UTFacultiesTNWResearchDept CEPCFNewsThursday March 23, 11.30 hrs, Zuidhorst ZH 286, Colloquium Assistant Prof. dr. Helen King from Utrecht University.

Thursday March 23, 11.30 hrs, Zuidhorst ZH 286, Colloquium Assistant Prof. dr. Helen King from Utrecht University.

TITLE: Feedbacks influencing the reactivity of crystals at their interfaces with aqueous solutions

Crystal formation, growth and dissolution are predicted based on the bulk properties of the solid and aqueous fluids, which are used to estimate the distance of a system from thermodynamic equilibrium. Yet in reality, crystal reactivity and formation occur at and are dictated by the properties and chemical feedbacks that occur at the interface between aqueous solutions and crystalline solids. Over my career I have been examining how the chemistry of solutions can affect the reactivity of crystal surfaces using atomic force microscopy. This includes examining the reacting surfaces of magnesium carbonate materials, the main target in CO2 sequestration schemes using olivine, which I will discuss here. In many systems, the chemical feedbacks occurring at the reacting interface are so closely coupled in space and time that they produce pseudomorphs of the original crystal indicating that a very thin aqueous fluid layer is responsible for these reactions. I will present a review of different solid to solid phase transformations and examine the evidence that they are fluid-mediated as well as the influence of evolving solution chemistry in these systems. Again, this will be an important component for the longevity of CO2 sequestration schemes using olivine as the Mg-carbonates are known initially precipitate as metastable forms. Thus, I will also present why understanding the effect of chemistry during phase transformations of crystalline solids, particularly in the Mg-carbonate system, is also critical to understand the reactivity of these materials.