Abstract
AbstractDissolution is inherent to fluid‐mineral systems. Yet its impact on minerals reacting with electrolytes is overlooked. Here, a novel nonmonotonic behavior for the surface interactions of carbonates (calcite and Mg‐calcite) with organic acids is reported. Applying a bioinspired approach, Mg‐calcite sensors via amorphous precursors, avoiding any preconditioning with functional groups are synthesized. A quartz crystal microbalance is used to study the mass changes of the mineral on contact with organic acids under varying ionic conditions, temperatures, and flow velocities. Supported by confocal Raman microscopy and potentiometric titrations, nonmonotonous mass developments are found as a function of Ca2+concentration and flowrate, and attributed to three coupled chemical reactions: i) carbonate dissolution via Ca2+ion complexation with organic molecules, and the formation of organo‐calcium compounds as ii) a surface phase at the mineral–water interface, and iii) particles in the bulk fluid. These processes depend on local ion contents and the precipitation onset (i.e., saturation index) of organo‐calcium salts, both of which substantially differ in the bulk fluid and in the fluid boundary layer at mineral interfaces. This continuum between dissolution and precipitation provides a conceptual framework to address reactions at mineral interfacial across disciplines including biomineralization, ocean acidification and reservoir geochemistry.
Highlights
Carbonates are amenable to surface modiii) a surface phase at the mineral-water interface, and iii) particles in the bulk fications with organic species, utilized for fluid. These processes depend on local ion contents and the precipitation onset of organo-calcium salts, both of which substantially differ in the bulk fluid and in the fluid boundary layer at mineral interfaces
Originating from carbonate dissolution (Figure 1b), this interfacial fluid boundary layer can be supersaturated with respect to one or multiple mineral phases while the bulk fluid is not.[18]
Sorption events involving soluble adsorbents such as CaCO3 are still described by fitting of Langmuir and Freundlich models to adsorption isotherm data, which accounts neither for surface precipitation nor for mineral dissolution
Summary
(d) Dissolution/Precipitation of CaCO3 (related to the solubility product of calcite, KspCaCO3). Using a Quartz Crystal Microbalance with Dissipation monitoring (QCM-D), we investigate with high sensitivity the responses of the mineral mass to applied ionic conditions, nature of organic acids and temperature For this purpose, we introduce a new method to functionalize the QCM-D sensors with Mg-calcite. Additional compositional and structural insights for the organo-mineral interactions are gained from confocal Raman microscopy and potentiometric titrations By integrating these analytical approaches, we provide a physical framework to address the organic modifications of soluble minerals in relation to the distinct composition and structure of the mineral-water interface. In this manner, we elucidate a dynamic and nonmonotonic behavior for interface coupled dissolution-precipitation reactions involving organo-ionic complexes and precipitates, beyond the mechanisms assumed by classical isotherms
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
