Deciphering the role of polyketone substrates in tuning the structure and properties of polyamide nanofiltration membranes

Recent studies have emphasized the importance of porous substrates in the formation of a polyamide layer during the interfacial polymerization process. However, few studies have focused on the underlying effect of the porous support substrate on the structure and properties of the prepared polyamide nanofiltration (NF) membrane. In this study, various polyketone (PK) porous substrate supported NF membranes were successfully fabricated and optimized by tuning the pore structure and surface roughness of the PK substrate layer. Structural optimization was achieved by changing only the PK casting solution concentration during nonsolvent-induced phase separation without additional modification steps. The results demonstrated that the prepared hydrophilic fibrous PK membrane was conducive for the rapid and even diffusion of amine monomers and was an ideal substrate for NF membranes. Compared to the PK-16-supported NF membrane, a polyamide film with a more ridge-shaped nanostrip structure was easily formed on the PK-8 substrate with a large pore size and rougher surface, which greatly improved the permeance of the resultant NF membrane with a slight loss in salt rejection. Each PK substrate-supported NF membrane showed competitive separation performance compared to that of several reported membranes. This study highlights the superiority of PK porous membranes and provides a simple strategy for NF membrane production and water treatment applications.