Sonochemical degradation of the artificial sweetener acesulfame in aqueous medium and identification of transformation products

The sonochemical degradation of acesulfame (ACE), a widely used artificial sweetener, was investigated. The impact of power density (40 and 71 W/L), initial ACE concentration (1.5-30.6 & mu;\M), and initial solution pH (3-9) for the elimination of the target pollutant from water was studied. It was found that nearly complete degradation of ACE was achieved within 120 min of treatment under conditions suitable for high production of free radicals. Degradation follows a pseudo-first order kinetic model. Coupling sonochemical degradation at optimal conditions with sodium persulfate (0.2-1.0 mM) enhanced the rate of ACE oxidation by six times. The influence of water complexity was also examined; the natural occurrence of humic acid in the water matrix reduced the degradation rate, despite the fact that at least 42 % of ACE removal was achieved. Finally, LC-QToF-MS was used to evaluate the generated transformation products (TPs). Using HRMS suspect and non-target screening, seven ACE TPs were identified, and their time-trend formation profiles showed a rising trend throughout the experiment. According to the ECOSAR model, most of the identified transformation products exhibited lower toxicity than acesulfame, with one notable exception that was classified as harmful due to its acute toxicity on fish and green algae.