Easily Regenerated CuO/γ-AlO for Persulfate-Based Catalytic Oxidation: Insights into the Deactivation and Regeneration Mechanism.

In this work, γ-AlO-supported CuO (-CuO/AlO) materials are successfully synthesized using a novel impregnation-precipitation-decomposition method. The obtained -CuO/AlO catalyst shows excellent catalytic activities for bisphenol A (BPA) degradation with sodium persulfate (PDS) as an oxidant. Radical quenching tests and electron paramagnetic resonance (EPR) studies indicate that PDS activation is a combined mechanism involving both free radical and nonfree radical pathways. In a continuous large-scale degradation process, about 1.78 L of 20 ppm BPA can be completely removed within 480 min. Although -CuO/AlO can be deactivated after several reaction cycles, the catalytic activity can be regenerated after simple aerobic calcination. X-ray photoelectron spectroscopy (XPS) and Raman analysis confirm that the deactivation of -CuO/AlO should be attributed to the conversion of Cu(II) to Cu(I). The aerobic calcination could oxidize Cu(I) back to Cu(II), thus recovering the catalytic activity. In addition, the density functional technology (DFT) and temperature-programmed oxidation (TPD) results reveal that γ-AlO can not only serve as a carrier to anchor the CuO particles but also can adsorb and activate PDS by introducing more basic sites on the surface. -CuO/AlO has high activity and can be regenerated easily, thus having great potential applications for wastewater treatment.