High-flux thin film nanocomposite forward osmosis membrane incorporated with blue lemon polyoxometalate based open-framework

Abstract

In this study a novel type of polyoxometalate based open-frameworks (POM-OFs) by using blue lemon (BL) as POM and tetrabutylammonium bromide (TBAB) as organic cationic coordinating agent successfully synthesized (BL.TBA-OFs) and incorporated in polyamide active layer via interfacial polymerization (IP) to fabricate hydrophilic and high water permeable thin-film nanocomposite (TFN) membranes. The prepared POM-OFs and TFN membranes were fully characterized using physicochemical techniques and the effect of POM-OFs incorporation on TFN membranes performance was investigated using reverse osmosis (RO) and forward osmosis (FO) experiments with regard to the water permeability, salt rejection, and selectivity. The enhancement in hydrophilicity of TFN membranes was confirmed by contact angle measurements, which attributed to the presence of superhydrophilic BL.POM. Water flux of the TFN-BL.TBA-4 membrane (with 400 ppm BL.TBA-OFs incorporation) increased from 18.1 to 28.6 LMH in FO mode, and 23.1 to 36.3 LMH in PRO mode, in comparison with unmodified TFC membrane. Enhancement in separation performance of the modified TFN membranes was attributed to the incorporation of nanopores BL.POM, which create short water pathways. By using sodium alginate as a foulant model the novel modified membrane showed better anti-fouling propensity than the TFC one. This report opens up a new modification route in the achieving of high efficient TFN membranes for FO process.