Mesoporous Adsorbents for Perfluorinated Compounds

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Effective adsorbents for polyfluorinated compounds (PFCs) were obtained and successfully tested in adsorption of perfluorooctanoic and perfluorooctanesulfonic acids. Bridged silsesquioxanes containing secondary and tertiary amino groups were synthesized by sol-gel condensation of bis[3-(trimethoxysilyl)propyl]amine and N-methyl-3,3′-bis(trimethoxysilyl)dipropylamine in acidic media in the presence of surfactants. Obtained materials were mesoporous with high BET surface area. They combine high structural stability with high concentration of surface amino groups serving as adsorption sites. Batch adsorption tests demonstrated their high adsorption capacity on PFCs: in some experiments it reached up to 88% of the adsorbent weight. Adsorption of PFCs changed the surfaces of the adsorbent nanoparticles from hydrophilic to hydrophobic thus providing their agglomeration and floatability. Column tests showed fast adsorption of PFCs even at high concentrations and high flow rates. Obtained results can be used in the development of an effective filtration device for clean-up of water contaminated by PFCs.