Gao Yi, Le Song-Thao, Kibbey Tohren C G, Glamore William, O'Carroll Denis M
School of Civil and Environmental Engineering, Water Research Centre, University of New South Wales, Sydney, NSW 2052, Australia.
School of Civil Engineering and Environmental Science, University of Oklahoma, Norman, OK 73019, USA.
Environ Sci Process Impacts. 2023 Nov 15;25(11):1830-1838. doi: 10.1039/d2em00466f.
Per- and polyfluoroalkyl substances (PFAS) are emerging contaminants that have been used extensively as firefighting agents and in a wide range of commercial applications around the world. As many of the most-common PFAS components are surfactants, they readily accumulate at interfaces, a process that can govern their environmental fate. There are thousands of PFAS compounds, and they have nearly always been used as mixtures, so it is common to find many different PFAS components present together in the environment. Furthermore, the interfacial behavior of ionic PFAS can be strongly influenced by the presence of salts, with adsorption dependent on both the composition and concentration of salts present. Any predictions of PFAS interfacial behavior made without considering both the mixed nature of PFAS present, as well as the composition of the salts present, have the potential to be off by orders of magnitude. To date, models capable of making predictions of PFAS interfacial adsorption when both mixed PFAS and mixed salts are present have not been presented. The work described here addresses this need by extending a mass-action model developed previously by the authors to allow predictions in cases where complex combinations of mixed PFAS and mixed salts are present. Predictions of PFAS interfacial affinity for a range of PFAS mixture conditions and ionic strengths are verified using experimentally-measured surface tension data. The new model provides physically-realistic prediction of interfacial adsorption of a wide range of PFAS mixtures over a wide range of salt concentrations and compositions. The model is capable of predicting interfacial adsorption of ionic/nonionic PFAS mixtures in the presence of salts, and can also make predictions when there is competitive adsorption between different PFAS components, a common case in PFAS source zones where high concentrations of multiple components are present and in foam fractionation reactors.
全氟和多氟烷基物质（PFAS）是新出现的污染物，在全球范围内被广泛用作灭火剂以及用于多种商业应用。由于许多最常见的PFAS成分是表面活性剂，它们很容易在界面处积累，这一过程会决定它们在环境中的归宿。PFAS化合物有数千种，而且它们几乎一直被用作混合物，因此在环境中常常会同时发现许多不同的PFAS成分。此外，离子型PFAS的界面行为会受到盐的强烈影响，吸附作用取决于所存在盐的组成和浓度。在不考虑所存在PFAS的混合性质以及所存在盐的组成的情况下对PFAS界面行为进行的任何预测，都有可能出现数量级的偏差。迄今为止，尚未提出能够在同时存在混合PFAS和混合盐的情况下对PFAS界面吸附进行预测的模型。本文所述工作通过扩展作者先前开发的质量作用模型来满足这一需求，以便在存在混合PFAS和混合盐的复杂组合的情况下进行预测。利用实验测量的表面张力数据验证了在一系列PFAS混合条件和离子强度下PFAS界面亲和力的预测结果。新模型对广泛盐浓度和组成范围内的多种PFAS混合物的界面吸附提供了符合物理实际的预测。该模型能够预测在有盐存在的情况下离子型/非离子型PFAS混合物的界面吸附，并且在不同PFAS成分之间存在竞争性吸附时也能进行预测，这在PFAS源区是常见情况，那里存在高浓度的多种成分，在泡沫分离反应器中也是如此。
