Calculating PFAS interfacial adsorption as a function of salt concentration using model parameters determined from chemical structure

A fundamental model for calculating interfacial adsorption of complex ionic and nonionic PFAS mixtures in the presence of mixed salts

“…Calculations with divalent salts use α 2 = α 1 /2 (see ref. 15). bModel parameters for PFNA and PFDA were obtained from UNSW-OU model fits to no-added-salt surface tension data, with an assumed nominal α value of 0.7.cCalculated values based on chemical structure using the equations from ref.…”

“…bModel parameters for PFNA and PFDA were obtained from UNSW-OU model fits to no-added-salt surface tension data, with an assumed nominal α value of 0.7.cCalculated values based on chemical structure using the equations from ref. 15.dSDS parameters from fits in ref. 14 to original data from ref.…”

“…ref. 10, 14 and 15), following a similar derivation approach, but generalized for complex mixed systems. Note that this model is designed to be used for mixtures containing any combination of ionic and nonionic surfactant components, provided the mixture does not contain oppositely-charged surfactants ( i.e.…”

“…In previous work, the authors developed a model (the UNSW-OU salt model) to predict the impacts of inorganic salt concentration and composition on the air-water interfacial adsorption of ionic PFAS, and then extended the model to cases where mixed salts are present. 10,14,15 The original model was shown to be capable of predicting the interfacial activity of individual ionic PFAS components as a function of salt concentrations for a single salt type. 14 A modied version of the model was developed to allow predictions for systems of individual PFAS in the presence of multiple co-existing counterions of different valences.…”

“…10 Methods of determining parameters for any variation of the model based on PFAS chemical structure were described in ref. 15.…”