Optimization of Reactive Blue 19 dye removal using ozone and ozone/UV employing response surface methodology

Abstract

This work reports the degradation of Reactive Blue 19 (RB19) dye using ozone and ozone/UV. The effects of operational parameters such as pH, ozone concentration and UV radiation were examined. A two factor with three levels factorial design was carried out and the interaction between variables was studied. Response surface methodology was applied in order to optimize ozone concentration, pH and UV radiation in terms of the half life time required for discoloration and/or mineralization of the solution. Equations of color and TOC half-life time with respect to operational conditions were determined. Contour plots and a desirability function were used to find the local points of optimization. Optimized reaction conditions were established as pH 8.26, UV radiation of 40 W and ozone concentration of 50 g Nm−3. A specific experiment was carried out under the optimal conditions where RB19 half life time was 1.59 min and TOC half life time was 30.98 min, confirming the agreement between model and experimental results. The obtained results confirm ozonation as a promising alternative for treatment of wastewater with a high content of recalcitrant reactive dyes.