Photodegradation of N-Methyldiethanolamine over ZnO/SnO2 coupled photocatalysts

A photocatalyst semiconductor can be used to remove organic pollutants from wastewater in the presence of UV light. In this research, coupled Zn O/SnO 2 semiconductors with 1:1 and 2:1 ratios were prepared using the co-precipitation method. The prepared coupled ZnO/SnO2 photocatalyst was tested towards the photodegradation of simulated N-Methyldiethanolamine (MDEA) under U V-irradiation (λ = 365 nm, 100 V, 6 W). The ZnO/SnO 2 was characterized using UV diffused reflectance spectroscopy and X-ray diffraction. The band gap energy for ZnO/SnO2 (ZS) catalyst calcined at 200° C, 400° C, 600°C and 900°C were 3.22, 3.13, 3.12 and 3.07 eV, respectively, while for Z2S were 3.71, 3.28, 3.16, and 3.14 eV, respectively. XRD results indicated that ZS and Z2S catalysts possessed mixed phases of ZnO, SnO2 and Zn2SnO4 at a calcinations temperature above 600° C. The ZnO/SnO2 (2:1) catalyst, which was calcined at 600°C for 9 hours, gave the optimum percentage photodegradation of MDEA with 39.18%. The percentage degradation of MDEA was measured using ion chromatography with retention time at the measured peak of 4-5 minutes. The optimum system was applied on the photodegradation of MDEA in petroleum wastewater. The percentage degradation of MDEA in petroleum wastewater was 23.38 %. © Sharif University of Technology, December 2010.