Sulphate radical enhanced photoelectrochemical degradation of sulfamethoxazole on a fluorine doped tin oxide - copper(I) oxide photoanode

Abstract

• Visible light active FTO-Cu 2 O photoanode was successfully synthesised. • Sulphate radical was produced from persulphate salt at the surface of the Cu 2 O. • Degradation of sulfamethoxazole was markedly enhanced by sulphate radicals. • Mechanism of radicals generation and sulfamethoxazole degradation were proposed. • Application in real wastewater matrix was carried out with TOC removal of 43%. We report a sulphate radical enhanced photoelectrochemical degradation of sulfamethoxazole on a solar light driven fluorine doped tin oxide - copper(I) oxide photoanode. Copper(I) oxide was prepared by a template-free method and dispersed onto the surface of a fluorine doped tin oxide glass to form the photoanode. UV–Vis diffuse reflectance spectroscopy showed that the photoanode absorbed in the visible light region. With sodium persulphate as the source of sulphate radical, photoelectrochemical degradation studies showed that sodium persulphate markedly enhanced the degradation of sulfamethoxazole. Studies on the effects of change in concentration of the persulphate and the absence of the persulphate on the photoelectrocatalytic degradation process were conducted. Overall, the extent of degradation and mineralisation of sulfamethoxazole in water was found to be 86% and 67% respectively with bias potential of 1.5 V for the sulphate radical enhanced process. Scavenger studies showed that the photogenerated holes and sulphate radicals were the primary active species in the abatement of sulfamethoxazole. The effectiveness of sulfamethoxazole removal in real matrices by the use of FTO-Cu 2 O photoanode and sulphate radical was also confirmed.