Foaming Properties of per- and Polyfluoroalkyl Substances (PFAS) for Remediation Purposes

Per- and polyfluoroalkyl substances (PFAS) are a collection of over 6,000 manmade substances, which exhibit high chemical and thermal stability. PFAS are surface-active compounds due to a hydrophobic, fluorinated tail and a hydrophilic head group. Given their unique chemical properties, PFAS have been commonly used in several consumer products, including aqueous film-forming foams (AFFFs), nonstick coatings, packaging, and cleaners. As a result of their broad applications, PFAS have leeched through the air-water interface into natural reservoirs including water sources. In addition, long-chain PFAS, those with more than seven carbons in the fluorinated chain, tend to accumulate the human body. Consequently, there have been substantial concerns as PFAS are carcinogenic and have adverse impacts on human and environmental health. Therefore, addressing the presence of PFAS molecules in water resources is a serious concern. Remediation using solid surfaces for adsorption, such as activated carbon and ion exchange resins, may remove PFAS contaminants, but regenerating the adsorbent and removing the surface-active PFAS involves complex and expensive difficulties. Remediation using gas injection, like in foam flotation, can address these setbacks by making the PFAS adsorbate more accessible downstream. However, current foam floatation processes are not viable for PFAS removal. Critically, the present project shapes a framework for foamability of PFAS systems, establishing foaming evolution diagrams based upon PFAS length, aeration period, air flowrate, and ionic strength. Evaluation of the foam stability (FS) and foaming capacity (FC) are analyzed through dynamic foaming volume, mean bubble area (MBA), bubble count (BC), and liquid content (LC).