Capture of Perfluorooctanoic Acid using Oil-Filled Graphene Oxide-Silica Hybrid Capsules

Author(s): Zhenjie Liu, Shane P Meaney, Luke W Giles, Phillip Holt, Mainak Majumder and Rico F Tabor

Fluorinated hydrocarbon (FHC) contamination has attracted global attention recently, due to persistence within the environment and ecosystems of many types of FHC. The surfactant perfluorooctanic acid (PFOA) is particularly commonly found in contaminated sites, and thus needs urgent action to be removed from the environment. In this study, water dispersible hybrid capsules were successfully prepared from an oil-in-water emulsion stabilized by grapheme oxide and including a silicate precursor, to grow a strong and mesoporous capsule shell surrounding the droplets. These capsules were decorated with amine groups to present a positively charged outer corona that attracts negative PFOA molecules. The aminated capsules were effectively applied as a novel technology to adsorb and sequester PFOA contamination in water. It was confirmed that PFOA removal by the capsules was pH and PFOA concentration dependent, with adsorption efficiencies of >60 mg g−1 in ideal conditions. PFOA removal kinetics followed using HPLC and LCMS showed that capture of PFOA by the capsules reached a maximum of >99.9% in 2–3 days.