Abstract
Foam fractionation offers a promising solution for the separation of surface-active contaminants from water. Therefore, this work aims to comprehensively investigate foaming behavior and its correlations with the interfacial properties. As a case study, we evaluate foaming of per- and polyfluoroalkyl substances (PFAS), which are one of significant environmental issues worldwide due their pervasive presence in the environment. Since there is no universal model to describe the foaming behavior of surfactants that can be applied to PFAS, this research utilizes dimensional analysis to establish a correlation between the foaming behavior of PFAS solutions—characterized by expansion rate of foaming—and dimensionless numbers that represent both processing and interfacial characteristics. Foaming parameters, such as gas flow rate and aeration time, are varied to study their effect on PFAS foamability. In addition, we study PFAS with different headgroups and with different chain lengths in the presence of electrolytes with different concentrations. Our study elucidates distinct, condition-specific equations for individual PFAS, revealing that long-chain PFAS foaming is significantly influenced by interfacial property-related dimensionless numbers, such as the Boussinesq number. Additionally, the Froude number and Weber number affect the foamability of both long- and short-chain PFAS. Moreover, our study identifies specific trends, including a maximum foaming capacity at a certain Capillary number, aligning with the maximum in dilatational interfacial modulus. The results suggest more studies are needed on bubble interaction and foam film behavior.
Original language | English |
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Journal | Soft Matter |
DOIs | |
State | Accepted/In press - 2024 |
Externally published | Yes |
Funding
The Bureau of Reclamation (BoR) provided financial support for this work under the Grant of R21AC10418-00. The authors also thank the Institute for Applied Surfactant Research (IASR) for providing instruments used in this work.
Funders | Funder number |
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Bureau of Reclamation | R21AC10418-00 |
Bureau of Reclamation |