Among the methods for water and wastewater treatment and decreasing their contaminants, photocatalytic degradation by semiconductors is a new, effective, rapid and destructive technique for this purpose and TiO 2 is considered to be one of the best candidate photocatalysts. On the other hand, carbon nanotube–inorganic hybrid materials are a new 35% and 48.3% decolourization was observed for TiO 2 and TiO 2 -CNT hybrid, respectively. The effect of some parameters such as pH, the amount of photocatalyst and initial dye concentration was also examined employing TiO 2 -functinalized CNT hybrid as photocatalyst. The effect of initial concentration was obtained with different initial concentrations (10–25 ppm). To study the effect of photocatalyst dosage, the photocatalyst loading in the dispersion was varied between 40-120 ppm. The effect of pH of the solution was examined in the pH range of 2–12. The best results for decolourization was obtained in acidic solution (pH=2), initial dye concentration 15 ppm, photocatalyst dosage 80 ppm and was equal to 93.5% after 120 min. The amount of dye adsorbed was higher in acidic medium and decreased with increasing initial pH. In different cases, the semi-log plot of dye concentration versus time was linear, suggesting first order reaction. First order reaction rate constant was calculated equal to 2.2×10 -2 min -1 (R 2 =0.959) at best performance of decolourization. Key Words: TiO 2 , CNT, photocatalyst, acid blue 92, hybrid
