L-lysine functionalized Ti3C2Tx coated polyurethane sponge for high-throughput oil–water separation

Creating an efficient method that can provide simple, practical and high-throughput separation of oil–water mixtures has proved extremely challenging. Two-dimensional layered Ti 3 C 2 T x MXene material with excellent hydrophilicity has attracted substantial attention for oil–water separation. However, conventional Ti 3 C 2 T x separation membranes are susceptible to contamination by oil due to its relatively high adhesion to oil, hindering its practical applications in high-efficiency oil–water separation. To make Ti 3 C 2 T x have underwater superoleophobicity and low oil adhesion, the surface of Ti 3 C 2 T x can be modified by introducing hydrophilic groups. Herein, L-lysine functionalized Ti 3 C 2 T x (Ti 3 C 2 T x -Ly) was firstly prepared by decorating L-lysine on Ti 3 C 2 T x through electrostatic interaction and hydrogen bonding. A facile dip-coating method is then used to coat polyurethane (PU) sponge with Ti 3 C 2 T x -Ly, obtaining a superhydrophilic/underwater superoleophobic Ti 3 C 2 T x -Ly @PU sponge. Owing to the excellent underwater superoleophobicity resulting from hydrophilic groups (–OH、–NH 3 ) on the surface of Ti 3 C 2 T x -Ly nanosheets and the enlarged interlayer spacing of Ti 3 C 2 T x , the Ti 3 C 2 T x -Ly @PU sponges demonstrated outstanding separation performance for a series of oil–water mixtures. Specifically, the Ti 3 C 2 T x -Ly @PU sponge exhibits low oil adhesion and superhydrophilic (WCA = 0°)/submerged superoleophobic (UOCA > 155°) properties. The Ti 3 C 2 T x -Ly @PU sponges displayed the best separation performance for cyclohexane/water mixture, and the maximum permeation flux is up to 221892 L m –2 h –1 , accompanied by a remarkable separation efficiency of higher than 99.2% after 100 cycles. The permeation flux has exceeded most of the previous reported multifunctional separation membranes. In addition, the Ti 3 C 2 T x -Ly @PU sponge also showed excellent separation performance for high-density oil dichloromethane/water with a separation efficiency over 99.4%. Of note, the Ti 3 C 2 Tx-Ly @PU sponge features excellent chemical stability to corrosive media, such as acidic, alkaline, and high salt solutions, possessing great potential for real-world applications. Furthermore, the as-prepared Ti 3 C 2 T x -Ly @PU sponge exhibits rapid and efficient separation of oil-water mixtures through a fully gravity-driven process, which makes it a good candidate for industrial oil-contaminated water treatment and oil spill clean-up, and also provides new insights into the design and development of functional Ti 3 C 2 T x through L-lysine modification. Therefore, this work reports a facile and promising way to fabricate scalable superhydrophilic/underwater superoleophobic sponge material for highly efficient oil–water separation. • Super-hydrophilic and super-oleophobic Ti 3 C 2 T x -Ly @PU sponge was prepared. • Ti 3 C 2 T x -Ly @PU sponge exhibits an excellent oil–water separation performance. • Ti 3 C 2 T x -Ly @PU sponge shows stable water flux and impressive oil pollution resistance. • Ti 3 C 2 Tx-Ly @PU sponge features excellent chemical stability to corrosive media.