Interfacial polymerization layer with CNT providing fast water channels under electric field for efficient desalination of nanofiltration membranes

Abstract

In order to solve the contradiction between permeability flux and selectivity in nanofiltration membrane desalination technology, a novel interfacial polymerization layer structure was designed. In this structure, the hydrophilic modified carbon nanotubes (CNT) untangled and protruded the PA layer under the electric field, resulting in the generation of microporous water channels between CNT and polyamide molecules. Thanks to this unique membrane surface structure, the permeability of the nanofiltration membrane was significantly enhanced, reaching 24.4 L·m−2·h−1·bar−1, in which the rejection of MgCl2 and Na2SO4 were also maintained at 96.1 % and 97.3 %, respectively. At the same time, the surface of the nanofiltration membrane remained intact in the chlorine resistance test, and the total fouling rate caused by lysozyme (LYZ) protein solution was only 2.89 %, demonstrating excellent chlorine resistance and pollution resistance. The design of changing surface structure through electric field-assisted nanomaterials provides a new innovative strategy for the development of separation membrane.