Degradation of sodium dodecylbenzene sulfonate in water by ultrasonic irradiation

Abstract

The potential of using ultrasonic irradiation for the removal of sodium dodecylbenzene sulfonate (SDBS) from aqueous solutions has been investigated. Experiments were performed at initial concentrations of 15, 30 and 100 mgl1, ultrasonic frequencies of 20 and 80 kHz, applied power values of 45, 75 and 150W and liquid bulk temperatures of 20, 40 and 60 1C. At the conditions in question, SDBS conversion was found to decrease with increasing temperature and initialsol ute concentration and decreasing power and frequency. Investigations using the radicalscavengers 1-butanol and KBr revealed that SDBS degradation proceeds through radical reactions occurring predominately at the bubble–liquid interface and, to a lesser extent, in the liquid bulk. Addition of NaCl or H2O2 had little or even an adverse effect on SDBS conversion. Conversely, addition of Fe2+ either alone or in conjunction with H2O2 (Fenton reagent) had a positive effect on degradation. Finally, shake flask tests with activated sludge were performed to assess the aerobic biodegradability before and after sonochemical treatment. At the conditions under consideration, the use of ultrasound enhanced the aerobic degradability of the substrate in question