Effects of TiO 2 Nanoparticles Synthesized via Microwave Assistance on Adsorption and Photocatalytic Degradation of Ciprofloxacin.

In this study, the optimal microwave-assisted sol-gel synthesis parameters for achieving TiO 2 nanoparticles with the highest specific surface area and photocatalytic activity were determined. Titanium isopropoxide was used as a precursor to prepare the sol (colloidal solution) of TiO 2 . Isopropanol was used as a solvent; acetylacetone was used as a complexation moderator; and nitric acid was used as a catalyst. Four samples of titanium dioxide were synthesized from the prepared colloidal solution in a microwave reactor at a temperature of 150 °C for 30 min and at a temperature of 200 °C for 10, 20, and 30 min. The phase composition of the TiO 2 samples was determined by X-ray diffraction analysis (XRD) and Fourier-transform infrared spectroscopy (FTIR). Nitrogen adsorption/desorption isotherms were used to determine the specific surface area and pore size distributions using the Brunauer-Emmett-Teller (BET) method. The band-gap energy values of the TiO 2 samples were determined by diffuse reflectance spectroscopy (DRS). The distribution of Ti and O in the TiO 2 samples was determined by SEM-EDS analysis. The effects of adsorption and photocatalytic activity of the prepared TiO 2 samples were evaluated by the degradation of ciprofloxacin (CIP) as an emerging organic pollutant (EOP) under UV-A light (365 nm). The results of the photocatalytic activity of the synthesized TiO 2 nanoparticles were compared to the benchmark Degussa P25 TiO 2 . Kinetic parameters of adsorption and photocatalysis were determined and analyzed. It was found that crystalline TiO 2 nanoparticles with the highest specific surface area, the lowest energy band gap, and the highest photocatalytic degradation were the samples synthesized at 200 °C for 10 min. The results indicate that CIP degradation by all TiO 2 samples prepared at 200 °C show a synergistic effect of adsorption and photocatalytic degradation in the removal process.