Ru–TiO₂ semiconducting nanoparticles for the photo-catalytic degradation of bromothymol blue

Photo-catalytic degradation of bromothymol blue (BTB) in an aqueous medium by Ru–TiO₂ using UVC (254 nm) irradiation was investigated for a pH range of 4.0–8.0. The liquid impregnation method was used to synthesize 0.2, 0.4 and 0.8 % ruthenium doped TiO₂ (Ru–TiO₂) nanoparticles. The characterizations of resulting nanoparticles were done using X-ray diffraction, scanning electron microscopy, fourier transform infrared spectroscopy, transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy analysis. The crystallite sizes of doped and undoped nanoparticles were determined from X-ray diffraction spectra using Scherrer equation. The average crystallite size of undoped TiO₂ was found to be 17.00 nm, whereas the crystallite sizes of 0.2, 0.4 and 0.8 % Ru–TiO₂ were 16.67, 15.70 and 14.40 nm respectively. The TEM images confirm the particle sizes to be 10–40 nm. Pseudo-first order rate constants (k_obs) determined were found to decrease with increase in pH. The effect of BTB Concentration, catalyst dosage, a percentage of doping of photo catalyst, pH and UV light intensity of BTB on the degradation rate were also examined.