Fabrication of a novel thin-film nanocomposite (TFN) membrane containing MCM-41 silica nanoparticles (NPs) for water purification

A thin-film nanocomposite (TFN) membrane containing porous MCM-41 silica nanoparticles (NPs) was prepared by the in situ interfacial polymerization (IP) process. Aqueous m-phenyl diamine (MPD) and organic trimesoyl chloride (TMC)-NPs mixture solutions were used in the IP process. Porous MCM-41 (∼100 nm) and non-porous spherical silica NPs (∼100 nm) were synthesized and used as the fillers to fabricate the TFN membrane at concentrations ranging from 0 to 0.1 wt%. The membranes were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM) and attenuated total reflection Fourier transform infrared (ATR FT-IR) spectroscopy, and their performances were evaluated based on the water permeability and salt rejection. Results indicated that the MCM-41 NPs dispersed well in polyamide (PA) thin-film layer and improved membrane performances under optimal concentrations. By increasing concentration of MCM-41 NPs, hydrophilicity, roughness and zeta potential of TFN membranes all increased. Notably, the permeate water flux increased from 28.5±1.0 to 46.6±1.1 L/m2 h with the incorporation of MCM-41 NPs, while maintaining high rejections of NaCl and Na2SO4 (97.9±0.3% and 98.5±0.2%, respectively). A comparison between the membranes with non-porous silica NPs (S-TFN) and with the porous MCM-41 NPs (M-TFN) suggested that the internal pores of MCM-41 NPs contributed significantly to the increase of water permeability.