Performance improvement of thin film nanocomposite membranes by covalently bonding with Janus porous hollow nanoparticles for nanofiltration applications

Abstract

Incorporation of nanofillers into membranes is one of effective ways to improve the performance of membranes. Various nanofillers are induced into the polymeric matrices, including nonporous nanofillers, porous nanofillers, and hollow nanofillers. In this study, thin film nanocomposite (TFN) membranes covalently incorporated with Janus porous hollow nanoparticles with opposite surface charges are prepared by interfacial polymerization. The effects of the Janus porous hollow nanoparticles on performances of the composite membrane including surface hydrophilicity, surface charge, surface roughness, water permeability, salt rejection, and antifouling resistance are investigated. The incorporation of Janus porous hollow nanoparticles improves the overall performance of the membranes. The hydrophilicity and surface charge increase as the loading of nanoparticles increases, and the roughness increases firstly and then decreases. The flux of the TFN membranes (96.8 LÁh À1 Ám À2 at 0.5 MPa) has more than doubled compared with unmodified composite membranes, mainly due to the additional channel provided by hollow structure of nanoparticles with porous shells, accompanied with high level rejections (>97%) against Na 2 SO 4 and MgSO 4 . The NaCl rejection increases from 49.7% to 55.9% due to the synchronous rejection ability of cations and anions given by the dually charged composite nanoparticles. The chemically modified TFN membranes show improved stabilities in the pure water and the humic acid solution with decrements in flux about 2% and 6% respectively, due to the improved surface properties.