title: Biotite-brine interactions under acidic hydrothermal conditions: fibrous illite, goethite, and kaolinite formation and biotite surface cracking.
abstract: To ensure safe and efficient geologic CO(2) sequestration (GCS), it is crucial to have a better understanding of CO(2)-brine-rock interactions under GCS conditions. In this work, using biotite (K(Mg,Fe)(3)AlSi(3)O(10)(OH,F)(2)) as a model clay mineral, brine-biotite interactions were studied under conditions relevant to GCS sites (95 °C, 102 atm CO(2), and 1 M NaCl solution). After reaction for 3-17 h, fast growth of fibrous illite on flat basal planes of biotite was observed. After 22-70 h reaction, the biotite basal surface cracked, resulting in illite detaching from the surface. Later on (96-120 h), the cracked surface layer was released into solution, thus the inner layer was exposed as a renewed flat basal surface. The cracking and detachment of the biotite surface layer increased the surface area in contact with solution and accelerated biotite dissolution. On biotite edge surfaces, Al-substituted goethite and kaolinite precipitated. In control experiments with water under the same temperature and pressure, neither macroscopic fibrous illite nor cracks were observed. This work provides unique information on biotite-brine interaction under acidic hydrothermal conditions.
authors.affiliation: Department of Energy, Environmental & Chemical Engineering, Washington University, St. Louis, Missouri 63130, USA.
authors.forename: Yandi
authors.initials: Y
authors.lastname: Hu
authors.forename: Jessica R
authors.initials: JR
authors.lastname: Ray
authors.forename: Young-Shin
authors.initials: YS
authors.lastname: Jun
mesh_terms: D000538:Aluminum Silicates / Q000737:chemistry*; D057965:Carbon Sequestration; D005296:Ferrous Compounds / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D058085:Iron Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D007616:Kaolin / Q000138:chemical synthesis* / Q000737:chemistry; D008903:Minerals / Q000138:chemical synthesis* / Q000737:chemistry; D011312:Pressure; D012623:Seawater / Q000737:chemistry*; D013052:Spectrometry, X-Ray Emission; D013499:Surface Properties; D013696:Temperature
chemical_list: D000538:Aluminum Silicates; D005296:Ferrous Compounds; D058085:Iron Compounds; D008903:Minerals; C099089:illite; C047410:biotite; C094886:goethite; D007616:Kaolin