Degradation of magenta dye using different approaches based on ultrasonic and ultraviolet irradiations: Comparison of effectiveness and effect of additives for intensification

The conventional chemical oxidation methods have not been very successful for the treatment of dyes due to higher stability against the oxidizing agents. The present work investigates the application of an improved treatment approach based on the ultrasonic and ultraviolet irradiations for treatment of dye containing wastewaters. Magenta dye, which is commonly used in textile industries, has been used as a model compound. Initially, the experiments have been performed using individual operation of ultrasonic and ultraviolet irradiations. Studies related to effect of concentration revealed that the extent of degradation increased with an increase in the concentration of dye solution till an optimum loading. Intensification of the extent of degradation using ultrasonic irradiation has been investigated using different additives such as NaCl, TiO2, air and starch. Also the efficacy of combined treatment approaches based on different approaches involving ultrasound, ultraviolet irradiation and additives for the removal of magenta dye from the aqueous solution have been evaluated. For the use of additives, maximum intensification was achieved for TiO2 followed by use of NaCl and least effect was observed for starch. For the combined treatment approaches, the maximum extent of degradation (98.8%) and maximum COD removal (94.0%) has been obtained for the combination of ultrasound with 1 g/L TiO2 and air. The present work has clearly demonstrated the efficacy of combined treatment approaches for removal of dyes from the wastewater.