Inhibiting the concentration polarization of FO membranes based on the wettable microporous supporting layer and the enhanced dense skin layer

A novel thin film composite‐type forward osmosis (FO) membrane with inhibited concentration polarization phenomenon and expectant separation performance was prepared by continuous interfacial polymerization method. The nylon‐6,6 microfiltration membrane with the average pore size of 5 μm and the self‐wetting property was for the first time used as the supporting layer of the FO membranes, which decreased the mass transfer resistance in the porous supporting layer. The skin layer was prepared via the continuous interfacial polymerization of polyamide as a relatively dense layer, with the reverse salt flux of less than 1 g/m−2 h−1. The mass transfer resistance and the reverse salt flux of the prepared FO membranes were remarkably reduced due to the functional design of the double‐layer structure, which effectively enhanced the separation selectivity and restrain the concentration polarization of the FO membranes.