A robust underwater superoleophobic aminated polyacrylonitrile membrane embedded with CNTs-COOH for durable oil/water and dyes/oil emulsions separation

Considering the emulsified oil and water-soluble dyes in wastewater, the exploitation of easy-manufacturing, energy saving and high-efficiency separation materials is urgently required. In this work, integrating the positively charged polyethyleneimine (PEI) with negatively charged CNTs-COOH constructed the superhydrophilic Cassie-Baxter structure onto the electrospun polyacrylonitrile (PAN) membrane surface by ultrasonic, electrostatic interaction and thermal treatment. Based on it, the PEN@CNTs membrane achieved efficient separation for surfactant-free, tween 80-stabilized, SDS-stabilized, and CTAB-stabilized emulsions (the fluxes reached 508-3158 L m(-2) h(-1), the separation efficiency reached 99.42%) by the splendid water-penetration and oil-repellency, electrostatic interaction, and aperture sieve . Moreover, because of the porosity and strong charged surface of PEN@CNTs membrane, the anionic dyes can be quickly removed by one-step filtrate method (~403 L m(-2) h(-1)). Meanwhile, the PEN@CNTs membrane also achieved synchronous and efficient remediation for oil/dye mixture emulsions after many cycles. More importantly, facing the complex physical and chemical environments, the combination of the stabilized PEN membrane, inactive CNTs-COOH layer, and the bond of embedding method between CNTs-COOH and PEN nano fibers made the PEN@CNTs membrane demonstrated robust stability and durable separation capability.

Automated summary

In this study, a superhydrophilic Cassie-Baxter structure was constructed on the surface of electrospun polyacrylonitrile (PAN) membrane by integrating positively charged polyethyleneimine (PEI) with negatively charged CNTs-COOH. The PEN@CNTs membrane achieved efficient separation and removal of emulsified oil and water-soluble dyes, demonstrating robust stability and durable separation capability.