SYNTHESIS OF TiO_2-BASED PHOTOCATALYSTS BY DIFFERENT MAGNESIUM DOPING AND COMPARABLE STUDY OF THEIR PHOTODEGRADATIVE PERFORMANCE FOR CIPROFLOXACIN

摘要

Due to the high efficiency, stability and low cost, alkaline-earth metal doping has proven to be a promising method to modify TiO_2-based photocatalysts. In this work, Mg powder, MgO, Mg(OH)_2, Mg(NO_3)_2, MgCl_2, MgSO_4 and Mg(OH)_2 -MgCO_3 -doped TiO_2 were prepared by a facile solid-state method. The as-prepared photocatalysts were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), UV-Vis diffuse reflectance spectra (UV-Vis DRS) and nitrogen adsorption-desorption isotherms. The enhancement of visible light absorption and the decrease in specific surface area by Mg-doping have been observed. Impurity level from Mg ions" doping is responsible for the enhanced absorption of light. The photo-catalytic activities of as-prepared samples were evaluated by degradation of ciprofloxacin (CIP) under visible light irradiation. Result shows that the photocatalytic activities of various Mg compound-doped samples are quite different. The degradation ratios of different Mg-doped photocatalysts are in the order of Mg(NO_3)_2 > MgSO_4 > Mg powder > MgCl_2 > MgO > Mg(OH)_2 > Mg(0H)_2 MgCO_3 being due to the various effects from different anions in Mg salts. Our work highlights the simple way to modify TiO_2 photocatalyst for practical use.