Optimizing the preparation of multi-layered polyamide membrane via the addition of a co-solvent

Polyamide membranes with controlled surface morphology were prepared by the interfacial polymerization of 1,3-phenylenediamine (MPD) with 1,3,5-benzenetricarbonyl trichloride (TMC) on polysulfone ultrafiltration supports. The addition of co-solvents (acetone, ethyl acetate, and diethyl ether) into the organic phase was used to control both the surface morphology and the polyamide network structures. The as-prepared membranes had multi-layered polyamide structures, which consisted of large (1 μm) and ordinal (100–300 nm) ridge-and-valley formations. Permeate flux and rejection reactions were successfully controlled by the types and amounts of co-solvents that were added. The optimal membrane conditions included the addition of 3 wt% ethyl acetate, with a NaCl rejection of more than 99% and a permeate flux of more than 1.8 m3/(m2 d) at 1.5 MPa, which was more than three times higher than the membranes prepared without a co-solvent.