Efficient removal of perfluorooctanoic acid using fluorinated ionic liquids and granular activated carbon

Abstract

Perfluoroalkylated and polyfluoroalkylated substances (PFAS) are persistent and bioaccumulative compounds in the environment and the human body. Their presence in high concentrations brings devastating consequences to health. Nowadays, there is an urgent need to develop efficient and sustainable processes that mitigate the damage caused by PFAS to improve the life quality of individuals. In the present work, perfluorooctanoic acid (PFOA) extraction properties with fluorinated ionic liquids (FILs) in aqueous media were evaluated for the first time. The most promising FIL is [P44414] [C4F9SO3] obtaining uptake capacities up to 280 mg·g−1 in 72 h. To verify if this performance is competitive for the best materials used so far in the literature for PFAS removal, adsorption processes were carried out with granular activated carbon (GAC) obtaining adsorption capacities up to 666 mg·g−1 (best fitted with the pseudo-second-order kinetic model) with an equilibrium time of 48 h. Equilibrium assays showed maximum uptake capacities around 500 mg.g−1, and multilayer adsorption due to the best fit to the Freundlich model. Both materials (FILs and GAC1240W) can open new paths in PFAS removal processes from aqueous solutions. Taking advantage of the properties of each one of these compounds, new, more efficient, and sustainable processes can be optimised in the future.