Preparation and characterization of low-pressure and high MgSO4 rejection thin-film composite NF membranes via interfacial polymerization process

Abstract

Low-pressure nanofiltration membrane produced by FILMTEC-DOW is generally considered by membrane industries as the commercial standard; according to its specification, for a 2000 ppm MgSO4(aq) feed, it yields 98.2% MgSO4 rejection and 22 GFD permeate flow at 70 psi applied cross-flow filtration pressure. Here we want to report our nanofiltration membrane development works on improved reactant formulation and fabrication process to produce our nanofiltration membrane having 98.2% MgSO4 rejection and 33 GFD permeate flow for the similar test conditions as FILMTEC-DOW did. Our near 50% improvement on water permeate flux over FILMTEC-DOW low-pressure nanofiltration membrane was due to the fact that an adduct salt named TEACSA was added to the aqueous piperazine aqueous solution during our membrane fabrication process. Besides evaluating the nanofiltration performances of our NF membranes, characterizations of the polyetherimide (PEI) microporous supports fabricated in our laboratory in the areas of pure water permeate fluxes at 40 psi cross-flow filtration pressure, wet–dry studies of hydrophobic porous polyetherimide and polysulfone supports, AFM and SEM were performed.