Removal of rhodamine B by ozone-based advanced oxidation process

The oxidation of rhodamine B in aqueous solution by conventional ozone process and the advanced ozone-based oxidation processes was investigated. The reaction conditions such as ozone dosage, initial concentration of the dye and pH in ozone process were optimized. The decolorization rate of rhodamine B increased with the ozone dosage but decreased with the initial concentration of rhodamine B. Three oxidative processes including UV/ozone, US/ozone and ozone systems were assessed to select the most appropriate oxidative process in terms of rhodamine B aqueous solution treatment and special emphasis was laid on the effect of reaction pH in the three methods. It was found that in all the three methods, the acid condition can promote the oxidation process. The UV/ozone process was the best ozone-based oxidization process, with the decolorization efficiency of 99.78% and COD removal rate of 47.43% after 15 min treatment. The pseudo-first order kinetics was found to fit all the ozone-based processes, with regard to the decoloration and degradation reactions.

► Ozone was successfully used in the treatment of rhodamine B.
► Single ozone, UV/ozone and US/ozone methods were researched and compared.
► The oxidation mechanisms of three methods were also analyzed.
► UV/ozone is the best ozone-based oxidization process.
► All ozone-based processes obey the pseudo-first order kinetics.