Simulating the binding of key organic functional groups to aqueous calcium carbonate species

Abstract

The interaction of organic molecules with mineral systems is relevant to a wide variety of scientific problems both in the environment and minerals processing.

Monitoring of CaCO3 Nanoscale Structuration through Real-Time Liquid Phase Transmission Electron Microscopy and Hyperpolarized NMR

“…Our results are in agreement with recent MD simulations showing that complexation of calcium ion to carboxylate oxygens is favored for acetate and glycine in aqueous environment . Hence, l -Asp seems to regulate the presence of PNC and aggregated PNC in water through a double organic–inorganic interaction involving both the COO – groups and the NH 3 + to attract Ca 2+ and CO 3 2– /HCO 3 – , respectively, leading to nanometric entities observed in LP-TEM at the beginning of the mineralization process.…”

“…Indeed, a stable conformation is observed which is characterized by a complexation of the Ca 2+ −HCO Our results are in agreement with recent MD simulations showing that complexation of calcium ion to carboxylate oxygens is favored for acetate and glycine in aqueous environment. 78 Hence, L-Asp seems to regulate the presence of PNC and aggregated PNC in water through a double organic−inorganic interaction involving both the COO − groups and the NH 3 + to attract Ca 2+ and CO 3 2− /HCO 3 − , respectively, leading to nanometric entities observed in LP-TEM at the beginning of the mineralization process. Moreover, the strong affinity of aspartate for calcium carbonate was also shown through the use of L-and D-Asp to grow left-and righthanded vaterite toroids, respectively.…”

Determining the Adsorption Free Energies of Small Organic Molecules and Intrinsic Ions at the Terrace and Steps of Calcite

“…The fact that carbonate groups, to which amino groups preferentially bind, are less strongly hydrated than calcium ions could account for the smaller energy barriers amino groups are faced with when approaching the surface. Furthermore, amino group-containing species have less exergonic solvation free energies compared to carboxylatebearing molecules (−264 kJ/mol for methylammonium vs −330 kJ/mol for acetate 39 ) and thus interact less strongly with their hydration shell. This makes the case of glycine, containing both an amino and carboxylate group, particularly interesting.…”

“…38 Recently, this model was extended to include the interaction with small organics that contain two of the key functional groups believed to be relevant to adsorption on calcite. 39 In this work, we use classical MD based on both polarizable and rigid-ion force fields to investigate the interactions of carboxylate and ammonium functional groups with calcite, by studying the adsorption of acetate, methylammonium, and zwitterionic glycine, along with the constituent mineral ions, calcium, and carbonate, onto the basal plane and steps of the {101̅ 4} surface of calcite. Implications for calcite growth inhibition or promotion by organic additives will be discussed, as well as the effect of accounting for polarization in the modeling of adsorption processes.…”

“…It has been successfully applied to the solid phase and found to compare well with experiments and DFT in describing the calcite {101̅4}–water interface . Recently, this model was extended to include the interaction with small organics that contain two of the key functional groups believed to be relevant to adsorption on calcite . In this work, we use classical MD based on both polarizable and rigid-ion force fields to investigate the interactions of carboxylate and ammonium functional groups with calcite, by studying the adsorption of acetate, methylammonium, and zwitterionic glycine, along with the constituent mineral ions, calcium, and carbonate, onto the basal plane and steps of the {101̅4} surface of calcite.…”