Abstract

Dyes are the most important pollutants of textile industrial wastewaters which have complex structures, toxic, carcinogenic, teratogenic, nonbiodegredable properties. This research investigated reactive red 198 dye degradation. The effects of pH, ozone dosage and initial dye concentration on dye and its related chemical oxygen demand (COD) removal with ozonation process were evaluated. The result shows that increasing of pH from 4 to 10 led to increase of the dye removal efficiency from 75 to 81 within 10 minutes. Also, the results revealed that elevation of the inlet gas flow rate onto ozone generator up to 0.5 lit/min led to increase of dye removal performance but, upper flow rates led to decreasing of dye removal efficiency. For initial dye concentrations of 100, 250 and 500 mg/1, the complete decolorization occurred after 10, 25 and 60 minutes, respectively. Also, the result represents that increasing of dye concentration led to decreasing of reaction rate constant from 0.205 min -1 to 0.08 min -1. The rate of COD removal was relatively lower than the decolorization rate so that, after 60 minutes of ozonation only 67 of initial COD removal occurred. The results of this research revealed that ozonation can be used as a promising process for this color and its related COD removal in which the best performance occurs at an alkaline pH. © IDOSI Publications, 2011.