Effects of Surface Functional Groups and Porous Structures on Adsorption and Recovery of Perfluorinated Compounds by Inorganic Porous Silicas

The effects of porous structures and surface functional groups (silanol, 3-aminopropyltriethoxy, 3-mercaptopropyltrimethoxy, n-octyldichloroethoxy, and titanium substitution) on perfluorinated compounds (PFCs) adsorption and recovery were evaluated. The adsorption of PFCs on all adsorbents followed the pseudo-second-order model, and the adsorption rate was controlled by the pore diffusion, except for microporous zeofites and powder activated carbon (PAC). 3-aminopropyltriethoxy-grafted surface produced the highest PFCs adsorption capacities. Perfluorooctane sulfonic acid (PFOS) recovery from silica-based adsorbents (by ethanol extraction) efficiencies were higher than those of PAC and approached 100%. Hydrophobic organic functional groups can protect mesoporous structure from hydrolysis reactions in adsorption and solvent recovery processes. Supplemental materials are available for this article. Go to the publisher's online edition of Separation Science & Technology to view the free supplemental file.