Breakdown kinetics of PFAS utilising a non-thermal plasma bubble column

The environmental recalcitrance of per- and polyfluoroalkyl substances (PFAS) requires advanced water treatment processes to destroy these pollutants in contaminated waters. A synergistic treatment approach applying non-thermal plasma discharges in argon and bubble transport was investigated to destroy a structurally diverse suite of PFAS in various compositions and liquid matrices at treatment volumes up to 25 L. The trends in removal kinetics showed the treatability of PFAS correlated with the length of the perfluorinated carbon chain, with high removal rates (>99%) achievable for longer chain PFAS species. Breakdown products consisted primarily of inorganic fluoride ions and trace quantities of shorter chain species. Higher initial concentrations and larger bubble surface area (smaller bubble diameter) were associated with faster degradation rates indicating the treatment efficiency was limited by the mass transport of PFAS to the plasma-liquid interface. Improvements in energy efficiency and removal rate were achieved by scaling from 2 to 25L and demonstrated viability for non-thermal plasma based techniques as a destruction technology for PFAS.