An efficient strategy for the preparation of MIL-53(Al)-NH_(2)membranes with high ion selectivity and desalination performance

一种制备具有高离子选择性和脱盐性能的MIL-53(Al)-NH_(2)膜的有效策略

The efficient extraction of sodium(Na^(+))and lithium(Li^(+))from seawater and salt lakes is increasingly demanding due to their great application value in chemical industries.However,coexisting cations such as divalent calcium(Ca^(2+))and magnesium(Mg^(2+))ions are at the subnanometer scale in diameter,similar to target monovalent ions,making ion separation a great challenge.Here,we propose a simple and fast secondary growth method for the preparation of MIL-53(Al)-NH_(2)membranes on the surface of anodic aluminum oxide.Such membranes contain angstrom-scale(~7Å)channels for the entrance of small monovalent ions and water molecules,endowing the selectivities for monovalent cations over divalent cations and water over salt molecules.The resulting high-connectivity MIL-53(Al)-NH_(2)membranes exhibit excellent ion separation performance(a selectivity of 121.42 for Na^(+)/Ca^(2+)and 93.81 for Li^(+)/Mg^(2+))and desalination performance(a water/salt selectivity of up to 5196).This work highlights metal–organic framework membranes as potential candidates for realizing ion separation and desalination in liquid treatment.

钠(Na^(+))和锂(Li^(+))在化学工业中具有巨大的应用价值,因此对从海水和盐湖中高效提取钠和锂的技术要求越来越高。然而,二价钙离子(Ca^(2+))和镁离子(Mg^(2+))等共存阳离子的直径与目标单价离子的直径均处于亚纳米级尺寸,这使得分离目标离子成为一项巨大的挑战。本文提出了一种简单快速的二次生长方法,在阳极氧化铝表面制备MIL-53(Al)-NH_(2)膜。该膜含有埃级(约~7Å)通道,允许较小的一价离子和水分子进入,从而调节一价阳离子对二价阳离子的选择性和脱盐性能。所制备的MIL-53(Al)-NH_(2)膜具有出色的离子分离性能(Na^(+)/Ca^(2+)选择性为121.42,Li^(+)/Mg^(2+)选择性为93.81)和脱盐性能(水/盐选择性高达5196)。这项工作表明MOF膜在离子分离和脱盐的应用中极具潜力。