Acetic acid-assisted fabrication of hierarchical flower-like Bi2O3 for photocatalytic degradation of sulfamethoxazole and rhodamine B under solar irradiation

With the assistance of acetic acid (CH3COOH), a novel 3D flower-like Bi2O3 was synthesized via hydrothermal process followed by calcination. For the first time, the role of CH3COOH as a capping agent in the formation of flower-like structure was investigated. The as-prepared flower-like Bi2O3 had a high activity on the degradation of sulfamethoxazole (SMX) under simulated solar light irradiation due to the narrow band gap of 2.69 eV, high percentage of beta-Bi2O3 as well as high intensity of polar facets (1 2 0) and (2 00). Meanwhile, the photocatalytic degradation followed apparent pseudo-first-order kinetics. The rate constant (k) increased from 0.7 x 10(-2) to 3.0 x 10(-2) min(-1) with the catalyst loading varying from 0.5 to 2.0 g L-1. Increasing pH values from 3 to 11 led to the decrease of k from 2.2 x 10(-2) to 0.2 x 10(-2) min(-1), which could be attributed to the electrostatic adsorption between SMX molecules and Bi2O3. The radical quenching experiments showed both direct (h(+)) and indirect oxidation (.OH and .O-2(-])) happened in this process. (C) 2017 Published by Elsevier Inc.