Surface engineering of graphene oxide membranes for selective separation of perfluorooctanoic acids.

Perfluoroalkyl compounds (PFCs) are environmental toxicants and their widespread detection and accumulation in the environment can be detrimental to the ecosystem. In this study, surface charge of GO membranes was engineered to enhance selectivity of graphene oxide (GO) membranes and for the removal of perfluorooctanoic acid (PFOA ∼400 Da) in real concentration ranges in wastewater streams. The structure and physicochemical properties of the GO and modified GO nanosheets and their corresponding membranes were assessed using several characterization techniques. The modified GO membranes showed a water flux of 83.1 ± 1 L m−2 h−1 together with maximum rejection efficiency of 98.4% for 50 ppm PFOA at pressure of 0.45 MPa, which is the highest value reported to date. Compared to the GO membrane, the modified GO membrane exhibited higher water flux and PFOA rejection efficiency by 300% and 70%, respectively. The high surface charged and electron rich GO nanosheets reduce the interlayer spacing in the modified membrane and simultaneously enhance the surface hydrophilicity which leads to increased PFOA retention and enhanced water permeation. These results point to the potential of the modified GO membranes for wastewater treatment. [Display omitted] • Surface of graphene oxide membrane was engineered by positive and negative chargers. • PDDA and PSS were used to, respectively, create positive and negative charges. • The modified membranes showed high increase in water-flux and PFOA rejection efficiency. • The obtained rejection efficiency for PFOA molecules by PDDA-GO membranes was 98.4%. [ABSTRACT FROM AUTHOR]