PFAS Degradation in Ultrapure and Groundwater Using Non-Thermal Plasma

Molecules

Marco Minella¹  Manuel Lai²  Dimitra Papagiannaki³  Rita Binetti³  Davide Palma⁴  Claire Richard⁴  Mohamad Sleiman⁴ 

[1] Department of Chemistry and Interdepartmental Centre Nanostructured Interfaces and Surfaces (NIS), University of Torino, Via Pietro Giuria 5, 10125 Torino, Italy;IRIS s.r.l., Via Papa Giovanni Paolo Secondo 26, 10043 Orbassano, Italy;SMAT S.p.A., Research Centre, C.so Unità d’Italia 235/3, 10127 Torino, Italy;Université Clermont Auvergne, CNRS, Sigma Clermont, ICCF, 63178 Aubière, France;

关键词: non-thermal plasma;    PFAS;    NO_x;    water treatment;    advanced oxidation processes;   

DOI  :  10.3390/molecules26040924

来源: DOAJ

【 摘 要 】

Perfluoroalkyl substances (PFAS) represent one of the most recalcitrant class of compounds of emerging concern and their removal from water is a challenging goal. In this study, we investigated the removal efficiency of three selected PFAS from water, namely, perfluorooctanoic acid (PFOA), perfluorohexanoic acid (PFHxA) and pefluorooctanesulfonic acid (PFOS) using a custom-built non-thermal plasma generator. A modified full factorial design (with 2 levels, 3 variables and the central point in which both quadratic terms and interactions between couple of variables were considered) was used to investigate the effect of plasma discharge frequency, distance between the electrodes and water conductivity on treatment efficiency. Then, the plasma treatment running on optimized conditions was used to degrade PFAS at ppb level both individually and in mixture, in ultrapure and groundwater matrices. PFOS 1 ppb exhibited the best degradation reaching complete removal after 30 min of treatment in both water matrices (first order rate constant 0.107 min⁻¹ in ultrapure water and 0.0633 min⁻¹ in groundwater), while the degradation rate of PFOA and PFHxA was slower of around 65% and 83%, respectively. During plasma treatment, the production of reactive species in the liquid phase (hydroxyl radical, hydrogen peroxide) and in the gas phase (ozone, NO_x) was investigated. Particular attention was dedicated to the nitrogen balance in solution where, following to NO_x hydrolysis, total nitrogen (TN) was accumulated at the rate of up to 40 mg^N L⁻¹ h⁻¹.

【 授权许可】

Unknown