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 MoS2 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 MoS2 @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 Na2SO4) 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.

Automated summary

In this study, MXene nanosheets were functionalized with sodium lignosulfonate (LS) and MoS2 nanosheets were intercalated between the functionalized MXene layers to fabricate a two-dimensional MXene membrane. This composite membrane exhibited high water permeation and excellent dye separation characteristics. It had a significantly higher pure water flux compared to the unfunctionalized MXene membrane and showed good rejection of dye molecules. The composite membrane also demonstrated low rejection of salts, leading to the mutual separation of dyes and salts. Additionally, the membrane displayed excellent stability and anti-fouling ability.