Degradation of Endocrine Disrupting Chemical Nonylphenol in Aqueous Milieu using High Frequency Ultrasound

In this work, we report the application of the high ultrasound frequency (278 kHz) to degrade nonylphenol (NP) as endocrine disrupting chemical (EDC). The degradation was performed under many experimental conditions. The effects of operating parameters such as: methanol as the type of solvent, initial NP concentration (in the limit of solubility 0.5 to 24.5 µmol.L-1), ultrasonic power (in the range from 20 to 100 W) and initial solution pH (3; 5.4; 10.2) as well as the effect of the bicarbonate ions on the degradation of NP were evaluated. Results indicated that the initial degradation rate increased slowly with the increase of the substrate concentration.The kinetic studies revealed that the sonodegradation process follows a pseudo-first-order model with the high correlation coefficient under different experimental conditions. In addition, the obtained results showed that ultrasound completely destroyed NP (8.1 µmol.L-1) after 120 min of sonication. pH had not a significant effect, due to the invariable molecular form of NP during the range of pH study, which was less than pKa of NP (10.7). Finally the results clearly demonstrated the significant intensification of sonolytic destruction of NP in the presence of bicarbonate, especially at lower pollutant concentrations. This behaviour is deleterious at high pollutant concentration.