Importance of surface structure on dissolution of fluorite: implications for surface dynamics and dissolution rates.
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Importance of surface structure on dissolution of fluorite : implications for surface dynamics and dissolution rates. / Godinho, Jose; Piazolo, Sandra; Balic Zunic, Tonci.
I: Geochimica et Cosmochimica Acta, Bind 126, 2014, s. 398-410.Publikation: Bidrag til tidsskrift › Tidsskriftartikel › Forskning › fagfællebedømt
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TY - JOUR
T1 - Importance of surface structure on dissolution of fluorite
T2 - implications for surface dynamics and dissolution rates.
AU - Godinho, Jose
AU - Piazolo, Sandra
AU - Balic Zunic, Tonci
PY - 2014
Y1 - 2014
N2 - Dissolution rates are usually calculated as a function of surface area, which is assumed to remain constant ignoring the changes occurring on the surface during dissolution. Here we present a study of how topography of natural fluorite surfaces with different orientation changes during up to 3200 h of dissolution. Results are analyzed in terms of changes in surface area,surface reactivity and dissolution rates. All surfaces studied present fast changes in topography during the initial 200 h of dissolution. The controlling factors thatcause the development of topography are the stability of the step edges forming the initial surface and its inclination to the closest stable planes, which are specific for each surface orientation. During an initial dissolution regime dissolution rates decrease significantly, even though the total surface area increases. During a second dissolution regime, some surfaces continueto present significant changes in topography, while for others the topography tends to remain approximately constant. The observed variation of dissolution rates are attributed to a decrease of the density of step edges on the surface and the continuous increase in exposure of more stable surfaces. Calculations of dissolution rates, which assume that dissolution rates are directly proportional to surface area, are not valid for the type of surfaces studied. Instead, to develop accurate kinetic dissolution models and more realistic stochastic dissolution simulations the surface reactivity, determined by the relative stability of the planes and type of edges that constitute a surface needs to be considered. Significant differences between dissolution rates calculated based on surface area alone, and based on surface reactivity are expected for materials with the fluorite structure.
AB - Dissolution rates are usually calculated as a function of surface area, which is assumed to remain constant ignoring the changes occurring on the surface during dissolution. Here we present a study of how topography of natural fluorite surfaces with different orientation changes during up to 3200 h of dissolution. Results are analyzed in terms of changes in surface area,surface reactivity and dissolution rates. All surfaces studied present fast changes in topography during the initial 200 h of dissolution. The controlling factors thatcause the development of topography are the stability of the step edges forming the initial surface and its inclination to the closest stable planes, which are specific for each surface orientation. During an initial dissolution regime dissolution rates decrease significantly, even though the total surface area increases. During a second dissolution regime, some surfaces continueto present significant changes in topography, while for others the topography tends to remain approximately constant. The observed variation of dissolution rates are attributed to a decrease of the density of step edges on the surface and the continuous increase in exposure of more stable surfaces. Calculations of dissolution rates, which assume that dissolution rates are directly proportional to surface area, are not valid for the type of surfaces studied. Instead, to develop accurate kinetic dissolution models and more realistic stochastic dissolution simulations the surface reactivity, determined by the relative stability of the planes and type of edges that constitute a surface needs to be considered. Significant differences between dissolution rates calculated based on surface area alone, and based on surface reactivity are expected for materials with the fluorite structure.
U2 - 10.1016/j.gca.2013.11.017
DO - 10.1016/j.gca.2013.11.017
M3 - Journal article
VL - 126
SP - 398
EP - 410
JO - Geochimica et Cosmochimica Acta
JF - Geochimica et Cosmochimica Acta
SN - 0016-7037
ER -
ID: 122608078