Carbon nanotubes as a scaffold in the Ti3C2Tx(MXene)-derivatized membrane for oil/water emulsion separation

Membrane separation has been widely used in the treatment of oily wastewater, but traditional membrane materials are easily polluted, and it is difficult to overcome the trade-off effects between water flux and retention rate. Recently, 2D MXene materials with adjustive microstructures and abundant surface functional groups have been used to fabricate functional composite membranes. In this work, the CNTs-TiO2-Ti3C2Tx composite materials were suction filtrated on a support (nylon membrane) to construct the laminated composite membrane. The layer spacing was controlled by adjusting the mass ratio of carbon nanotubes (CNTs), and the crosslinking reaction of polydopamine (PDA) and polyethyleneimine (PEI) was used to modify the membranes synergistically. The CNTs-TiO2-Ti3C2Tx (CTT) membrane had superhydrophilic and underwater superoleophobic characteristics as well as high efficiency in oil/water emulsion separation. CTT membranes exhibited a high separation effect ( > 99.9%) for various emulsified oils. Compared to the TiO2-Ti3C2Tx (TT) membrane (211.62 L m−2 h−2 bar−1), the pure water flux of the composite membrane (CTT-1) displayed high permeation flux over 4432.13 L m−2 h−2 bar−1. Moreover, the CTT membrane exhibits fouling resistance and stable water flux even after ten testing cycles. Therefore, CTT composite membranes with flexible layer spacing overcome the trade-off effects and have tremendous potential in practical applications.