Enhanced treatment of perfluoroalkyl acids in groundwater by membrane separation and electrochemical oxidation
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2020-10-23 |
| Journal | Chemical Engineering Journal Advances |
| Authors | Ălvaro Soriano, Charles E. Schaefer, Ane Urtiaga |
| Institutions | Universidad de Cantabria, CDM Smith (United States) |
| Citations | 69 |
Abstract
Section titled âAbstractâThis work explores the treatment of poly- and perfluoroalkyl acids (PFAAs) in groundwater by coupling membrane separation and electrochemical oxidation (ELOX). A process system engineering approach based on modelling and empirical data was followed. Two nanofiltration (NF90) and reverse osmosis (BW30) membranes were characterized for treating an electrolyte (NaCl and CaSO4) mixture of perfluorocarboxylic acids (PFCAs) containing PFOA, PFHpA, PFHxA, PFPeA and PFBA with initial concentrations of 10 ”g Lâ1 each. Membrane surface charge shielding and concentration polarization negatively influenced NF90 performance, and the BW30 membrane was selected. Electrochemical oxidation with boron doped diamond anodes treated the PFCAs mixture amended with PFOS and 6:2 FTSA, emulating previously pre-concentrated feed and non-preconcentrated feed conditions. Working at different current densities (J) between 20 and 350 A mâ2, the removal of PFOA, PFOS and 6:2 FTSA followed first order apparent kinetics, although shorter chain PFCAs initially showed increasing trends because of their simultaneous electrogeneration and degradation. Overall, ÎŁPFAA electrolysis followed first order kinetics linearly correlated to J in the full range of testing. Unexpectedly, PFAAs electrolysis was faster for the low conductive non-preconcentrated feed, a result that was ascribed to the enhanced direct electron transfer mechanism resulting from the higher cell voltage. For 99.9% PFAAs removal, the total specific cost of treatment was minimized using a cascade of four RO stages and ELOX treatment of the concentrate, to reach ÎŁPFAA below the Health Advisory Levels recommended by the USEPA in drinking water (<70 ng Lâ1 sum of PFOA and PFOS).
Tech Support
Section titled âTech SupportâOriginal Source
Section titled âOriginal SourceâReferences
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