Polydopamine intimate contacted two-dimensional/two-dimensional ultrathin nylon basement membrane supported RGO/PDA/MXene composite material for oil-water separation and dye removal

Titanium carbide (MXene) sheet membranes have become attractive candidates in terms of solvent nanofiltration performance. Whereas, the low contaminant removal ability limited the practical application of MXene membranes in efficient separation. Here, the reduced graphene oxide (RGO)/polydopamine (PDA)/titanium carbide (MXene) composites were prepared by dopamine modification method. Then, the RGO/PDA/MXene composites were suction filtrated on a nylon membrane to construct the two-dimensional-two-dimensional (2D-2D) laminated composite membrane. The effects of MXene content on the surface hydrophilicity, dye retention and oil-water separation properties of the modified membrane were systematically studied. Among them, the RPM-8 membrane exhibited ultra-high separation effect (>96%) and excellent throughput (>200 L/m2·h) for Methylene Blue (MB), Methyl Orange (MO), Methyl Red (MR), Congo Red (CO) and Evans Blue (EB). At the same time, the modified membrane shows very high oil-water separation effect on the emulsion (>97%). In addition, long-term cycle experiments have also revealed the stability of RGO/PDA/MXene composite membranes. The above results further illustrated the importance of the regular straight rigid channels of the composite membrane in separation performance. Therefore, RGO/PDA/MXene composite membrane has tremendous potential in practical applications.