Kinetics and Mechanism of Low-Frequency Ultrasound Driven Elimination of Trace Level Aqueous Perfluorooctanesulfonic acid and Perfluorooctanoic acid

Publication date: Available online 29 May 2019Source: Chemical Engineering and Processing - Process IntensificationAuthor(s): Panda Debabrata, Sethu Vasanthi, Manickam SivakumarAbstractPerfluorooctanesulfonic acid (PFOS) and Perfluorooctanoic acid (PFOA) are the most investigated persistent organic pollutants due to their adverse health concerns and inertness in elimination. The wastewater treatment of PFOX (PFOS and PFOA) has been investigated by sonochemical method while implementing a 20-kHz probe-type sonicator with ultrasound power variance from 150 to 375 W. Highest degradation rate was achieved under optimum parameters such as PFOX initial concentration, ultrasound power level, solution pH and temperature. Complete removal of PFOX was obtained within 80 min of sonochemical treatment as exhibited by liquid chromatography-mass spectroscopy analysis. Change in the bulk phase temperature from the optimum value of 20 °C and the decline in ultrasound power demonstrated a detrimental effect on the degradation rate. The degradation rate enhanced with an increase in PFOX initial concentration from 20 to 220 pM, beyond which the rate declined. The reaction kinetics were observed to follow pseudo first order-up-to 400 pM and zero order kinetics beyond 400 pM of initial concentration. Following the degradation mechanism, PFOX is assumed to undergo thermal decomposition at bubble interfacial region along with pyrolysis of intermediates inside the cavity.Graphical abstr...
Source: Chemical Engineering and Processing: Process Intensification - Category: Chemistry Source Type: research