Application of ozonation on the removal of reactive red 198 dye at alkaline condition

ABSTRACT

Dyes are the most important pollutants of textile industries which have complex structures as well as toxic, carcinogenic, teratogenic and nonbiodegredable properties. This research was performed to compare the efficacy of removal and mineralization of Reactive Red 198 dye at alkaline and neutral pH. The effect of different pH 7,9,10 and 11 in dye and COD removal from 250 mg/1 aqueous solution of RR198 was evaluated. Dye removal efficiency was measured by UV-vis spectrophotometer and data were analyzed using SPSS 16, via statistical tests including One-Way ANOVA. COD removal efficiency was also measured by closed reflex method. Dye removal efficiency was higher than 96% in all different types of pH and also showed significant difference in different time intervals [P<0.05]. COD removal was lower than dye removal and in different types of pH 7, 9, 10 and 11 which after 60 minutes of reaction reached to 31, 40, 43 and 53% respectively. From the collected data it is obvious that rapid dye removal is due to the reaction of both molecular ozone and free radicals with dye molecules but more COD was removed only after the generation of hydroxyl radicals via pH elevation