Improving the performance of RO membrane fabricated on highly porous support membrane with porous organic polymer fillers

Abstract

Previously, seawater desalination technology has developed due to intensifying water shortages due to climate change, continuous environmental pollution, and a surge in population. Therefore, many studies are being conducted to solve the trade-off problem, which is an obstacle to improving performance. In this study, the porous polymer was synthesized using 4,4'-bis(chloromethyl)-1,1'-biphenyl (BCMBP) and triphenylamine (TPA) through a Friedel-Crafts alkylation reaction. In addition, a sulfonation reaction was conducted to increase hydrophilicity. Thus, we made four types of fillers. The synthesized porous polymers were introduced into the selective layer of the RO membrane and acted as a water transport channel that can only pass water through the pores. Additionally, the support was modified to obtain high flux. The support was fabricated with 10wt% of polymer and a co-solvent system of dimethylformamide(DMF), and n-methylpyrrolidone(NMP). It has highly narrow, straight and uniform pores. A RO membrane was fabricated with 0.005 wt% of fillers on the highly porous support. The RO membrane fabricated on the highly porous support membrane with the most hydrophilic filler due to amine and sulfonation reaction showed high water permeability of 4.3 LMH/bar while maintaining the high salt rejection because of the synergistic effects of the support membrane and fillers.