ULTRASONIC IRRADIATION OF THE REMOVAL OF LINEAR ALKYLBENZENE SULPHONATES (LAS) FROM WASTEWATER

The effect of low frequency (20 kHz) ultrasonic irradiation on the removal of sodium Linear Alkylbenzene Sulphonates (LAS) from aqueous solutions has been investigated. Sonication of three different initial concentrations of LAS, 500 mu mol/l, 750 mu mol/l and 1000 mu mol/l, were performed. All experiments used a temperature of 30 degrees C, frequency of 20 kHz, power of 125 W, a batch time of 120 min and the pH was left uncontrolled. It was found that the main degradation of LAS at micromolar concentrations proceeded via a reaction with OH center dot radicals. The initial degradation rate increased with an increase in the surfactant concentration over the whole concentration range studied. The sonolysis of LAS showed a strong inhibition of H2O2 production at a higher concentration. Sonication of LAS in the presence of Br- suggested that OH center dot radicals induced degradation pathway was the dominating sonochemical degradation mechanism.