Factors Influencing Pharmaceutical and Personal Care Product Degradation in Aqueous Solution Using Pulsed Wave Ultrasound

Continuous wave (CW) and pulsed wave (PW) ultrasound were used to degrade pharmaceuticals (carbamazepine, ibuprofen, acetaminophen, sulfamethoxazole, and ciprofloxacin), and personal care products (propyl gallate and diethyl phthalate). These compounds, covering a range of physicochemical properties and a diversity of structures, were explored to determine if and how PW ultrasound is advantageous to CW ultrasound. Degradation rates by PW ultrasound were faster for smaller compounds and slower for larger compounds than that under CW ultrasound. The addition of a bulk solution (OH)-O-center dot trapping agent, acetic acid, to PPCP solutions indicates that the fraction of degradation occurring in bulk solution is positively correlated with the molar volume of the compound. Overall, smaller PPCP compounds with molar volumes less than 130 mL/mol are able to more readily diffuse to bubble interfaces and are impacted most by pulsing ultrasound.