Designing Hydrogel-Modified Cellulose Triacetate Membranes with High Flux and Solute Selectivity for Forward Osmosis

Abstract

Forward osmosis (FO) has attracted intensive attention in liquid separation because it is less energy-consuming as compared to the pressure-driven separation processes, but the lack of a highperformance membrane limits its application. In this paper, novel FO membranes were fabricated by generating three methacrylate-based hydrogels (methyl-, ethyl-, and butyl-methacrylate) on the CTA surface via the solution drop-casting method. The characterization results show that the hydrogels were chemically crosslinked with the porous CTA substrate and improved the hydrophilicity of membranes. As a result, all the hydrogel-modified CTA membranes showed a higher pure water flux than the bare CTA and commercial HTI-CTA membranes. The modified FO membranes also exhibited higher solute selectivity and salt retention, as the hydrogels acted as the active barrier. In addition, antibacterial study demonstrated that hydrogel modifications conferred antibacterial properties to the CTA membranes, which is indicative of a better antifouling feature. The outstanding separation performance indicates that the hydrogel-modified CTA membranes have great potential for the industrial application.

Advances in Membrane Separation for Biomaterial Dewatering

“…In the literature, three major types of HCMs can be distinguished (Scheme ). In the most common geometry a hydrogel coating on a functioning membrane acts as an active layer. ,,,,,− In this geometry, the hydrogel functions as a selective separation layer ,, or as an antifouling coating. ,, Pore-filled membranes − are porous membranes filled with a hydrogel material. The hydrogel typically acts as a component that enables tuning the separation efficiency via external stimuli such as pH ,, and temperature. , …”

“…For each of the HCM geometries, a certain set of fabrication methods has been used (see Scheme ). Active layers were typically fabricated through casting, ,,,, electrospinning, spin coating, concentration–polarization, interfacial polymerization (IP), ,,, photografting, or NIPS. ,, On the other hand, pore-filled membranes have been prepared by track etching, ,, or by immersion in precursor solution, followed by polymerization through UV irradiation ,,, or heat . Lastly, draw solutes can be made by hydrogel bulk synthesis procedures, such as radical polymerization ,,, or emulsion polymerization .…”

“…In the most common geometry a hydrogel coating on a functioning membrane acts as an active layer. 24 , 25 , 179 , 199 , 201 , 212 − 231 In this geometry, the hydrogel functions as a selective separation layer 212 , 213 , 217 or as an antifouling coating. 179 , 219 , 222 Pore-filled membranes 232 − 238 are porous membranes filled with a hydrogel material.…”