brine and feldspar

Evaluation of CO₂ solubility-trapping and mineral-trapping by microbial-mediated process was investigated by lab experiments in this study. The results verified that microbes could adapt and keep relatively high activity under extreme subsurface environment (pH<5, temperature>50 °C, salinity>1.0 mol/L). When microbes mediated in the CO₂-brine-sandstone interaction, the CO₂ solubility-trapping was enhanced. The more biomass of microbe added, the more amount of CO₂ dissolved and trapped into the water. Consequently, the corrosion of feldspars and clay minerals such as chlorite was improved in relative short-term CO₂-brine-sandstone interaction, providing a favorable condition for CO₂ mineral-trapping. Through SEM images and EDS analyses, secondary minerals such as transition-state calcite and crystal siderite were observed, further indicating that the microbes played a positive role in CO₂ mineral trapping. As such, bioaugmentation of indigenous microbes would be a promising technology to enhance the CO₂ capture and storage in such deep saline aquifer like Erdos, China.

Topics: Aluminum Silicates; Calcium Carbonate; Carbon Dioxide; China; Clay; Clostridium; Groundwater; Hydrogen-Ion Concentration; Klebsiella; Minerals; Plesiomonas; Potassium Compounds; Salinity; Salts; Solubility; Temperature; Water Microbiology; Water Pollutants

Organic compounds in deep saline aquifers may change supercritical CO(2) (scCO(2))-induced geochemical processes by attacking specific components in a mineral's crystal structure. Here we investigate effects of acetate and oxalate on alkali feldspar-brine interactions in a simulated geologic carbon sequestration (GCS) environment at 100 atm of CO(2) and 90 °C. We show that both organics enhance the net extent of feldspar's dissolution, with oxalate showing a more prominent effect than acetate. Further, we demonstrate that the increased reactivity of Al-O-Si linkages due to the presence of oxalate results in the promotion of both Al and Si release from feldspars. As a consequence, the degree of Al-Si order may affect the effect of oxalate on feldspar dissolution: a promotion of ~500% in terms of cumulative Si concentration was observed after 75 h of dissolution for sanidine (a highly disordered feldspar) owing to oxalate, while the corresponding increase for albite (a highly ordered feldspar) was ~90%. These results provide new insights into the dependence of feldspar dissolution kinetics on the crystallographic properties of the mineral under GCS conditions.

Topics: Acetates; Aluminum Silicates; Carbon Sequestration; Geological Phenomena; Molecular Structure; Oxalates; Potassium Compounds; Salts