Degradation of textile dye by solar light using TiO2 and ZnO photocatalysts

The photocatalytic degradation of a textile dye, reactive red 2 in presence of sunlight using TiO2 and ZnO as photocatalysts is reported. The experimental studies have indicated complete decolourisation of the dye in a short period and degradation within 8 hr of irradiation. ZnO was found to be more effective in the removal of colour than TiO2 but the degradation efficiency was found to be more with TiO2. ZnO decomposes on prolonged irradiation while TiO2 is not photocorrosive. The percent degradation of the dye is high for both the catalysts at an optimum concentration of the catalysts. The first order rate constant is found to increase with decreasing dye concentration.