Alteration of trioctahedral micas in the presence of inorganic and organic acids
Metadatos
Afficher la notice complèteAuteur
Cappelli, Chiara; Van Driessche, Alexander Edgard Suzanne; Cama, Jordi; Huertas Puerta, Francisco JavierEditorial
Elsevier
Materia
Laser confocal microscopy Interferometry AFM Dissolution Organic acid Mica Phlogopite
Date
2023-03-28Referencia bibliográfica
C. Cappelli et al. Alteration of trioctahedral micas in the presence of inorganic and organic acids. Applied Clay Science 238 (2023) 106923[https://doi.org/10.1016/j.clay.2023.106923]
Patrocinador
CGL2011–22567; CGL2014–55108-P; CGL2016–78783–C2-R; CGL2017–82331-R; CEX2018–000794-S projects (Spanish Ministry of Science and Innovation) and the Catalan project 2021 SGR 00308. IDAEA-CSIC is a Severo Ochoa Centre of Excellence (Spanish Ministry of Science and Innovation; Project CEX2018-000794-S).Résumé
The alteration of two trioctahedral micas, biotite and phlogopite, was investigated at the meso, micro, and
nanoscale using three complementary microscopy techniques to better understand mica surface reactivity. In situ
and ex situ experiments were performed to monitor the mineral interface during dissolution in acidic solutions
(nitric and oxalic acid, pH ~ 1–2), over a temperature range of 25–100◦C. The inorganic acid was used as a
benchmark condition to elucidate the effect of the organic acid on the dissolution behavior. The observed
topographical changes that arose during mineral alteration revealed the simultaneous occurrence of different
processes that heterogeneously shaped the mica surface: 1) the retreat of pre-existing and newly formed steps
(edge surface reactivity). In the case of biotite, layer curling and peeling-off occurred in the presence of nitric
acid whereas dendritic-shaped step edges resulted from the effect of oxalic acid; 2) the nucleation of etch pits and
the formation of dissolution channels on the (001) surface. Oxalic acid promoted the growth of the pits to such an
extent that they were discernible at each scale and resolution investigated; and 3) precipitation of secondary
phases. Overall, a multi-scale approach offers new insights into the dissolution behavior of biotite versus
phlogopite and provides and enhances understanding of the effect that oxalic acid has on the surface reactivity of
mica.