Preparation and characterization of 5-isocyanato-isophthaloyl chloride/ZnO/hyperbranched polyamide nanofiltration membranes

In order to obtain high-flux antifouling nanofiltration membrane, a series of ICIC/ZnO/HBPA nanofiltration membranes were prepared by interfacial polymerization of 5-isocyanato-isophthaloyl chloride (ICIC) and hyperbranched polyamide (HBPA) on the surface of polyacrylonitrile (PAN) ultrafiltration membrane, the nano-ZnO was incorporated into the polyamide separation layer. The existence of ZnO is confirmed by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The analysis results of water contact angle indicate that the membrane hydrophilicity is increased by incorporation of ZnO nanoparticles, the lowest water contact angle of the membrane is 22.7°. Compared with the membrane without ZnO, the flux and the salt rejection rate for NaCl, MgCl2, Na2SO4 and MgSO4 of the membrane containing ZnO increase. The largest flux of the ICIC/ZnO/HBPA membrane is about 102 L·m-2·h-1, which is nearly 2.6 times of the membrane without ZnO. The bacteriostasis of the membranes to E. coli is enhanced by incorporation more ZnO. Increasing the monomer content or prolonging the interfacial polymerization time is beneficial to increasing the salt rejection rate, but the order of the salt retention rate is changed. When HBPA is 0.8%, ICIC is 0.1%, content of ZnO is 0.02 g and reaction time is 10 min, the salt rejection rate for NaCl, MgCl2, Na2SO4 and MgSO4 of the prepared membrane are 60.8%, 96.4%, 95.1%, 96.7% and the flux is 53, 54.7, 53.7 L·m-2·h-1and 54.7 L·m-2·h-1, respectively.