Sonochemical degradation of Rhodamine B in aqueous phase: Effects of additives

The effects of various additives such as iron (elemental, bivalent and trivalent), carbon tetrachloride, hydrogen peroxide, tert-btyl alcohol, salt (Na2SO4), sucrose and glucose on the sonochemical destruction of cationic dye, Rhodamine B (RhB), in aqueous phase were studied. Additionally, sonolytic degradation of RhB was investigated at varying initial dye concentration, power, pH and temperature. RhB can be readily eliminated by the ultrasound process, but even after long ultrasound irradiation times (240 min), more than 40% of chemical oxygen demand (COD) remained in the solution. Sonochemical degradation of RhB was strongly affected by initial substrate concentration, ultrasonic power, temperature and pH. The ultrasonic degradation of dye was enhanced by iron addition. The acceleration effect of iron on the destruction rate displayed the following order: Fe(II) > Fe(III) > Fe0. It was found that the degradation of the dye was accelerated with increased concentrations of CCl4 via the formation of oxidant chlorine species. It was observed that there was an optimum concentration of H2O2 and Na2SO4 for enhancing the degradation degree of RhB. In the presence of tert-butyl alcohol at low concentration, unexpectedly, the rate of dye degradation was accelerated. Very slow RhB degradation occurs if the sonolysis is carried out in the presence of high tert-butyl alcohol concentration. The slight decrease in the degree of RhB removal in the presence of high concentrations of sucrose and glucose is a clear indication that ultrasonic irradiation is a promising process for the removal of RhB from alimentary liquids containing sucrose and glucose.