Decolorization and mineralization of C.I. direct red 28 azo dye by ozonation

Abstract

AbstractThis study evaluated the efficiency of ozonation for removal of color and chemical oxygen demand (COD) of Congo red, as an anionic dye was selected due to the complex chemical structure with di-azo aromatic group and extended application in the textile industry. The effect of ozonation time on the rate of COD removal, mineralization and rate of decolorization were studied and the result was analyzed in terms of COD and color removal efficiency. Intermediate and final by-products formed during ozonation were identified by ion chromatography (IC). Dye decomposition rate was observed by UV–vis spectroscopy. The removal of COD and color of Congo red by ozonation was performed in a batch reactor with constant ozone flow rate and concentration of 5 g/hr and 55.5 mg/L, respectively. Dye concentration was 1,500 mg/L. Decolorization and degradation of dye sample were carried out with a certain time interval and analyzed immediately. The COD and color removal efficiencies increase at specified time of ozona...