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

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.