Rapid degradation of Omeprazole and highly effective inactivation of E. coli in the UVA-light photocatalytic process with Cu-doped in spinel-structured ɣAl2O3 as a stable catalyst

Abstract

Herein, a spinel alumina structure photocatalyst was prepared by a one-pot modified sol–gel technique with rational design and unique electronic structure evolution by Cu doping in the γAl2O3 lattice. Based on the obtained results of a full material characterization (incl. NH3-TPD, 27Al solid-state NMR, XPS, HAADF-STEM), the Cu-γAl2O3 xerogel nanomaterial displayed high dispersion of copper, significant quantities of high-density acid sites, an increase of the oxygen vacancies (OVs) on its surface, and high light absorption efficiency. This mesoporous Cu-γAl2O xerogel displayed brilliant photocatalytic performance under UVA-LED, owing to its suitable band gap, degrading around 92 % of 20 mg/L Omeprazole (OMP) in 30 min (pH = 7, catalyst = 50 mg/L). The effect of operating parameters was investigated, such as pH, concentration of Cu-ɣAl2O3/OMP, water matrix, and stability; the synthesized nanomaterial has shown outstanding stability and recyclability for four runs. The reaction mechanism was proposed using scavenging experiments, and EPR spectroscopy, Cu-doping-induced oxygen vacancies to promote charge separation and molecular oxygen activation, generating mainly ∙OH. The OMP degradation pathway was proposed (LC-MS), while the produced Cu-ɣAl2O3 nanomaterial effectively catalyzed the inactivation of >99.99 % E. coli.