(541b) A Novel Hydrophilic Nanofiltration Membrane with Excellent Performance

A hydrophilic thin-film-composite (TFC) nanofiltration (NF) membrane with high flux and dual resistance to fouling and chlorine has been designed and synthesized through the interfacial polymerization (IP) of amino-functional polyethylene glycol (PEG) and trimesoyl chloride, which can be utilized for antibiotics separation. The higher hydrophilicity alongside the larger pore size of the PEG-based selective layer is the key to a high water flux of 66.0 L m^-2 h^-1 at 5.0 bar. With mean pore radius of 0.42 nm and narrow pore size distribution, the MgSO₄ rejections of the PEG based PA TFC NF membranes can reach up to 80.2 %. The hydrophilic PEG based membranes shows positive charged since the isoelectric points range from pH=8.9 to pH=9.1 and the rejection rates for different salts of the novel membranes are in the order of R(MgCl₂)>R(MgSO₄)>R(NaCl)>R(Na₂SO₄). The pore sizes and water permeability of these membranes are tailored by varying the molecular weight and molecular architecture of amino-functional PEG. Due to the unique structure of the selective layer of the PEG based membranes consisting of saturated aliphatic construction unit (CH₂-CH₂-O), the membranes demonstrate dual resistance to fouling and chlorine. The membranes maintain good salt rejections and high water flux of PEG based membranes after treatment by 2000 ppm NaClO for 24 hours.  Interestingly, the PEG based membranes exhibit excellent fouling resistance with a water flux recovery of 90.2 % using BSA as a model molecule.  More importantly, the hydrophilic PEG based NF membranes have been exploited to separate several water soluble antibiotics (such as tobramycin, an aminoglycoside antibiotic applied in the treatment of various types of bacterial infections), showing excellent performance in concentration or removal of antibioics.  By optimizing operating conditions, the advanced membranes show highly stable tobramycin solution flux of 37 L m^-2 h^-1 alongside tobramycin rejections up to 96 % with 50 ppm feed concentration under 8.0 bar.  When the feed concentration increases up to 800 ppm, our membranes can still exhibit a high rejection over 92 %. Therefore, as a promising “green”  technique capably declining the solvent emissions and energy-consuming, the designed PEG based NF membranes owning highly efficient antibiotic concentration ability together with dual resistance to fouling and chlorine have great potentials in substituting conventional separation techniques for concentration and purification of active molecules in pharmaceutical and fine chemicals industries.