Ultralong MnO2 Nanowire Enhanced Multiwall Carbon Nanotube Hybrid Membrane with Underwater Superoleophobicity for Efficient Oil-in-Water Emulsions Separation

Carbon nanotube-based membranes with special wettability are ideal candidates to handle oily wastewater. However, their applications are limited owing to the low film-forming ability, unsatisfactory mechanical stability, and insufficient reusability. Herein, this work presents an effective strategy for fabricating a flexible multiwall carbon nanotubes (MWCNTs)/ultralong MnO2 nanowires (UL-MnO2-NWs) hybrid membrane, as well as its application in emulsion separation. In this strategy, the dispersed carbon nanotubes were obtained by acid treatment of agglomerate MWCNTs, and the UL-MnO2-NWs were prepared by a hydrothermal route. Then, the MWCNTs/UL-MnO2-NWs hybrid membrane with an improved mechanical property and excellent reusability was fabricated via vacuum-filtration of MWCNTs and UL-MnO2 -NWs suspension. The obtained hybrid membrane shows superhydrophilicity with a water contact angle of 0 degrees and underwater superoleophobicity with an oil contact angle of 152 degrees. It can effectively separate both surfactant-free and surfactant-stabilized oil-in-water emulsions with permeances up to 4900 L m(-2 )h(-1 )bar(-1) and high separation efficiency of greater than 99.7%. More importantly, the asprepared sample shows superior recyclability, antifouling property, and excellent mechanical and chemical stability, which match well with the requirements for treating the real emulsions. As a result, this hybrid membrane can be a potential candidate for practical application in water-in-oil emulsion separation.