Lyotropic Liquid Crystal-Based Membranes for Water Remediation: Fabrication, Characterization and Performance Evaluation.

In water remediation, biomimetic membranes are gaining much attention due to their selectivity, dynamic stability, nontoxicity, and biocompatibility. Lyotropic liquid crystals (LLCs) are self-organizing networks that can conform to an array of geometries with high pore densities. As such, LLCs are excellent membrane materials for water applications because they are water insoluble and are manipulated to conform to an array of morphologies that provide natural water channels that are readily tunable in size. They have the ability to create uniform pores, between the range of 1 and 5 nm, with large surface areas. Thus, this work focuses on the design, fabrication, and characterization of LLC-modified Janus-type membranes for forward osmosis applications. Physical characterization of the membranes was performed using scanning electron microscopy (SEM), and the results show an open-pore radius and the presence of both finger- and sponge-like pores depending on membrane preparation. The contact angle assessment indicates that as the membranes are further modified with other polymers (e.g., PAN), higher hydrophilicity and surface energy are achieved. Moreover, the Brunauer-Emmett-Teller (BET) analysis showed a significant variation in the pore distribution between membranes. Functionalized membranes presented satisfactory water flux and superior salt rejection compared to nonfunctionalized membranes. SupPACMoDS membranes are 83% more efficient at preventing salt back flux than the nonmodified version. This is credited to the thickness and pore structure provided by the PAN support layer in the membrane.