Polypiperazine-amide nanofiltration membrane containing silica nanoparticles prepared by interfacial polymerization

Silica/polypiperazine-amide nanofiltration (NF) membranes were prepared by interfacial polymerization on polyethersulfone (PES) supporting membrane. Different preparation conditions and NF membrane performances were discussed, including silica concentrations, monomer concentrations, reaction time and salt rejections. The chemical structure characterizations of polyamide composite membrane were carried out by attenuated total reflectance infrared (ATR-IR). The surface images and cross sections were observed by scanning electron microscope (SEM) and atomic force microscopy (AFM). The results showed that polypiperazine-amide NF membrane prepared under the optimum conditions exhibited Na2SO4 rejection of 97.4% and water flux of 46.8 l.m− 2.h− 1. After addition of silica sol in the aqueous phase, the rejection of the resulting membrane changed slightly, but the water flux increased 21.1% than polypiperazine-amide NF membrane. According to the rejection of polyethylene glycols (PEGs), the molecular weight cut-off (MWCO) of the resulting membrane was under 600 Da.

► Silica sol is used for preparation of silica/polypiperazine-amide NF membrane. ► Different polymerization conditions on membrane performance were investigated. ► The water flux rate was higher than that of polypiperazine-amide NF membrane.