Degradation of sulfamethoxazole in water by AgNbO 3 photocatalyst mediated by persulfate.

In this paper, silver niobate (AgNbO 3 ) material was synthesized by a solid-state reaction. AgNbO 3 was characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), UV-visible diffuse reflectance spectroscopy (DRS), and Brunauer-Emmett-Teller (BET) measurement. The photocatalytic activity of AgNbO 3 was investigated in degradation of sulfamethoxazole (SMX) under visible light, which is a widely used antibiotic with significant threats towards health and aquatic organisms. Persulfate (PS) oxidant was found to improve the efficiency of the proposed photocatalytic removal of SMX by AgNbO 3 . The different operational parameters in the AgNbO 3 /PS/Vis system were investigated. The best photocatalytic performance was achieved with 0.5 g L -1 AgNbO 3 , 1.0 mM PS, and pH = 5.0 as the optimal conditions, achieving 98% of SMX degradation after 8 h of visible-light irradiation. Scavenger and electron spin resonance (ESR) experiments were carried out to identify the major reactive species in the SMX degradation and to propose the photocatalytic mechanism by the AgNbO 3 /PS/Vis system. The photodecomposition was found to be majorly caused by holes and ˙O 2 - species, with ˙OH and SO 4 ˙ - radicals contributing to improve the photocatalytic process. The AgNbO 3 catalyst was stable and reusable with efficient photocatalytic activity in three successive recycling experiments and its XRD patterns remained virtually unchanged. The reported process of PS activation by the AgNbO 3 photocatalyst is promising for visible-light application in remediation of antibiotic-contaminated water.