Kinetic study on photocatalytic degradation of 4BS Azo dye over TiO2 in slurry

Adsorption and photocatalytic degradation of 4BS dye over fine particulate TiO2 are studied in an opened batch slurry reactor. The influences of mixing of solid-liquid and external diffusion on degradation rate are eliminated by increasing stirred rate. The adsorption experimental results indicate that pH and temperature of solution affect adsorption considerably, a Langmuir equilibrium adsorption isotherm can be used to described them. Meanwhile, catalyst dosage, reaction time, pH of solution, stirring speed, initial concentration, direct irradiation area, and illumination intensity of UV light can affect the reaction rate. Favorable pH for 4BS dye degradation is about 3.5, suitable dosage of catalyst is about 1.0 g (.) L-1. After numeric analysis to experimental data, a kinetics model is established; the rate constants are different for catalyst dosage in 0.5 g (.) L-1 or 1.0-6.0 g (.) L-1.