The photocatalytic degradation of a textile dye, reactive red 2 in presence
of sunlight using TiO2 and ZnO as photocatalysts is reported. The experime
ntal 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 efficien
cy was found to be more with TiO2. ZnO decomposes on prolonged irradiation
while TiO2 is not photocorrosive. The percent degradation of the dye is hig
h for both the catalysts at an optimum concentration of the catalysts. The
first order rate constant is found to increase with decreasing dye concentr
ation.