibit the oxidization of H 2 O 2 to generate O 2 - · radicals via the σ - C u l i g a n d c o m p l e x associated mechanism. Overall, this study indicates that Cu-Al 2 O 3 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.