title: In situ observation of biotite (001) surface dissolution at pH 1 and 9.5 by advanced optical microscopy.
abstract: Laser confocal differential interference contrast microscopy (LCM-DIM) allows for the study of the reactivity of surface minerals with slow dissolution rates (e.g., phyllosilicates). With this technique, it is possible to carry out in situ inspection of the reacting surface in a broad range of pH, ionic strength and temperature providing useful information to help unravel the dissolution mechanisms of phyllosilicates. In this work, LCM-DIM was used to study the mechanisms controlling the biotite (001) surface dissolution at pH 1 (11 and 25 °C) and pH 9.5 (50 °C). Step edges are the preferential sites of dissolution and lead to step retreat, regardless of the solution pH. At pH 1, layer swelling and peeling takes place, whereas at pH 9.5 fibrous structures (streaks) form at the step edges. Confocal Raman spectroscopy characterization of the reacted surface could not confirm if the formation of a secondary phase was responsible for the presence of these structures.
authors.affiliation: Instituto Andaluz de Ciencias de la Tierra (IACT - CSIC-Universidad de Granada), Avda. de las Palmeras 4, 18100 Armilla, Granada, Spain.
authors.forename: Chiara
authors.initials: C
authors.lastname: Cappelli
authors.affiliation: Instituto Andaluz de Ciencias de la Tierra (IACT - CSIC-Universidad de Granada), Avda. de las Palmeras 4, 18100 Armilla, Granada, Spain.
authors.forename: Daniel
authors.initials: D
authors.lastname: Lamarca-Irisarri
authors.affiliation: Institute of Environmental Assessment and Water Research (IDAEA), CSIC, Jordi Girona 18-26, 08034 Barcelona, Spain.
authors.forename: Jordi
authors.initials: J
authors.lastname: Camas
authors.affiliation: Instituto Andaluz de Ciencias de la Tierra (IACT - CSIC-Universidad de Granada), Avda. de las Palmeras 4, 18100 Armilla, Granada, Spain.
authors.forename: F Javier
authors.initials: FJ
authors.lastname: Huertas
authors.affiliation: Structural Biology Brussel, VUB, Pleinlaan 2, 1050 Brussels, Belgium.
authors.forename: Alexander E S
authors.initials: AE
authors.lastname: Van Driessche
keywords: biotite; dissolution mechanism; environmental; in situ observation; pH effect
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