Nanofiltration Membranes with Octopus Arm-Sucker Surface Morphology: Filtration Performance and Mechanism Investigation

Precisely tailoring the surface morphology characteristics of the active layers based on bionic inspirations can improve the performance of thin-film composite (TFC) membranes. The remarkable water adsorption and capture abilities of octopus tentacles inspired the construction of a novel TFC nanofiltration (NF) membrane with octopus arm-sucker morphology using carbon nanotubes (CNTs) and beta-cyclodextrin (β-CD) during interfacial polymerization (IP). The surface morphology, chemical elements, water contact angle (WCA), interfacial free energy (ΔG), electronegativity, and pore size of the membranes were systematically investigated. The optimal membrane exhibited an enhanced water permeance of 22.6 L·m-2·h-1·bar-1, 180% better than that of the TFC-control membrane. In addition, the optimal membrane showed improved single salt rejections and monovalent/divalent ion selectivity and can break the trade-off effect. The antiscaling performance and stability of the membranes were further explored. The construction mechanism of the octopus arm-sucker structure was excavated, in which CNTs and β-CD acted as arm skeletons and suckers, respectively. Furthermore, the customization of the membrane surface and performance was achieved through tuning the individual effects of the arm skeletons and suckers. This study highlights the noteworthy potential of the design and construction of the surface morphology of high-performance NF membranes for environmental application.