Application of ultrasound for degradation of benzophenone-3 in aqueous solutions

This paper reports the results of an experimental work on sonochemical degradation of benzophenone- 3 (BP3), one of the most commonly used ultraviolet (UV) filters whose disruptive effect on the endocrine system of various living beings has been demonstrated. Ultrasound irradiation is a promising advanced oxidation technology that has received considerable interest as an alternative for degradation of persistent organic pollutants through hydroxyl free radicals that are generated from the cavitation bubbles implosion. Taking into account the potential risk due to the presence of BP3 in the environment and its possible removal using ultrasound, the effect of operating parameters such us ultrasonic applied power, pollutant initial concentration, pH, the presence of gases (including ozone), inorganic anions and alcohols on the substrate removal was investigated. During sonochemical treatment, a higher pollutant degradation rate was achieved by increasing the power in a range of 40.2–80.1 W. Likewise, at lower benzophenone-3 initial concentrations, higher extents of degradation were observed, which could be explained by a heterogeneous kinetics model. Acidic pH enhanced the pollutant initial degradation by 21 %. Oxygen, ozone and bicarbonate ions affected positively the benzophenone-3 removal, while nitrogen, nitrate and chloride anions inhibited it. Measurements of concentration of hydroxyl free radicals indicated that by promoting OH∙ radical formation, the pollutant elimination rate can be increased.

Keywords
Advanced oxidation process; Benzophenone-3; Hydroxyl radicals; Sonochemical degradation; Water treatment