Solar photocatalytic degradation of azo dye in aqueous TiO2 suspension assisted by Fresnel lens

Abstract

Solar TiO2 photocatalytic process assisted by a Fresnel lens was investigated for treating an azo dye wastewater of Acid Orange 10 (AO10). Response surface methodology (RSM) was employed to assess the effect of critical process parameters (including initial pH of wastewater, concentration of TiO2, and reaction time) on treatment performance in terms of COD and TOC degradation efficiency. Optimized reaction conditions based on the analysis of RSM were established under an initial pH of 6.0, a concentration of TiO 2 of 1 g/L, and a reaction time of 2 h for reaching a 90 COD and TOC degradation of AO10 wastewater. With the assistance of Fresnel lens, the TOC degradation rate of AO10 wastewater increased significantly from 0.606 h -1 and 0.289 h-1 to 1.477 h-1 and 0.866 h -1 in summer (June) season (UV280-400 nm nm: 39.9-44.8 W/m2) and winter (December) season (UV280-400 nm nm: 23.9-26.9 W/m2), respectively. This could be mainly due to the concentrating effect of Fresnel lens for solar energy, resulting in an increase of 2∼2.5 times of solar light intensity and a raising heat irradiation in terms of 10∼15 °C of wastewater temperature. These results revealed that solar energy could be concentrated effectively by using Fresnel lens and showed a significant promoting effect on the TiO2 photocatalytic degradation of dye wastewater. © 2012 Wen-Shiuh Kuo and Wen-Yu Chen.