Azo dyes are the largest group of dyeswhich are used for dyeing in thetextile industry. The worldwide high level of production and use of dyes cause colored wastewater and water contaminationthat is major issue of morbidity and mortality[1].The photocatalytic activity of the nanocomposites and nanoparticleshave been reported on photodegradation of 4-amino azo benzene (4-aab)aqueoussolutions] 2,3[. Here,TiO₂/CdSnanocompositespreparedvia a new method andphotocatalytic degradation of the dye in presence ofTiO₂nanoparticles and TiO₂/CdSnanocomposites under UV irradiation is presented. Several parameters such as catalyst concentration, pH, and UV irradiationtime were studied for optimization of degradation yield.The best catalytic activity towards4-aabphotocatalytic degradation, 16mg of TiO2/CdS nanocomposites in4-aab aqueoussolutions(100ml)is obtained. Alsophotodegradation yield 89%for5ppm solution of4-aabin the presence of TiO₂/CdSnanocompositesat 5pH was achieved in 40 min, comparing this result whitTiO2nanoparticles asphoto-assisted process shows photodegradation yield 11% higher than what obtained for TiO2 nanoparticles in the same irradiation time and equal amount of nanocatalyst. Moreover, the rate constants calculated at different reaction conditions.Due to lower band-gap energies of the TiO2/CdS nanocomposites comparing to pure TiO2 nanoparticles, TiO₂/CdSnanocomposites upon excitation would beproduce more electron–hole pairs, which should result higher photocatalytic activities[4].This result confirmedTiO₂/CdSnanocompositesrequirelower energy than TiO2 nanoparticles.
