Construction of well-confined sub-nanochannels for molecular-sieving in organic solvent environment remains a challenge for organic solvent nanofiltration (OSN) membranes in precise fluid separation. Herein, cyclodextrin (CD) cross-linked 2D Ti 3 C 2 T x MXene membranes with laminar nanostructure containing unique sub-nanoscale mass transfer channels for unprecedented OSN performance is reported. Density-functional theory (DFT) calculation and experimental results confirm that CD monomers (α-, β-, γ-) with 3D intrinsic cavity structures are anchored with Ti 3 C 2 T x MXene nanosheets forming a stable polyester cross-linking network via an interfacial molecular engineering using trimesoyl chloride (TMC). The prepared membranes exhibit ultrahigh OSN performance with excellent stability in organic solvents. The optimal membrane can effectively reject dyes such as methylene blue (99.8%), rhodamine B (98.0%), and Congo Red (100%), while having high ethanol permeability ranging from 22.58 to 85.31 L/(m 2 h bar). Remarkably, the membrane structure remained intact after 4 weeks immersion in ethanol and acetone. This work provides a facile and reliable strategy to construct a high-performance 2D material-based OSN membrane with well-confined mass transfer channels.
Huan Qin,Haoyu Wu,Shu-Mao Zeng,Fan Yi,Si-Yong Qin,Yue Sun,Li Ding,Haihui Wang
Osmotic energy is a kind of blue energy that has recently been identified as an additional source of clean energy. Using a membrane-based reverse electrodialysis (RED) process, this blue energy can be obtained from acidic industrial wastewater with different proton concentration gradients. However, this process demands high-performance membrane that can withstand harsh environments, possessing the advantages of wide pH tolerance, high-temperature resistance and chemical stability, developing such membranes remain a challenge. Herein, we report a two-dimensional (2D) lamellar Ti 3 C 2 T x MXene membrane-based RED device for osmotic energy capturing from proton gradients. Such a membrane exhibits a typical surface-charge-governed ion transport feature. Moreover, the MXene membrane-based energy harvesting device holds the merits of outstanding pH and temperature resistance. It exhibits an output power density of 6.5 W/m 2 and also demonstrates stability over 200 h at pH = 0, which is 30% higher than the commercialization benchmark (5 W/m 2 ). The osmotic power density can be further enhanced to 11.1 W/m 2 at 330 K, demonstrating excellent thermal and chemical stability. This work can help better understand protons' transport behaviors in MXene membranes and open new avenues for applications in sustainable power conversion and wastewater treatment.
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