Dissolution Anisotropy of Pyroxenes: Role of Edges and Corners Inferred from Stochastic Simulations of Enstatite Dissolution - CNRS - Centre national de la recherche scientifique Accéder directement au contenu
Article Dans Une Revue Journal of Physical Chemistry C Année : 2021

Dissolution Anisotropy of Pyroxenes: Role of Edges and Corners Inferred from Stochastic Simulations of Enstatite Dissolution

Arnaud Bouissonnié
Philippe Ackerer

Résumé

Experimental studies exhibit a wide variety of dissolution rates for a given mineral depending on the chemical conditions and also on the type of experiment conducted. As a relevant example, studies focused on face-specific dissolution and those focused on powder dissolution can present differences of up to 1 order of magnitude. Linking these two types of experiments is therefore relevant, since experimental conditions can be almost entirely controlled throughout the entire experiment. In this study, we use a stochastic dissolution model based on hydrolysis of atomic bonds of enstatite, the magnesium endmember pyroxene, to simulate the dissolution of different sizes and aspect ratios of enstatite grains. This model, validated in a previous study by a comparison with experimental (face-specific) rate data, is used to understand the evolution of the dissolution rate with time, from the beginning of the dissolution until the entire consumption of the crystal. We show that the behavior of the dissolution is controlled mainly by the aspect ratio of the grain. A simple dissolution model based on face-specific dissolution is then used to compare the results of the simulations obtained with those resulting from the grain dissolution model. The similarity between the results points out that the contribution to the dissolution of edges and corners is only modest for very anisotropic silicates such as pyroxenes, where silicate tetrahedrons are connected through chains running parallel to a given crystallographic axis. This simple model is then extended using both face-specific experimental and model results and compared to existing powder dissolution results. This comparison shows an excellent agreement between face-specific dissolution modeling and powder dissolution experiment, indicating that, for anisotropic minerals such as pyroxenes, face-specific and powder dissolution experiments can be linked, which can be of great interest for future dissolution studies.
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Dates et versions

hal-03389765 , version 1 (22-10-2021)

Identifiants

Citer

Arnaud Bouissonnié, Damien Daval, Philippe Ackerer. Dissolution Anisotropy of Pyroxenes: Role of Edges and Corners Inferred from Stochastic Simulations of Enstatite Dissolution. Journal of Physical Chemistry C, 2021, 125 (14), pp.7658-7674. ⟨10.1021/acs.jpcc.0c11416⟩. ⟨hal-03389765⟩
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