Zwitterionic functionalized MoS2 nanosheets for a novel composite membrane with effective salt/dye separation performance

Abstract

Polyethersulfone (PES) has been widely used as an ultrafiltration (UF) or nanofiltration (NF) membrane material in multiple industrial fields. But PES is hydrophobic in nature and easily contaminated. Thus, it is necessary to modify the PES membrane surface by physical or chemical methods for improving its hydrophilicity and other function. Herein, MoS2 modified by zwitterionic 2-methacryloyloxy ethyl dimethyl (3-sulfopropyl)-ammonium hydroxide sulfobetaine methacrylate (MoS2-PSBMA) was synthesized with a reverse atom transfer radical polymerization method (RATRP) and used to prepare MoS2-PSBMA/PES composite membranes via conventional phase inversion. The effect of MoS2-PSBMA content on the structure and properties was investigated by SEM, FT-IR, AFM and contact angle measurements. It was found that the hydrophilicity of the composite membrane increased with the content of zwitterionic functionalized MoS2nanosheets. Moreover, the composite membranes possessed a higher water flux (108.3 L m−2 h−1 at 0.6 MPa) and dye retention, 98.2% for Reactive Black 5% and 99.3% for Reactive Green 19. However, the rejection of Na2SO4, MgCl2 NaCl and MgSO4 was low, i.e., 2.2%, 1.2%, 1.1% and 0.3%, respectively. In summary, the synthesized composite membrane exhibited high selectivity for dye/inorganic salts and had a large potential for dye waste water treatment.