Competition in sonochemical degradation of Naphthol Blue Black: Presence of an organic (nonylphenol) and a mineral (bicarbonate ions) matrix

Abstract

This study is dedicated to high frequency (278 kHz) sonolytic degradation of organic micropollutants in a complex aqueous medium. A model matrix composed of Naphthol Blue Black (an azoic dye, NBB), of Nonylphenol (an endocrine disrupting compound, NP) and of bicarbonate ions was investigated in order to evaluate the influence of NP and/or bicarbonate ions on the kinetics of NBB sonolysis.It was found that the NBB has no significant effect on the NP sonodegradation kinetics whereas the NP considerably decreases the NBB degradation rate. Furthermore it was highlighted the presence of bicarbonate ions is a way to reach a more efficient NBB degradation rate at low micropollutant concentrations, even in the presence of NP. These preferential sonodegradation rates were explained by the zone where the sonoreaction takes place, which was correlated to the physico-chemical properties of the studied molecules.It was also proved the kinetic model of sonolytic degradation of NBB is modified by the presence of bicarbonate ions; the most suitable model in this case is the Serpone's model which assumes the degradation of the compound in the gas/liquid interface and in the solution.