Influence of varying reacting conditions in the degradation of azo dye using immobilized TiO2 photocatalyst

In Malaysia, most colored wastewater from dyeing factories is discharged to the environment causing serious problems. In this paper the influence of several reacting conditions, i.e. H2O2, pH, Ultraviolet (UV) intensity and dye concentration, on the performance of the immobilized system is discussed. The pH of the solution was varied from 3 to 11 while H2O2 concentration tested was from 10(-4) M to 5 x 10(-2) M. UV was tested at 365 nm and 254 nm, while dye concentration ranged from 2.5 x 10(-4) M to 10(-3) M. The influence of the reacting conditions was assessed based on absorbance. Using an OG concentration of 10(-3) M, the degradation increases from 17.8% to 49.7%. Optimum concentration of H2O2 was found to be 5 x 10(-3) M for degradation. Increasing the intensity of the UV light via shorter light wavelength also improves the performance of the system. Increasing the concentration of the dye reduces the overall performance of the system. Using the dye concentration of 2.5 x 10(-4) M (H2O2 = 10(-2) M, lambda = 254 nm, pH = 11), gives a degradation of 93.2%. At dye concentration of 10(-3) M, the performance was reduced to 53.1%.