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

Abstract

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.

Characterization of a Model Bioreactive Membrane for the Simultaneous Separation and Hydrolysis of Lipopolysaccharides

“…Initially, the M0 membrane support presented a contact angle of 54 ± 3°. This measured angle is in agreement with previous angles reported in the literature for the PAN material. − Then, the angle slightly increased up to 57.9 ± 0.8° for the M1 membrane after deposition of the second polymer PS- b -P4VP. Thereafter, the measurement for the final E-TFC membrane revealed the lowest contact angle with an average of 33.7 ± 0.6°.…”

Zwitterionic and Photocatalytic Janus Membrane Based on Diethylamine N-Oxide Group and WS2 Nanosheets for Dye Removal in Forward Osmosis

“…6,7 Another important aspect in FO systems is the use of the osmotic pressure, where an osmotic gradient generated between a solution of higher water chemical potential (low osmotic pressure) to a solution of lower water chemical potential (higher osmotic pressure) drives the water molecules across the membrane, 8,9 and avoid the use of external mechanical pressure. 10 The architecture, selectivity, robustness, and reusability are critical regardless of the membrane-based separation process. The modification of the membrane's structural and chemical compositions is essential to achieve a highly functional membrane.…”

“…Among all the water purification methods, using membranes has become one of the most successful techniques to decrease or eliminate the high concentration of pollutants. Particularly, forward osmosis (FO) systems have demonstrated the ability to remove organic dyes because of the functionalization of the membranes to increase their hydrophilicity, avoiding the formation of fouling and rejecting contaminants, such as organic pollutants. , Another important aspect in FO systems is the use of the osmotic pressure, where an osmotic gradient generated between a solution of higher water chemical potential (low osmotic pressure) to a solution of lower water chemical potential (higher osmotic pressure) drives the water molecules across the membrane, , and avoid the use of external mechanical pressure …”

Graphene quantum dot doped viscoelastic lyotropic liquid crystal nanocolloids for antibacterial applications

“…These LLCs have many scientific and technological applications in display devices, drug delivery, water purification, printing, nanoparticle synthesis, and the medical and pharmaceutical industry. [6][7][8][9] In cosmetics (shampoo, soap, etc.) and pharmaceutical applications, the anionic surfactant-based LLC phases are mainly used for cleaning applications.…”