A Fresh Molecular Look at Calcite-Brine Nanoconfined Interfaces

KIRCH, ALEXSANDRO; DE ALMEIDA, JAMES MORAES; SANCHEZ, VERONICA M.; MUTISYA, SYLVIA MUENI; MIRANDA, CAETANO RODRIGUES

JOURNAL OF PHYSICAL CHEMISTRY C

AMER CHEMICAL SOC

Lugar: Washington; Año: 2018

1932-7447

Calcite-fluid interface plays a central role in geochemical, synthetic and biological crystal growth. The ionic nature of calcite surface can modify the fluid-solid interaction, the fluid properties under spatial confinement and can also influence the adsorption of chemical species. We investigate the structure of solvent and ions (Na, Cl and Ca), at calcite-aqueous solution interface under confinement, and how such environment modify the water properties. To properly investigate the system, molecular dynamics simulations were employed to analyze the hydrogen bond network and to calculate NMR relaxation times. Here, we provide a new insight with additional atomistically detailed analysis by relating the topology of the hydrogen bond network with the dynamical properties in nanoconfinement interfaces. We have shown that the strong geometrical constrains and the presence of ions, do influence the hydrogen bond network, resulting in more extended geodesic paths. Hydrogen bond branches connect low to high dynamics molecules across the pore and hence may explain the glue-like mechanical properties observed in confinement environment. Moreover, we showed that the surface water observed at calcite interface is characterized by slow transversal spin relaxation time (T$_2$) and highly coordinated water molecules. The physical and electrostatic barrier emerged from the epitaxial ordering of water result in a particular ionic distribution which can prevent the direct adsorption of a variety of chemical species. The implications of our results delineate important contributions to the current understanding of crystallization and biomineralization processes.