Degradation of ciprofloxacin by TiO2/Fe2O3/zeolite catalyst-activated persulfate under visible LED light irradiation

Abstract

The activation of persulfate (PS) by metal catalysts under visible light is expected to offer a promising oxidation reaction for the removal of contaminants from water. Herein, we investigated activated PS systems under visible light irradiation for the generation of reductive species to decompose ciprofloxacin (CIP). Improved PS activation using TiO₂/Fe₂O₃/zeolite ((n)TiFeZ) under visible light irradiation favorably leads the reaction to generate reductive radicals. The enhanced degradation efficiencies of the (n)TiFeZ–PS system for CIP removal was due to the extended absorbance in the visible-light region and improved space separation of photo-induced charge carriers. The (4)TiFeZ catalyst exhibited better performance for CIP removal as compared to the other samples. The CIP was completely degraded in 120 min using 1 g L⁻¹ (4)TiFeZ and 5.0 mM PS at pH 7.0. The characterization and electron paramagnetic resonance (EPR) of (n)TiFeZ suggested that CIP was mainly degraded by surface-adsorbed radicals generated from the reaction between PS and Fe(II) on the samples under visible light. The reductive systems coupled with (n)TiFeZ exhibited high CIP degradation efficiency and high potential for the decomposition of other antibiotic compounds.