Positively-charged nanofiltration membrane constructed by polyethyleneimine/layered double hydroxide for Mg2+/Li+ separation

• Published in: Desalination Vol. 548; p. 116256
• Main Authors: Ni, Hongxu, Wang, Naixin, Yang, Yuye, Shen, Mengxin, An, Quan-Fu
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.02.2023
• Subjects: Layered double hydroxides; Mg2+/Li+ separation; Nanofiltration; Positively charged membrane; Positively charged membrane; Nanofiltration; Mg2+/Li+ separation; Layered double hydroxides
• ISSN: 0011-9164; 1873-4464
• DOI: 10.1016/j.desal.2022.116256

As an important resource, lithium is abundant in Salt Lake. The high Mg2+/Li+ ratio is the main obstacle to lithium extraction. Positively-charged nanofiltration membrane has shown great potential in the separation of Mg2+/Li+. Herein, we report a facile method to construct positively-charged nanofiltration membrane by polyethyleneimine (PEI) and layered double hydroxide (LDH) nanosheets on hydrolyzed polyacrylonitrile ultrafiltration membrane. Subsequently, the PEI-LDH composite membrane was crosslinked with glutaraldehyde (GA) to improve its stability. The incorporation of LDH could improve the positive charge of the membrane. Then, the obtained PEI-LDH/GA membrane showed an enhanced separation performance for separating Mg2+/Li+ in an aqueous solution. When the Mg2+/Li+ ratio was 10, the membrane showed a separation factor (SMg2+/Li+) of 18.7. Moreover, the membrane could maintain the separation performance for 100 h, which exhibited a potential application in Mg2+/Li+ separation. [Display omitted] •Mg2+/Li+ separation membrane was obtained with the incorporation of LDH.•The positively charge was enhanced to improve the separation factor.•The separation factor of Mg2+/Li+ was stable in 100 h.