Fluorinated thin-film composite membranes for nonpolar organic solvent nanofiltration

Polyamide (PA) is highly effective as a selective layer in case of nanofiltration (NF) membranes, mainly for filtering water and other polar solvents. The incorporation of fluorinated monomers in a polyamide network is a novel strategy for obtaining membranes with enhanced permeability in case of nonpolar solvents. In this study, PA thin-film composite membranes were prepared by interfacially reacting trimesoyl chloride (TMC) and 4,4ʹ-(hexafluoroisopropylidene)bis(benzoyl chloride) (HFBC) in an organic phase with 5-trifluoromethyl-1,3-phenylenediamine (TFMPD) in an aqueous phase in a single step. The resulting membrane obtained using HFBC exhibited a considerably increased nonpolar solvent flux and selectivity in the nanofiltration range. Thus, the hydrophobicity of the PA layer and its permeance are effectively enhanced because of the incorporation of the fluorinated monomer. Therefore, high-performance membranes can be obtained for nonpolar solvent separation in petroleum refineries and purification in the pharmaceutical industry.