Dissolution and Growth of (10(1) over-bar4) Calcite in Flowing Water: Estimation of Back Reaction Rates via Kinetic Monte Carlo Simulations

Journal Article · Sun Feb 15 00:00:00 EST 2004 · Journal of Crystal Growth

DOI:https://doi.org/10.1016/j.jcrysgro.2003.10.015· OSTI ID:15006480

Williford, Rick E; Baer, Donald R; Amonette, James E; Lea, Alan S

Although calcite is an important mineral for many processes, there have been relatively few simulations of it's growth and dissolution behavior. Such simulations are complicated by the multitude of defect types and by the asymmetry of the crystal. The present work combined a kinetic Monte Carlo (KMC) technique with the Kossel crystal (100) simple cubic concept and the Blasius boundary layer model to simulate the simultaneous growth and dissolution of the (1014)calcite cleavage surface in flowing water. The objective was to determine the activation energies of the back reaction (growth) from those of the forward reaction (dissolution) by obtaining agreement with cleavage-step morphologies and step dissolution velocities previously measured using an atomic force microscope (AFM). Blasius boundary layer conditions for the flowing fluid defined a model that treated the solid, the dissolution/growth interface, and the fluid kinetics. Microscopic reversibility and the laws of large number s gave an expression for the back reaction activation energies in terms of the forward reaction energies and the entropy of mixing, a quantity estimated from the concentration of desorbates in a very small fluid layer adjacent to the interface. The KMC simulations produced cleavage-step morphologies that were in qualitative agreement with observations from AFM. The kinetics were dominated by diffusion events on the solid/fluid interface and in the fluid, as expected. The relative magnitudes of the desorption and adsorption activation energies were consistent with experimental data, entropic arguments, and crystal roughening theories. Qualitative agreement with measured step velocities was best when the boundary layer parameters were given physically reasonable values, indicating that the model is self consistent.

• Research Organization: Pacific Northwest National Lab., Richland, WA (US), Environmental Molecular Sciences Laboratory (US)
• Sponsoring Organization: US Department of Energy (US)
• DOE Contract Number: AC06-76RL01830
• OSTI ID: 15006480
• Report Number(s): PNNL-SA-39589; JCRGAE; 2192; 4391; KC0303020; TRN: US200506%%31
• Journal Information: Journal of Crystal Growth, Vol. 262, Issue 1-4; Other Information: PBD: 15 Feb 2004; ISSN 0022-0248
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
ADSORPTION
CALCITE
CLEAVAGE
DEFECTS
DESORPTION
DIFFUSION
DISSOLUTION
ENTROPY
REACTION KINETICS
WATER
CRYSTAL GROWTH
MONTE CARLO METHOD
ACTIVATION ENERGY
ENVIRONMENTAL MOLECULAR SCIENCES LABORATORY
B2. CALCITE
A1. ADSORPTION
A1. DESORPTION
A1. DIFFUSION
A1. GROWTH MODELS
A1. DEFECTS