Direct deposition of two-dimensional MXene nanosheets on commercially available filter for fast and efficient dye removal.

Generally, the efficiency of water purification can be greatly increased by a high-flux membrane separation technology. One major challenge in the application of this technology is to achieve high removal efficacy of target pollutants with elevated water flux. Here we report a novel self-assembled composite by depositing two-dimensional MXene nanosheets on a commercialized mixed cellulose ester filter (as designated as MCM). Morphology study reveals that MCM exhibits an ultrathin flaked structure with uniform nanochannels which is stapled on a porous support. The tailored membrane has been successfully applied in the methylene blue solution treatment and 100% ± 0.1% removal rate is achieved while the feed concentration of dye solution is up to 90 mg·L-1. Concurrently, stable and comparatively elevated water flux was achieved, i.e., 28.94 ± 0.74 L·m-2·h-1, which is 1.88-fold of that of the commercialized UTC60 membrane. Further investigations on the separation mechanism are performed to get more insights into separation performance exhibited by MCM. It is found that the size-selective sieving, electrostatic repulsion of MXene and the high porosity of substrate play the synergistic effect on the fast and efficient dye removal behavior. Taken together, the composite membrane fabricated in present work provides an alternatively high-efficiency approach for dye treatment, and unflagging efforts will be further invested on the development and large-scale application of MXene-based membrane.