Degradation of benzotriazole by a novel Fenton-like reaction with mesoporous Cu/MnO2: Combination of adsorption and catalysis oxidation

Abstract

Degradation of benzotriazole (BZA) as an emerging contaminant by a novel Fenton-like reaction was investigated using a catalyst prepared by incorporating Cu into mesoporous MnO2 (mesoporous Cu/MnO2, MCM). Catalysts were synthesized with different Cu contents, and were characterized by N2 adsorption–desorption, X-ray photoelectron spectroscopy, ultraviolet–visible (UV–vis) diffuse reflectance spectroscopy, and temperature-programmed reduction (TPR)-H2. The MCM functioned via surface chemisorption and redox reaction that was confirmed by intermediates identification, XPS and TPR analysis, followed by a Fenton-like oxidation derived by surface Cu+ and Mn3+, to provide high degradation efficiency for BZA in solution. Fourier transform infrared (FT-IR) spectroscopy result also verified the surface adsorption and Fenton-like reaction. MCM exhibited much higher adsorption and catalytic activity in the Fenton reaction than pure MnO2 or CuO. The effect of Cu content in MCM, catalyst dose, H2O2 dose, and solution pH were investigated. BZA degradation was high in deionized water (removal efficiency=89%) and moderate in wastewater treatment plant effluent (removal efficiency=56%) after 60-min reaction at an initial pH of 7.13, which could be developed by adjusting the dose of catalyst or H2O2. A possible mechanism for the reaction is proposed. This involves surface adsorption with copper and a redox reaction with Mn3+, followed by a copper–manganese cycle-derived Fenton-like reaction.