Gamma-radiation induced decolorization and degradation on aqueous solutions of Indigo Carmine dye

A reactive dye indigo carmine (IC) in aqueous solutions was irradiated at doses of 0.1-5 kGy. Change of absorption spectra, colorimetric study, chemical oxygen demand (COD), total organic carbon (TOC) and pH variation were carried out and studied. It was found that the absorption band located at lambda = 611 nm decreased more rapidly than the UV visible bands when irradiation dose increases. The degree of decolorization and the value of color difference (a dagger E*) increases quadratically with increasing the value of radiation dose. The COD reduction for the dye solutions was approximately 96% at 5 kGy. Finally, based on different spectrophotometric measurements carried out in this work showed that the kinetic degradation of indigo carmine is pseudo-first order. We have also demonstrated that colorimetric study applied to a given solution could be used as a quantitative method for kinetic behavior study.