Anti‐swelling polyethyleneimine‐modified MXene nanofiltration membranes for efficient and selective molecular separation

• Published in: EcoMat (Beijing, China) China), 2023-03, Vol.5 (3), p.n/a
• Main Authors: Xing, Chao, Zhang, Yuting, Huang, Rong, Li, Suhong, He, Jing, Fu, Rong, Lai, Chao, Liu, Changyu, Shen, Lingdi, Zhang, Shanqing
• Format: Article
• Language: English
• Subjects: Acid dyes; Cold; Contact angle; d‐spacing; Interlayers; Mechanical properties; Membranes; Morphology; MXene; MXenes; Nanofiltration; nanofiltration membrane; Nanotechnology; Permeability; Polyacrylonitrile; Polyethyleneimine; purification; Rejection rate; Scanning electron microscopy; Spectrum analysis; Substrates; Swelling; Two dimensional materials; two‐dimensional
• ISSN: 2567-3173; 2567-3173
• DOI: 10.1002/eom2.12300

Two‐dimensional (2D) MXene‐based nanofiltration membranes could sustainably and rapidly produce clean water. However, the challenges related to the severe swelling of the MXene membranes in water should be overcome before the practical application. In this work, the negatively charged MXene‐based membrane is modified by positively charged polyethyleneimine (PEI) with various PEI:MXene ratios. The PEI‐MXene is deposited on a polyacrylonitrile (PAN) substrate as a top membrane to prepare an anti‐swelling composite PEI‐MXene/PAN membranes with outstanding mechanical strength and stability. Interestingly, when the interlayer spacing of the top Mxene layers are tuned between ca. 14.15 and ca. 14.52 Å, the resultant PEI‐MXene/PAN membranes exhibit the excellent ability of size sieving. For instance, PEI‐MXene(1:1)/PAN membrane presents high flux performance to Acid Blue 90 (AB90), Congo Red (CR), and Direct Red 80 (DR80) (i.e., 563.9, 882.6, and 633.6 L m−2 h−1, respectively) at 0.2 MPa, and remarkable rejection rates, that is, 99.3%, 99.82%, and 99.9%, respectively. Besides, the PEI‐MXene(0.5:1)/PAN possesses the highest flux of 1528.1 L m−2 h−1 and outstanding rejection rate of 99.9% to dye of AB8GX. Moreover, the proposed strategy can be extended to the modification of other 2D material nanofiltration membranes. A series of anti‐swelling PEI‐MXene/PAN composite membranes were designed and fabricated for nanofiltration. The d‐spacing of the PEI‐MXene layer could be tuned to various values in the range from 14.15 to 14.52 Å at various PEI:MXene ratios for selective separation to various dyes of different sizes. In addition, the resultant membranes have a long‐life span and outstanding stability.