摘要
用2,5-二(2-甲氧基-乙氧基)对苯二甲酰肼(BMTH)和1,3,5-三甲氧基-2,4,6-三甲酰基苯(TpOMe)缩聚,基于界面聚合法,在多孔三氧化二铝(AAO)基底上制备出一种二维共价有机骨架(COF)膜TpOMe-BMTH,并研究了所得膜材料对锂、镁离子的分离性能.结果显示,TpOMe-BMTH/AAO膜具有高的结晶性和良好的稳定性,并表现出优异的金属离子选择性,在LiCl(0.1 mol·L-1)和MgCl2(0.1mol·L-1)组成的二元混合离子体系中,对Li+/Mg2+的分离因子高达258.基于密度泛函理论的平面波赝势方法计算表明,材料孔道中的富氧低聚醚链对Li+和Mg2+的结合能分别为-282.69和-13.46 kJ·mol-1,使材料表现出强的亲锂特性,促进了 Li+沿着COF膜的一维孔道进行吸附扩散,最终实现锂、镁离子的高效分离.
Abstract
The two-dimensional covalent organic framework(COF)membrane material TpOMe-BMTH was prepared on the anodic aluminum oxide(AAO)substrate with 2,5-di-(2-methoxy-methoxy-ethoxy)-phenylmethylhydrazide(BMTH)and 2,4,6-trimethoxy-1,3,5-benzenetricarbaldehyde(TpOMe)condensation based on interfacial polymeriza-tion.The separation properties of the obtained membrane material for lithium and magnesium ions were investigat-ed.Results showed that the TpOMe-BMTH/AAO membranes possessed high crystallization,good stability,and excellent metal ion selectivity,with a separation factor of up to 258 for Li+/Mg2+in a binary salt system consisting of LiCI(0.1 mol·L-1)and MgCl2(0.1 mol·L-1).The plane wave pseudopotential method calculation based on the densi-ty functional theory showed that the binding energy of the oxygen-rich oligoether chains in the material pore for Li+and Mg2+was-282.69 or-13.46 kJ·mol-1.This result means that the obtained membrane has stronger lithium-philic properties and promotes Li+adsorption diffusion along the one-dimensional pore of the COF membrane,finally enabling the efficient separation of lithium and magnesium ions.
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