Comparative Activity of Undoped TiO2 and 5% N-TiO2 for Photocatalytic Degradation of Indigo Carmine Dye

Abstract

TiO2 was synthesized by Sol-gel method and doped by Impregnation of Nitrogen from Ammonium Chloride to obtain 5% 2 N-TiO2 . The undoped TiO2 and N-doped TiO2 photocatalysts were characterized by Fourier Transform Infrared (FTIR) Spectroscopy, X-Ray Diffraction (XRD) Crystallography and Scanning Electron Microscopy (SEM). Investigation of the activities of the photocatalysts for degradation of Indigo carmine dye in aqueous solution was carried out at different operating conditions of pH, temperature, catalyst concentration and dye concentration under aeration and UV-irradiation using a 20 Watt UV lamp in a specially constructed reactor made up of four compartments. The dye degradation reaction was monitored on a N4S UV-Spectrophotometer at 290 nm. The FTIR results attested the presence of N-H, Ti-O-Ti, Ti O, H-O-H, O-H functional groups in the catalysts. The XRD Crystallography results show that 5% N- TiO2 catalyst contains a mixture of anatase and rutile phase compared to undoped TiO2 which contains pure anatase phase. The SEM results show decrease in particle size when TiO2 was doped with Nitrogen. The degradation rate was found to comply with first order kinetics and optimum degradation was attained at the same pH and temperature of 3 and 40 oC respectively for both photocatalysts. However, the dye and catalyst concentrations where optimum degradation was observed for 5 % N-TiO2 and undoped TiO2 were found to be 20 ppm, 0.025 g/l and 12.5 ppm, 0.05 g/l respectively. Percent degradation in the presence of both UV- Irradiation and catalyst was calculated to be 28.5 % and 34.14% for TiO2 and 5% N- TiO2 respectively. The percent degradation result shows a higher efficiency on 5% N- TiO2 than undoped TiO2.