Photocatalytic degradation of acetaminophen over Ag, Au and Pt loaded TiO2 using solar light

Abstract

The sustainability and feasibility of using solar irradiation instead of UV light in photocatalysis is a promising approach for water remediation. In this study, photocatalytic degradation (PCD) of a widely used analgesic and antipyretic drug, acetaminophen (AP), with noble metal loaded TiO2 photocatalysts (Ag/TiO2, Au/TiO2 and Pt/TiO2) was investigated in aqueous suspension using solar light. The deposition of noble metals (Ag, Au and Pt) onto the TiO2 surface enhanced the PCD of AP under different operating conditions including pH, surfactants and drug excipients. However, lower degradation rate constants of AP were obtained under simulated and direct solar light as compared to UV light. The degradation mechanism of AP under UV as well as simulated solar light was found to follow similar, though not identical, reaction pathways leading to hydroxylated intermediates (e.g. 4-acetamidoresorcinol (4-AR), 4-acetamidocatechol (4-AC) and hydroquinone (HQ)) through competitive routes. The PCD of AP followed a pseudo first order kinetics according to Langmiur-Hinshelwood model. Noble metal (Ag, Au and Pt) loaded TiO2 photocatalysts can be used effectively to degrade AP in water under both solar and UV light.