Constructing CNTs-based composite membranes for oil/water emulsion separation via radiation-induced “grafting to” strategy

Abstract

Radiation-induced “grafting to” method was reported for the first time to modify multiwalled carbon nanotubes (MWNTs) with good solution processibility through covalently grafting polyvinyl alcohol (PVA) onto MWNTs’ side walls under γ-ray irradiation at room temperature. FT-IR, 1H NMR, XPS, TEM, Raman and TG results demonstrated that PVA chains were successfully grafted onto MWNTs, which exhibited excellent dispersibility and stability in aqueous solution. Furthermore, CNTs-based composite membranes were facilely constructed by depositing the modified MWNTs on cellulose acetate (CA) microporous membranes with the assistance of vacuum, which showed great hydrophilicity and underwater superoleophobicity. The obtained composite membranes were used to separate dodecane-in-water emulsions through a cross-flow mode, and exhibited high filtration flux (∼1660 L m−2 h−1 bar−1) and oil-rejection (>99.1%). Moreover, high water flux recovery (>86.5%) and almost constant filtration flux were also obtained after five cycles filtration of engine oil-in-water emulsion through the obtained composite membranes, while the bare CA membrane was completely fouled without any flux. This work shows a facile and effective solution process to modify nanocarbon materials and construct functional carbon-based membranes for diverse applications.