Abdulazeez Ismail, Salhi Billel, Baig Nadeem, Peng Qing
Interdisciplinary Research Center for Membranes and Water Security, King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi Arabia.
Physics Department, King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi Arabia.
Membranes (Basel). 2021 Nov 28;11(12):940. doi: 10.3390/membranes11120940.
Lithium-ion consumption has risen significantly in recent years due to its use in portable devices. Alternative sources of lithium, which include the recovery from brine using the sustainable and eco-friendly electrodialysis technology, has been explored. This technology, however, requires effective cation-exchange membranes that allow the selective permeation of lithium ions. In this study, we have investigated, via molecular dynamics simulations, the role of the two common charged groups, the sulfonic and the phosphoric groups, in promoting the adsorption of monovalent ions from brine comprising Li, Na, Mg, and Ca ions. The analysis of the mean square displacement of the ions revealed that Li and Na ions exhibit superior diffusion behaviors within the polyelectrolyte system. The O-atoms of the charged groups bind strongly with the divalent ions (Mg and Ca), which raises their diffusion energy barrier and consequently lowers their rate of permeation. In contrast, the monovalent ions exhibit weaker interactions, with Na being slightly above Li, enabling the permeation of Li ions. The present study demonstrates the role of both charged groups in cation-exchange membranes in promoting the diffusion of Li and Na ions, and could serve as a guide for the design of effective membranes for the recovery of these ions from brine.
近年来，由于锂离子在便携式设备中的应用，其消耗量显著增加。人们已经探索了锂的替代来源，其中包括使用可持续且环保的电渗析技术从卤水中回收锂。然而，这项技术需要有效的阳离子交换膜，以实现锂离子的选择性渗透。在本研究中，我们通过分子动力学模拟，研究了两种常见的带电基团——磺酸基和磷酸基，在促进包含锂、钠、镁和钙离子的卤水中单价离子吸附方面的作用。对离子的均方位移分析表明，锂和钠离子在聚电解质体系中表现出优异的扩散行为。带电基团的氧原子与二价离子（镁和钙）强烈结合，这提高了它们的扩散能垒，从而降低了它们的渗透速率。相比之下，单价离子表现出较弱的相互作用，钠略高于锂，这使得锂离子能够渗透。本研究证明了阳离子交换膜中带电基团在促进锂和钠离子扩散方面的作用，并可为设计从卤水中回收这些离子的有效膜提供指导。
