Sonochemical degradation of perfluorinated chemicals in aqueous film-forming foams

Lucia Rodriguez-Freire; Nerea Abad-Fernández; Reyes Sierra-Alvarez; Christiane Hoppe-Jones; Hui Peng; John P Giesy; Shane Snyder; Manish Keswani

doi:10.1016/j.jhazmat.2016.05.078

Sonochemical degradation of perfluorinated chemicals in aqueous film-forming foams

J Hazard Mater. 2016 Nov 5:317:275-283. doi: 10.1016/j.jhazmat.2016.05.078. Epub 2016 May 27.

Authors

Lucia Rodriguez-Freire¹, Nerea Abad-Fernández², Reyes Sierra-Alvarez³, Christiane Hoppe-Jones³, Hui Peng⁴, John P Giesy⁴, Shane Snyder³, Manish Keswani⁵

Affiliations

¹ Department of Materials Science and Engineering, The University of Arizona, P.O. Box 210012, Tucson, AZ, USA; Department of Chemical and Environmental Engineering, The University of Arizona, P.O. Box 210011, Tucson, AZ, USA.
² Department of Chemical Engineering and Environmental Technology, EII, Sede Mergelina, Universidad de Valladolid, Valladolid, Spain.
³ Department of Chemical and Environmental Engineering, The University of Arizona, P.O. Box 210011, Tucson, AZ, USA.
⁴ Toxicology Centre, University of Saskatchewan, 44 Campus Drive, Saskatoon, SK S7N 5B3, Canada.
⁵ Department of Materials Science and Engineering, The University of Arizona, P.O. Box 210012, Tucson, AZ, USA. Electronic address: manishk@email.arizona.edu.

PMID: 27295064
DOI: 10.1016/j.jhazmat.2016.05.078

Abstract

Aqueous film-forming foams (AFFFs) are complex mixtures containing 1-5% w/w fluorocarbons (FCs). Here, we have investigated degradation of two commercial AFFF formulations, 3M and Ansul, using sound field at 500kHz and 1MHz, with varying initial concentrations ranging from 200 to 930× dilution. The foams were readily degraded by 1MHz, with percentage of defluorination ranging from 11.1±1.4% (200× dilution of 3M) to 47.1±5.8% (500× dilution of Ansul). Removal of total organic carbon (TOC) ranged from 16.0±1.4% (200× dilution Ansul) to 39.0±7.2% (500× dilution Ansul). Degradation of AFFF was affected by sound frequency with rates of defluorination 10-fold greater when the frequency was 1MHz than when it was 500kHz. Mineralization of TOC was 1.5- to 3.0-fold greater under 1MHz than 500kHz. Rate of fluoride release was 60% greater for the greatest initial concentration of FC in Ansul compared to the least initial concentration. While the rate of mineralization of AFFF was directly proportional to the initial concentration of Ansul, that was not the case for 3M, where the rates of mineralization were approximately the same for all three initial concentrations. Results of the study demonstrate that sonolysis is a promising technology to effectively treat AFFFs.

Keywords: Defluorination; Megasonic; Perfluorocarbons; Sonolysis; Ultrasonic.