Photodegradation and mineralization of metronidazole by a novel quadripartite SnO2@TiO2/ZrTiO4/ZrO2 photocatalyst: Comprehensive photocatalyst characterization and kinetic study

Abstract

A facile hydrothermal technique was used to prepare a novel quadripartite SnO2@TiO2/ZrTiO4/ZrO2 (STZZ) photocatalyst, and the photocatalytic activity of STZZ was successfully tested in the metronidazole (MNZ) photodegradation under UV irradiation in water. The effects of photocatalyst type, pH, photocatalyst dosage, MNZ initial concentration on the photodegradation of MNZ were also evaluated. The maximum degradation of MNZ was achieved with STZZ photocatalyst at pH = 6.5 with a photocatalyst dosage of 0.07 g L−1 and MNZ concentration of 20 mg L−1. The rate constants of MNZ photodegradation and mineralization processes were 0.017 min−1 (t1/2 = 40.76 min) and 0.066 min−1 (t1/2 = 10.50 min), respectively. The activation energy of the photodegradation process calculated from the Arrhenius equation was 10.6 kJ/mol. A positive ΔG value was obtained for the MNZ photodegradation by the STZZ photocatalyst that contained a positive ΔH and a negative ΔS (−0.2039 kJ/mol).