Mesoporous hollow nanospheres with amino groups for reverse osmosis membranes with enhanced permeability

Aiming at enhancing the permeability of reverse osmosis (RO) membranes, polyaniline-co-polypyrrole hollow mesoporous nanospheres (PPHMNs) were synthesized with aniline and pyrrole monomers via a simple and rapid one-step method, and then added to the aqueous phase of interfacial polymerization to fabricate thin-film nanocomposite (TFN) membranes. Hollow cores of the PPHMNs embedded in polyamide layers could reduce the interior transfer resistance of the membrane and shorten the transmission pathway of water molecules. Mesoporous shell of PPHMNs provided more channels for rapid transmission of water molecules. Moreover, amino groups in PPHMNs originated from the monomer of aniline could not only be bonded to polyamide (PA) layer by reacting with acyl chloride groups to prevent the leakage but also improve hydrophilicity of the membrane. Water flux of TFN membrane doped with PPHMNs (TFN-Ps) of 0.005 wt% addition concentration was 34.1 L·m−2·h−1 which is 76.7% higher than that of thin-film composite (TFC) membrane, and the NaCl rejection all kept over 99.0%. The TFN-Ps also showed excellent long-term stability, chlorine resistance and anti-fouling performance. This work opens an avenue for application of mesoporous hollow nanospheres with amino groups synthesized by simple and time-saving methods in developing TFN membranes with improved water flux.