REMOVAL OF COLOR AND COD FROM C.I.ACID RED 52 AQUEOUS SOLUTION BY NaOCl AND H2O2 OXIDATION PROCESSES

Removal of color from aqueous solution of C.I. Acid Red 52, a xanthene dye was investigated by chemical coagulation with Al2(SO4)3, AlCl3, FeSO4, FeCl3 and advanced oxidation process (AOP) employing NaOCl and H2O2. Coagulation experiments yielded no color removal whereas studies with AOP resulted in good color removal. Oxidation with NaOCl produced a color removal of 87% and a COD removal of 53% at a pH of 9.5 whereas H2O2 exhibited a color removal of 98% and COD removal of 67% at a pH of 12. Color removal from the dye molecule subjected to oxidation with oxidants NaOCl and H2O2 may be delineated through step wise oxidative degradation of the chromophoric groups in the dye molecule to colorless hydroxyl, carbonyl, ozonide, carboxylic acids residues and finally to CO2 and H2O depending on the nature, concentration and contact time of the oxidant used and also on the pH of the medium. A probable mechanism of chemical degradation of the dye by AOP is also proposed.