(402g) Control of Pore Sizes in Ordered Mesoporous Carbons for the Sorption of PFAS Chemicals

Granular activated carbon (GAC) adsorption is commonly used for the removal of per-and polyfluoroalkyl substances (PFAS) from water. Its low sorption capacity and selectivity for short chain PFAS, e.g., perfluorobutanoic acid (PFBA), however, undermine its broad applications, especially, in the presence of natural organic matter (NOM) and other competing water constituents. This study aims to determine controlling mechanisms for PFAS sorption on carbon materials by developing ordered mesoporous carbons (OMCs) with precisely controlled pore sizes. Ordered microporous and mesoporous carbons with increasing pore sizes from 0.8, 1.6, 3.0, 4.2 to 5.3 nm were synthesized by a hard template method using Pluronic P-123 surfactant and tetraethyl orthosilicate. The performance testing results showed that the smaller the pore size, the better the removal performance toward short chain and long chain PFAS. For 0.8 nm OMCs, the sorption ability of perfluorooctanoic acid (PFOA) and PFBA increased by 102.9% and 378.7%, respectively, when compared to that of 5.3 nm OMCs. The observed sorption ability toward PFBA here is higher than most of the reported adsorbents, approaching 64 umol/g. When the pore size of an OMC is ≤ 3 nm, no significant inhibition was observed in both PFOA and PFBA sorption tests in the presence of 5 ppm NOM (humic acid).