Photocatalytic degradation of ciprofloxacin antibiotic in water by biosynthesized silica supported silver nanoparticles.

This study reports photocatalytic degradation of ciprofloxacin (CIP) in the presence of silver nanoparticles impregnated over amorphous silica extracted from rice husk through a green approach using Melia Azedarach fruit extract. Various analyses such as X-ray diffraction analysis (XRD), Fourier-transform infrared (FTIR) spectroscopy, and field emission scanning electron microscopy (FESEM) were employed to characterize the obtained nanocomposite. Afterward, the photocatalytic activity of the nanocomposite was studied in the removal of CIP from an aqueous solution under natural sunlight irradiation. Moreover, the effect of various parameters such as solution initial pH (3–11), reaction time (30–180min), and catalyst loading (0.03–0.12 g) on degradation efficiency were studied by applying a design of experiment (DOE) methodology. The results indicated the successful synthesis and deposition of Ag nanoparticles over amorphous silica. The results of degradation experiment confirmed the acceptable performance of Ag/silica nanocomposite in photo-degradation of CIP. According to the experimental design, both catalyst loading and reaction time are highly significant; whereas the initial pH is not significant compared to other factors. Moreover, the optimal conditions were determined to be initial pH = 6.7, reaction time = 180 min, and catalyst loading of 0.12 g. By applying these optimal conditions, degradation efficiency reached to 98%. Moreover, the results of kinetic study revealed that the photo-degradation of CIP in presence of Ag/silica nanocomposite obeys a first-order kinetic model. The Ag/silica nanocomposite exhibited a high level of stability as the nanocomposites could preserve their stability after three sequential degradation cycles. [Display omitted] [ABSTRACT FROM AUTHOR]