Computational exploration of the anion exchange on the basal surface of layered double hydroxides by molecular dynamics

SR Tavares and JFS Haddad and PIR Moraes and AA Leitao, APPLIED SURFACE SCIENCE, 513, 145743 (2020).

DOI: 10.1016/j.apsusc.2020.145743

The anion exchange between the adsorbed anions on the basal surface of Mg2Al-layered double hydroxide and a guest anion (OH-) was monitored by means of molecular dynamics. A bottom-up strategy was adopted in order to investigate this phenomenon. First, the structural features of the exfoliated forms in vacuum were analyzed. The distribution of the water molecules and anions (NO3-, Br- and CO32-) on the Mg2Al layer could be elucidated. Afterwards, the size of the simulation systems was increased by bringing the exfoliated structures into contact with liquid water and by stacking adjacent Mg2Al layers. The comparison between the dispersion of adsorbed anions throughout the liquid water indicated a strong affinity between CO32-/Mg2Al layer. Furthermore, no anion exchange between CO32- and the guest OH- was detected, suggesting that the hydroxyl anions only approach the available adsorption sites on the surface.

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