Intensification of sonochemical decolorization of anthraquinonic dye Acid Blue 25 using carbon tetrachloride

Abstract

In this work, the influence of CCl 4 on the sonochemical decolorization of anthraquinonic dye Acid Blue 25 (AB25) in aqueous medium was investigated using high frequency ultrasound (1700 kHz). This frequency, reputed ineffective, was tested in order to introduce the ultrasound waves with high frequency in the field of degradation or removal of dyes from wastewater, due to its limited use in this field, and to increase the application of high frequency ultrasound wave in the field of environmental protection. The effects of various parameters such as the concentration of CCl 4, frequency (22.5 and 1700 kHz), solution pH, temperature and tert-butyl alcohol adding on the decolorization rate of AB25 was studied. The obtained results clearly demonstrated the significant intensification of AB25 decolorization in the presence of CCl 4. The enhancement effect of CCl 4 increased by decreasing temperature and by increasing the CCl 4 concentration. The pH has a significant influence on the bleaching of dye both in the absence and presence of CCl 4. The three investigated dosimeter methods (KI oxidation, Fricke reaction and H 2O 2 production) well corroborate the improvement of the sonochemical effects in the presence of CCl 4. The best sonochemical decolorization rate of AB25 in aqueous solution both in the absence and presence of CCl 4 is observed to occur at 1700 kHz compared to 22.5 kHz. The sonochemical oxidation of CCl 4 generates oxidizing species in the liquid phase that are highly beneficial for oxidation of hydrophilic and non-volatile pollutant, such as dyes, because they are less susceptible to free radical attack due to lower stability of the generated free radicals.