PNNL

Abstract

Nucleation and growth of bulk magnesite (MgCO3) is well known to be kinetically inhibited at room temperature due to strong hydration of Mg2+. In operando X-ray diffraction was used to follow the temperature dependence of forsterite carbonation to magnesite within the nanoconfined space of adsorbed H2O films ~2 nm thick (~10 monolayers) and determine an apparent activation energy of only 36±6 kJ/mol. This anomalously low value suggests that Mg2+ under nanoconfinement may adopt a hydration configuration that mimics that of aqueous Ca2+, at least energetically, if not also specifically in hydration structure.