The efficiency of UV/S2O8 2- photo-oxidation process in the presence of Al2O3 for the removal of dexamethasone from aqueous solution: kinetic studies.

Abstract

This study aimed to investigate the efficiency of the UV/S2O8 2- photocatalytic process in the presence of Al2O3 nanoparticles for the removal of dexamethasone from aqueous solution. In this experimental study, the variables pH, persulfate concentration, initial concentration of dexamethasone, the catalyst dose were studied in order to investigate the process efficiency. Furthermore, the efficiency of UV/S2O8 2- in the presence and absence of catalyst was investigated. The Al2O3 nanoparticle catalyst was characterized using X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) analyses and scanning electron microscopy (SEM) image. The results showed that a decrease in pH and the initial concentration of dexamethasone increased the process efficiency. Given the increased concentrations of the persulfate and Al2O3, the removal efficiency was partially increased. In UV/S2O8 2-/Al2O3 under optimum conditions (pH = 3, t = 30 minutes, dexamethasone concentration = 20 mg/L, 0.5 mM of persulfate, and UV radiation = 55 watts), 94% of the dexamethasone was removed. The kinetic response showed that the reaction data corresponded to the pseudo-first-order kinetic model. The results showed that the UV/S2O8 2- photochemical process can efficiently remove dexamethasone from aqueous solution in the presence of Al2O3 catalyst and the mineralization efficiency reached about 98%. Therefore, this process is recommended due to its high efficiency and availability for the removal of pharmaceutical compounds.