Removal of azo dyes by photochemical process

The effluents from textile waste waters cause the generation of toxic andcarcinogenic aromatic amins in the case of uncontrolled anaerobic conditions inaddition to aesthetic problems. In recent years advanced oxidation processes which arecapable of mineralizing organic compounds to CO2, H2O and inorganic salts ordestructing into biodegradable products have been developed.In this study, the degradation of C.I. Reactive Black 5 diazo dye used widely intextile industry was investigated by Photo-Fenton (Fe2+/H2O2/UV), Fenton (Fe2+/H2O2)and H2O2/UV processes in terms of decolorization and COD removal. The effect ofconcentrations of Reactive Black 5, H2O2, Fe2+ and temperature on the color and CODremoval have been examined. Experiments were conducted in a magnetic stirredphotoreactor and a UV lamp emitting 254 nm wavelength at 8 W was used as a lightsource. Experiments were planned by response surface methodology (RSM) which isone of the experimental design methods. Optimum conditions were determined by usingnumerical optimization method of RSM. Color and COD removal increased as H2O2and Fe2+ dosages increased but decreased with the increase of initial RB5 concentration.