Thin-film composite membrane formed by interfacial polymerization of polyvinylamine (PVAm) and trimesoyl chloride (TMC) for nanofiltration

This study focus on the preparation and nanofiltration properties of a novel thin-film composite polyamide membrane formed by the interfacial polymerization of polyvinylamine (PVAm) and trimesoyl chloride (TMC) on a porous polysulfone supporting membrane. The fabrication of the PVAm–TMC composite membrane was conducted by studying preparation parameters including reaction time, pH of the aqueous phase solution, reactant concentration, as well as curing temperature and time. The properties of the resultant membrane were characterized in terms of morphological structure, surface zeta potential, pure water flux, molecular weight cut-off (MWCO) and rejections to different solutes including electrolytes and organic dyes. The results showed that the optimized composite membrane had a smooth and amphoteric surface with an isoelectric point at pH about 6.5, a MWCO of around 650 Da, a pure water permeability of about 8.5 l/m2 h bar and good long-term stability. The rejection order of the membrane to inorganic salts changed from MgCl2 < NaCl < MgSO4 < Na2SO4 at pH of 7.0 to NaCl < Na2SO4 < MgSO4 < MgCl2 at pH of 6.0. The dye removal tests also indicated that the obtained membrane could effectively reject the negatively charged organic dyes at neutral pH with good anti-fouling property, especially for the dyes with relatively higher molecular weight and/or more negative charge.

► TFC membrane for nanofiltration can be prepared through interfacial polymerization of PVAm and TMC. ► The TFC membrane has a MWCO of 650 Da and a pure water permeability of 8.5 l/m2 h bar. ► The rejection order of the TFC membrane is MgCl2 < NaCl < MgSO4 < Na2SO4 at pH of 7.0. ► The rejection order of the TFC membrane is NaCl < Na2SO4 < MgSO4 < MgCl2 at pH of 6.0. ► The TFC membrane can effectively reject anionic dyes at neutral pH with good anti-fouling property.