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

Abstract

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.

Nanofiltration Membranes with Crumpled Polyamide Films: A Critical Review on Mechanisms, Performances, and Environmental Applications

“…Specifically, nodular, , stripe, ,, and ring ,− structures are the three most common morphologies (Figure ). Other structures, such as fishnetlike and octopus-sucker-like structures, are occasionally represented in some studies (Figure S1 provides the SEM images of some examples). Among these morphologies, only the nodular structure is observed in existing commercial membranes, and other morphologies mostly exist in custom-fabricated membranes in literature papers.…”

Employing Visible Light To Construct Photoinitiated Polymerized Nanofiltration Membranes for High Permeation and Environmental Micropollutant Removal

“…Water permeability ( A ) and solute permeability ( B ) of the salt solutions were ascertained to appraise the water/salt selectivity ( A/B ), and the trade-off effect between A/B and A is analyzed in Figure c. Breaking the trade-off effect suggests the notably promoted NF performance . Neither the membrane merely irradiated by light nor the membrane with the single addition of AMPS broke the trade-off effect.…”

“…PP and IP processes were integrated to prepare a light-mediated polymerizable NF membrane. The traditional NF membrane called the pristine membrane was built similarly to the procedure in our previous work . Detailed procedures about photopolymerized membranes are provided in Section S2 (Figure S2).…”

“…Breaking the trade-off effect suggests the notably promoted NF performance. 23 Neither the membrane merely irradiated by light nor the membrane with the single addition of AMPS broke the trade-off effect. Membrane A + I managed improved A and R, which signified the breakthrough of the trade-off relationship with A/B and A values of 25.84, 30.26, and 0.82, 31.47 for Na 2 SO 4 and NaCl solutions, respectively, surpassing the other membranes.…”

Capacitance-Tuning Guides the Electric Antifouling Membrane Design

“…Membrane fouling is a particular concern for membrane-based water purification. − This usually leads to a significant decline of membrane permeability and limits its economic performance. Traditional strategies for membrane fouling control, such as chemical cleaning and backwashing, , generally suffer from high chemical/energy consumption and secondary pollution. , Electrochemical antifouling, a chemical-free technology, has been considered as a promising alternative strategy in recent years. Significant progress has been made in mitigating the fouling of organic, inorganic, and biological substances during ultrafiltration (UF). ,, Membrane fouling can be relieved by directly applying an additional potential − to the membrane, introducing electrostatic repulsion of the negatively charged foulants. − However, antifouling performance enhancement is still a challenge for viable applications.…”