Polyoxometalate based thin film nanocomposite forward osmosis membrane: Superhydrophilic, anti-fouling, and high water permeable

Abstract

Thin-film composite (TFC) membranes with high water flux and low reverse salt flux are the most conventional materials for forward osmosis (FO) process. However, these membranes are not suitable for natural or wastewaters treatment due to the intrinsic physicochemical and surface properties of the rejection layer. The present work shows the fabrication of new thin film nanocomposite (TFN) forward osmosis membranes incorporate superhydrophilic modified silica nanoparticles. Surface of silica nanoparticles were functionalized by quaternary ammonium groups and subsequently were coated using superhydrophilic wheel polyoxometalates (POM). TFN membranes containing different weight ratio of nanoparticles in PA rejection layer were synthesized by interfacial polymerization (IP) of m-phenylenediamine (MPD) and trimesoyl chloride (TMC) as monomers in aqueous and organic solution, respectively. POM coated silica nanoparticles were dispersed in aqueous solution of MPD monomer prior to IP process. The changing in the performance and physicochemical properties of TFN membranes incorporating with superhydrophilic nanoparticles were investigated by different instrumental analysis and were compared with a pristine TFC membrane. Compared to pristine TFC membrane, the TFN membrane with 0.2 wt% nanoparticle incorporation (TFNw0.2) showed superior water flux (18 vs. 31 LMH in FO mode) and negligible increases in reverse salt flux (6.25 vs. 8.45 gMH). In addition, better anti-fouling propensity toward protein (bovine serum albumin, BSA) and organic (sodium alginate, SA) foulant was observed. Therefore, Using newly developed thin film nanocomposite membranes may provide a novel class of high-performance membrane for FO processes.