Unique dual superlyophobic covalent organic frameworks (COF-TpBD) intercalated MXene composite membrane for efficient oil-water separation

Abstract

The development of composite membranes utilizing transition metal carbides and nitrides, exemplified by Ti3C2Tx (MXene), has proven efficacious in the treatment of oily wastewater. However, challenges arise from the prolonged and convoluted transport paths within MXene interlayer nanochannels, significantly impeding mass transfer and diminishing membrane permeability. This investigation incorporated porous covalent organic frameworks (COFs) as intercalating agents into two-dimensional (2D) MXene-based membranes to expand the interlayer nanochannels. The resulting MXene@COF-TpBD functional layer polyethersulfone (PES) composite membrane exhibited a distinctive dual superoleophobic surface, concurrently manifesting underwater superoleophobicity and underoil superhydrophobicity (underwater oil contact angle > 150°, underoil water contact angle > 150°). The membranes exhibited excellent water flux (up to 4092.7 L·m-2·h-1·bar-1), efficient oil-water emulsion separation (up to 1908.4 L·m-2·h-1·bar-1, rejection rates >99.78%), noteworthy fouling resistance and structural stability, outperforming most of existing similar membranes. Furthermore, supported by the extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory, the incorporation of COF-TpBD improved the antifouling characteristics of the composite membrane. This work presents innovative insights into the improvement of 2D MXene membranes and the use of COF-TpBD for the specific remediation of oily wastewater.