Facile Preparation of an Asymmetric Wettability Janus Cellulose Membrane for Switchable Emulsions’ Separation and Antibacterial Property

Abstract

Effective emulsions’ separation is greatly significant for human health and environmental remediation. In this work, a Janus cellulose membrane (JCM) with asymmetric wettability and strong antibacterial activity was successfully fabricated by facile in situ immobilization and single side modification method. During the typical preparation process, Ag nanoparticles were first immobilized on the CM surface, and then one side of the CM was protected using adhesive tape for subsequent hydrophobic modification. The obtained JCM possessed superhydrophobic property on one side, whereas the other side was superhydrophilic. More importantly, the JCM exhibited excellent separation performance for various oil-in-water and water-in-oil emulsions without external energy and the separation efficiency was more than 96.0%. Meanwhile, the separation efficiency and flux had no dramatic fluctuations after 10 separation cycles, indicating fabulous separation recyclability of the JCM. In addition, both sides of the JCM exhibited strong antibacterial activity against Escherichia coli and Staphylococcus aureus, and the antibacterial phenomenon was attributed to the intrinsic antibacterial capability of Ag nanoparticles on the hydrophilic side and the noncontact effect of the hydrophobic side. The facile preparation process and exceptional separation performance of the JCM will provide more enlightenment for the design and preparation of Janus separation materials for potential industrial applications.

Asymmetric Cellulosic Membranes: Current and Future Aspects

“…The common treatment methods for industrial wastewater have a process that is complicated, not cost-effective, and can produce subordinate pollution, as well as showing an in-vain effect for emulsions of droplets with smaller diameters (<20 µm). Importantly, it is not uncommon that this treatment has difficulty in demonstrating the demulsification phenomenon under natural conditions and complications [20].…”

“…As a case in point, a super-hydrophilic/oleophobic polyvinylidene fluoride membrane fabricated thorough an in-situ crosslinking copolymerization approach showed good efficiency on separation and superlative recyclability performance for oil-in-water emulsions. Hence, specific membrane materials that can ascertain the switchable separation for both oil-in-water and water-in-oil emulsions are most desirable [20].…”

“…The JCM demonstrated amazing recyclability, while the efficiency and flux showed minimal variations over ten cycles of separation. The JCM can be further developed for the productions of separation material for possible commercialization with industrial strategies [20]. Meanwhile, ZnO/MnO 2 hybrid CAM for effective separations was recently reported, which has an inclusion of anisotropic wettability, effective separations, cost-efficiency, and environmentally friendly features.…”

“…However, the application of cellulosic materials is restricted by its surface chemistry and bacterial degradation. Therefore, its wettability, together with antibacterial features, are appreciable assets for the separation of industrial wastewater [20].…”

“…A specific CAM with wettability and other functions was fabricated, and the functionalized CAM demonstrated antibacterial/antimicrobial properties suitable for practical environments [20].…”