Mercury exchange in zeolites Na-A and Na-Y studied by classical molecular dynamics simulations and ion exchange experiments
Mercury exchange in zeolites Na-A and Na-Y studied by classical molecular dynamics simulations and ion exchange experiments
复制标题
DOI：
10.1016/j.micromeso.2021.110903
复制
发表时间：
2021-01-28
影响因子：
5.2
通讯作者：
de Leeuw, Nora H.
中科院分区：
文献类型：
--
作者：
Hernandez-Tamargo, Carlos;Kwakye-Awuah, Bright;de Leeuw, Nora H.
采用经典分子动力学模拟研究了在330 ~ 360 K的干燥和水合条件下，Si/Al比为1的Na- a分子筛和Si/Al比为2和5的Na- y分子筛中Na+与Hg2+的交换，以了解沸石对水净化性能的影响因素。建立了基于DFT能量的Hg2+离子与沸石O原子相互作用的经典力场。在水扩散方面，沸石Na-A的计算扩散率最低，其次是沸石Na-Y （Si/Al=2）和Na-Y (Si/Al=5)，这是由于孔隙尺寸和框架外离子负载不同造成的。在没有形态形成阴离子的情况下，Hg2+离子在LTA和FAU框架类型的超笼窗口上都被一致地吸附。沸石A的孔径减小，每Hg2+离子的平均水化数为
Classical molecular dynamics simulations have been employed to study the exchange of Na+ for Hg2+ in zeolite Na-A, with a Si/Al ratio of 1, and zeolite Na-Y, with Si/Al ratios of 2 and 5, in dry and hydrated conditions within the temperature range 330 - 360 K, to understand factors underpinning the performance of zeolites for water decontamination. A classical forcefield based on DFT energies has been developed for the interaction between the Hg2+ ions and the zeolite O atoms. In terms of water diffusion, zeolite Na-A shows the lowest calculated diffusivity, followed by zeolite Na-Y (Si/Al=2) and Na-Y (Si/Al=5), as a consequence of differing pore dimensions and extra-framework ion loadings. In the absence of speciation anions, the Hg2+ ions are consistently adsorbed at the supercage windows in both the LTA and FAU framework types. The reduced pore size of zeolite A leads to an average hydration number per Hg2+ ion of