Kinetic model of PFAS removal by semi-batch foam fractionation and validation by experimental data for K-PFOS

Adsorptive bubble separation techniques such as foam fractionation have recently been applied for the extraction of per- and polyfluoroalkyl substances (PFAS) from waters at both laboratory and operational scales. However, few authors have developed mathematical models of their removal of PFAS. This study presents a theoretical framework for the kinetics of PFAS removal from fresh and monovalent saline waters by a semi-batch foam fractionation process, by the mechanisms of adsorption, entrainment and volatilization, as a function of pertinent parameters including PFAS air-water adsorption, bubble radius, electrolyte concentration and ionic strength, PFAS volatility, and flow and geometric parameters. The freshwater model is validated for the removal of potassium perfluorooctane sulfonate (K-PFOS) using published experimental data (Meng, P. et al., Chemosphere, 2018, 203, 263–270). The proposed models provide quantitative tools for process design and the optimization of individual PFAS removal by semi-batch adsorptive bubble separation techniques such as foam fractionation. [Display omitted] •Previous models of PFAS removal by foam fractionation are limited to low PFAS concentrations.•Mathematical models are developed for PFAS removal by foam fractionation and other adsorptive bubble separation techniques.•The models include PFAS removal by adsorption, entrainment and volatilization mechanisms, in the first model allowing for a monovalent background electrolyte.•The formulation is validated for K-PFOS using previously published experimental data.