In Situ Observation of Biotite Dissolution at pH 1 Using Advanced Optical Microscopy

Abstract

Laser confocal microscopy with differential interference contrast microscopy (LCM-DIM) was used to study in situ the biotite (001) basal surface dissolution performing long-term flow-through experiments at pH 1 (T = 11.5–70 °C). Time-lapse image sequences of large areas (up to 1 mm) of the evolving cleavage (001) surface showed that dissolution only occurs at surface edges. In addition, in contrast to an observed rapid dissolution at low steps (few layers), swelling and contraction of the edge layers occurred at high steps (many layers). An increase in temperature enhanced the surface edge dissolution from 7.5 × 10–4 μm s–1 at 11.5 °C to 6.2 × 10–2 μm s–1 at 70 °C. The results obtained in this work demonstrate that LCM-DIM is a powerful technique to study in situ the dissolution mechanism and kinetics of phyllosilicates.

Reactivity of micas and cap-rock in wet supercritical CO2 with SO2 and O2 at CO2 storage conditions

“…to selective leaching of interlayer K and Na, and octahedral Mg, Fe, and Al cations at low pH to form a silica-enriched area, and is postulated to be occurring in the current experiments (Murakami et al, 2003). Cation leaching has previously been observed to lead to biotite layers swelling and subsequently curling and peeling off (Cappelli et al, 2013). Biotite interlayer peeling and cracking with dissolved CO -brine reaction has also been previously observed (Hu and Jun, 2012;Hu et al, 2011).…”

The effect of pH, grain size, and organic ligands on biotite weathering rates

“…S5, Table 1), demonstrating the importance of grain geometry on the overall dissolution rate. Like biotite, other sheet silicates have been shown to primarily dissolve parallel to the basal surface, i.e., at the (h k 0) surfaces (Kaviratna and Pinnavaia, 1994;Turpault and Trotignon, 1994;Bosbach et al, 2000;Bickmore et al, 2001Bickmore et al, , 2003Aldushin et al, 2006;Hodson, 2006;Saldi et al, 2007;Cappelli et al, 2013).…”

Biotite surface chemistry as a function of aqueous fluid composition

“…and increase thereafter with increasing pH (Lin and Clemency, 1981a;Lin and Clemency, 1981b;Acker and Bricker, 1992;Turpault and Trotignon, 1994;Kalinowski and Schweda, 1996;Malmstr m et al, 1996;Malmstr m and Banwart, 1997;Brandt et al, 2003;Balogh-Brunstad et al, 2008;Balland et al, 2010;Haward et al 2011;Cappelli et al, 2013;Voinot et al, 2013). As the pH of minimum biotite dissolution rate (~ pH 7) differs from both pH IEP (3.02) and pH imm (9.66), it is clear that the biotite dissolution rates are not directly related to proton consumption at the surface.…”