虽然纳米多孔氧化石墨烯(GO)被认为是最有前途的反渗透脱盐膜之一,对通过大GO孔控制脱盐性能的关注有限,主要是由于显著的离子泄漏导致这些孔的次优性能。在这项研究中,我们采用分子动力学模拟方法来证明Mg2+离子,粘附于羧基化的GO纳米孔,可以充当门,调节离子(Na+和Cl-)通过多孔GO膜的传输。具体来说,纳米孔附近二价阳离子的存在降低了孔附近盐离子的浓度并延长了它们穿过孔的渗透时间。这随后导致盐截留率的显著提高。此外,离子截留率随着吸附的Mg2+离子的增加而增加。然而,吸附的Mg2离子的存在会损害水的运输。这里,我们还阐明了石墨烯氧化程度对脱盐的影响。此外,我们设计了吸附Mg2离子量和氧化度的最佳组合,以实现高的水通量和盐截留率。这项工作为开发用于受控水淡化的新型纳米多孔氧化石墨烯膜提供了有价值的见解。
While nanoporous graphene oxide (GO) is recognized as one of the most promising reverse osmosis desalination membranes, limited attention has been paid to controlling desalination performance through the large GO pores, primarily due to significant ion leakage resulting in the suboptimal performance of these pores. In this study, we employed a molecular dynamics simulation approach to demonstrate that Mg2+ ions, adhered to carboxylated GO nanopores, can function as gates, regulating the transport of ions (Na+ and Cl-) through the porous GO membrane. Specifically, the presence of divalent cations near a nanopore reduces the concentration of salt ions in the vicinity of the pore and prolongs their permeation time across the pore. This subsequently leads to a notable enhancement in salt rejection rates. Additionally, the ion rejection rate increases with more adsorbed Mg2+ ions. However, the presence of the adsorbed Mg2+ ions compromises water transport. Here, we also elucidate the impact of graphene oxidation degree on desalination. Furthermore, we design an optimal combination of adsorbed Mg2+ ion quantity and oxidation degree to achieve high water flux and salt rejection rates. This work provides valuable insights for developing new nanoporous graphene oxide membranes for controlled water desalination.