Ultrasonic assisted photocatalytic process for degradation of ciprofloxacin using TiO2-Pd nanocomposite immobilized on pumice stone

Abstract Herein, Pumice (PM)-TiO2-Pd nanocomposite as an efficient catalyst was prepared by modified sol-gel method and used for sonophotocatalytic removal of ciprofloxacin (CIP). Various analyses were used to investigate the properties of the catalysts. Based on the SEM results, the TiO2 and Pd nanoparticles on the PM surface were immobilized regularly without aggregation. Also, the crystalline structure and functional groups of PM-TiO2-Pd nanocomposite were identified successfully by XRD and FTIR analyses. The bandgap energy of 2.52, 3.17, and 3.29 eV were calculated for PM-TiO2-Pd, PM-TiO2, and PM indicating higher sonophotocatalytic activity of PM-TiO2-Pd nanocomposite. 79.44 % of CIP was removed within 120 min of treatment time using in the optimum condition ([PM-TiO2-Pd] = 0.5 g/L, [CIP]0 = 20 mg/L and pH = 6). By adding radical scavengers like EDTA, CrO3, formic acid, and enhancers like K2S2O8 and H2O2 the degradation efficiency was as follows respectively: 37.72, 31.71, 28.29, 88.78, and 72.43%. The reusability and stability of the composite after four consecutive runs was decreased only 9.44%. Also, 8 intermediate byproducts generated under sonophotocatalytic degradation of CIP by PM-TiO2-Pd nanocomposite were identified.