Degradation of reactive azo dye by UV/peroxodisulfate system: an experimental design approach

In the present study, UV and UV/S2O82- have been applied to decolorize and mineralize organic dye C. I. Reactive Red 45 (RR 45) in aqueous solution. The rate of color removal was studied by measuring the absorbance at the characteristic wavelength while mineralization rates were obtained on the basis of total organic carbon (TOC). A statistical study of the process was performed using an experimental design method, particularly a response surface methodology (RSM) hexagonal design. Optimal operating conditions were established; pH 5 to pH 7 and [K2S2O8] = 15 mM. A complete color removal was achieved in all studied combinations of process parameters, while almost complete mineralization can be achieved at established optimal process conditions. According to the developed statistical model of the process and performed kinetic study, experimental data were fitted into a model of homogeneous system.