title: Distinctive Reactivities at Biotite Edge and Basal Planes in the Presence of Organic Ligands: Implications for Organic-Rich Geologic CO2 Sequestration.
abstract: To better understand how scCO2-saturated brine-mineral interactions can affect safe and efficient geologic CO2 sequestration (GCS), we studied the effects of organic ligands (acetate and oxalate) on biotite dissolution and surface morphological changes. The experimental conditions were chosen to be relevant to GCS sites (95 °C and 102 atm CO2). Quantitative analyses of dissolution differences between biotite edge and basal planes were made. Acetate slightly inhibited biotite dissolution and promoted secondary precipitation. The effect of acetate was mainly pH-induced aqueous acetate speciation and the subsequent surface adsorption. Under the experimental conditions, most of acetate exists as acetic acid and adsorbs to biotite surface Si and Al sites, thereby reducing their release. However, oxalate strongly enhanced biotite dissolution and induced faster and more significant surface morphology changes by forming bidentate mononuclear surface complexes. For the first time, we show that oxalate selectively attacks edge surface sites and enhances biotite dissolution. Thus, oxalate increases the relative reactivity ratio of biotite edge surfaces to basal surfaces, while acetate does not impact this relative reactivity. This study provides new information on reactivity differences at biotite edge and basal planes in the presence of organic ligands, which has implications for safe CO2 storage in organic-rich sites.
authors.affiliation: Department of Energy, Environmental and Chemical Engineering, Washington University in St. Louis, One Brookings Drive, Campus Box 1180, St. Louis, Missouri 63130, United States.
authors.forename: Lijie
authors.initials: L
authors.lastname: Zhang
authors.affiliation: Department of Energy, Environmental and Chemical Engineering, Washington University in St. Louis, One Brookings Drive, Campus Box 1180, St. Louis, Missouri 63130, United States.
authors.forename: Young-Shin
authors.initials: YS
authors.lastname: Jun
mesh_terms: D000085:Acetates / Q000737:chemistry; D000327:Adsorption; D000538:Aluminum Silicates / Q000737:chemistry*; D016880:Anisotropy; D002245:Carbon Dioxide / Q000032:analysis*; D057965:Carbon Sequestration; D011232:Chemical Precipitation; D005296:Ferrous Compounds / Q000737:chemistry*; D019015:Geologic Sediments / Q000737:chemistry*; D008024:Ligands; D018625:Microscopy, Atomic Force; D008903:Minerals / Q000737:chemistry; D009930:Organic Chemicals / Q000737:chemistry*; D010070:Oxalates / Q000737:chemistry; D012996:Solutions; D013997:Time Factors
chemical_list: D000085:Acetates; D000538:Aluminum Silicates; D005296:Ferrous Compounds; D008024:Ligands; D008903:Minerals; D009930:Organic Chemicals; D010070:Oxalates; D012996:Solutions; C047410:biotite; D002245:Carbon Dioxide