Decolorization of the textile azo dye Reactive Orange 16 by the UV/H2O2 process

The photochemical decolorization of C.I. Reactive Orange 16 (RO16), a reactive textile azo dye, by the UV/H2O2 process was studied using a batch photoreactor with UV lamps emitting at 253.7 nm. Complete decolorization of 50.0 mg dm(-3) initial dye concentration was achieved in less than 6 min under optimal conditions (25 mM initial peroxide concentration, at pH 7.0 and with a UV light intensity of 1950 mu W cm(-2)). The effects of experimental variables, such as initial pH, initial concentration of H2O2, initial dye concentration, and the intensity of UV light were studied. The highest decolorization rates were realized at a peroxide concentration in range from 20 to 40 mM, above which decolorization was inhibited by the scavenging effect of the peroxide. The decolorization was more efficient in neutral pH values. The efficiency of the process was improved with lower initial dye concentrations and at higher intensities of UV light.