Assessing total PFAS content via CIC and evaluating foam fractionation removal efficiency in wastewater

Details

Supervisors

Gerin, Patrick A.

Faculty

Faculté des bioingénieurs

Degree label

Master [120] : bioingénieur en sciences et technologies de l'environnement, à finalité spécialisée

Abstract

enPer- and polyfluoroalkyl substances (PFASs) have been widely used in industry since the 1940s due to their unique physicochemical properties, which has led to their global spread. These “forever chemicals” pose risks to human health and ecosystems, making their monitoring and removal from the environment a pressing challenge. However, the diversity, trace concentrations, and strong persistence of PFASs complicates both their detection and treatment. As a preliminary step for the later quantitative analysis of total PFAS by combustion-ion chromatography (CIC), this study explored the efficiency of the IC step, for fluoride and the sample preconcentration step to increase the sensitivity of the method to low PFASs concentrations. IC enabled the reliable detection of fluorides down to 1.6 ppbF, corresponding to a CIC limit of quantification of 96 ppbF. IC was also able to quantify the concentration of trifluoroacetate (TFA), the highly soluble and most volatile ultra-short-chain PFAS. Using TFA as a reference PFAS, we demonstrated the feasibility of concentrating the samples: evaporation achieved a concentration factor of 155 with complete retention of TFA; adsorption onto activated carbon reached a capacity of 671 µgTFA,adsorbed/gAC. Both approaches require further testing in complex matrices and with other PFASs. As a wastewater treatment technology, foam fractionation aided with a foaming additive demonstrated high removal efficiency for long-chain PFASs in low-turbidity water, but was less effective for short-chain substances and highly sensitive to suspended matters. Improving this process will require optimized additives and pretreatment systems to broaden its applicability. Overall, in preparation for CIC analysis of total PFAS, this work demonstrates the feasibility of the IC step, identifies promising sample concentration strategies validated with TFA, the most difficult ultra-short-chain PFAS. The work also underlines the potential, of foam fractionation for PFAS removal from wastewater. Further research should aim at integrating these methods into robust monitoring and treatment strategies to reduce PFAS emissions to the environment.