Fabrication of 2D/2D composite membrane via combining functionalized MXene and MoS2 nanosheets for dye/salt separation

MXene nanosheets were functionalized by introducing sodium lignosulfonate (LS) containing abundant hydrophilic groups (sulfonic acid groups and phenolic hydroxyl groups), along with the intercalation of MoS 2 nanosheets between the functionalized MXene layers. A pressure-assisted self-assembly was utilized for the fabrication of a two-dimensional (2D) MXene membrane with high water permeation and excellent dye separation characteristics. The MoS 2 @LS-MXene composite membrane has excellent pure water flux (188.1 L·m -2 ·h -1 ), which is 85% higher than that of the unfunctionalized MXene membrane, and has a good rejection effect on dye molecules (93% for Congo red (CR), and 99% for Rhodamine B (RhB)). The appropriate interlayer spacing and negative surface charge resulted low rejection of salts (4.2% of NaCl, 4.6% of Na 2 SO 4 ) in dye-salt hybrid system, consequently leading to their mutual separation. The composite membrane also exhibits excellent stability and anti-fouling ability. This study provides a simple and novel design idea for the preparation of high-performance 2D MXene membrane.