Title: Effects of Na+ and K+ Exchange in Interlayers on Biotite Dissolution under High-Temperature and High-CO2 -Pressure Conditions

Journal Article · · Environmental Science and Technology

Cations in formation brine can affect CO2-induced dissolution of minerals during geologic CO2 sequestration (GCS), affecting the GCS performance. This study investigated the dissolution of biotite with 0–4 M Na+ and 0–10 mM K+ under high temperature and high CO2 pressure (i.e., 95 °C and 100 bar CO2). At <0.5 M Na+ concentration, Na+ replaced K+ in the biotite interlayer and enhanced the biotite dissolution. In >0.5 M Na+, however, the enhancing effect of Na+ was mitigated by an inhibition caused by competing sorption between Na+ and protons. With 0.5 M Na+ concentration, coexisting K+ significantly inhibited the biotite dissolution with high sensitivity at even lower K+ concentrations, such as 0.1–0.5 mM. In this study, we also reported the dissolution of Na-treated biotite, mimicking biotite naturally equilibrated with Na+-abundant brine. Na-treated biotite dissolved faster than natural K-containing biotite, and during the dissolution, it transformed to vermiculite. Aqueous Na+ inhibited the dissolution of Na-treated biotite by suppressing the release of interlayer Na+, and aqueous K+ inhibited the dissolution of Na-treated biotite by replacing the interlayer Na+. In conclusion, these findings contribute to better understanding of biotite dissolution in the presence of potassium-containing clay-swelling inhibitors and different salinities at GCS sites.

Research Organization:
Energy Frontier Research Centers (EFRC) (United States). Center for Nanoscale Control of Geologic CO2 (NCGC); Univ. of California, Oakland, CA (United States)
Sponsoring Organization:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Grant/Contract Number:
AC02-05CH11231
OSTI ID:
1566496
Journal Information:
Environmental Science and Technology, Journal Name: Environmental Science and Technology Journal Issue: 22 Vol. 52; ISSN 0013-936X
Publisher:
American Chemical Society (ACS)Copyright Statement
Country of Publication:
United States
Language:
English