Green Layer‐by‐Layer Method for the Preparation of Polyacrylonitrile‐Supported Zinc Benzene‐1,4‐dicarboxylic Acid Membranes

Abstract

Ultrafiltration-level polyacrylonitrile (PAN) flat sheet membranes were chemically modified via cross-linking and hydrolysis to provide a suitable surface for the growth of a selective layer composed of Zn-benzene-1,4-dicarboxylic acid (Zn(BDC)) metalorganic framework (MOF). Unlike typical membrane modification methods or conventional MOF synthesis procedures, deionized (DI) water was the only solvent used for each of the modification steps involved. To better understand the layer-by-layer MOF growth, several MOF growth conditions were also studied, including the effects of solution concentration, growth temperature, membrane immersion time and the number of layers. Subsequently, organic solvent nanofiltration (OSN) was used as a means of testing the effectiveness of the modifications and comparing the performances of the fabricated membranes. With a proper combination of MOF growth conditions, the layer-by-layer method was able to produce an OSN membrane with an isopropanol (IPA) permeance of 2.39 L m-2 h-1 bar-1 and an 86% rejection of the dye Brilliant Blue R (Mw 825.97 g mol-1).