Interactions of the Calcite {10.4} Surface with Organic Compounds: Structure and Behaviour at Mineral – Organic Interfaces

Abstract

The structure and the strength of organic compound adsorption on mineral surfaces are of interest for a number of industrial and environmental applications, oil recovery, CO2 storage and contamination remediation. Biomineralised calcite plays an essential role in the function of many organisms that control crystal growth with organic macromolecules. Carbonate rocks, composed almost exclusively of calcite, host drinking water aquifers and oil reservoirs. In this study, we examined the ordering behaviour of several organic compounds and the thickness of the adsorbed layers formed on calcite {10.4} surfaces. We used X-ray reflectivity (XRR) to study calcite {10.4} surfaces that were prepared in three alcohols: methanol, isopropanol and pentanol and one carboxylic acid: octanoic acid. All molecules adsorbed in self-assembled layers, where thickness depended on the density and the length of the molecule. For methanol and isopropanol, molecular dynamic simulations (MD) provided complementary information, which allowed us to develop a surface model. Branching in isopropanol induced slightly less ordering because of the additional degree of freedom. Pentanol and octanoic acid adsorbed as single monolayers. The results of this work indicate that adhered organic compounds from the surrounding environment can affect the surface behaviour, depending on properties of the organic compound.

Mineral Surface-Templated Self-Assembling Systems: Case Studies from Nanoscience and Surface Science towards Origins of Life Research

“…These ethanol molecules adsorb perpendicular to the mineral surface in a highly ordered manner, while the second ethanol layer is much thicker, slightly less ordered, and is separated from the first layer by a gap. All of the polar hydroxyl groups in the first ethanol layer are oriented towards the ionic calcite surface, while the non-polar ends of the ethanol are oriented away from the mineral surface; this was also observed in studies with other alcohols like pentanol and propanol [ 44 ]. If the upper layer is removed, then the assembly of single alcohol monolayers onto calcite or any other mineral would change the surface to be hydrophobic.…”

“…In addition to adsorption of biomonomers such as nucleotides and amino acids, mineral surfaces are able to adsorb or interact with other various small organics including small carboxylic acids like salicylic acid onto kaolinite (Al 2 Si 2 O 5 (OH) 4 ) and aluminum oxide (Al 2 O 3 ) [ 43 ] and simple alcohols such as methanol or isopropanol onto calcite (CaCO 3 ) [ 44 ]. The adsorption of these small organic molecules is often governed by the functional groups on a given molecule, the structure and charge of the mineral surface, and also the solvent [ 43 ], often generating mono- or poly-layers of the small organic molecule on the mineral surface [ 44 , 45 , 46 ]. Ordered surface organic layers (in this case, stearic acid) have even been studied in the context of calcite crystal nucleation [ 47 ].…”

Setting behavior and bioactivity assessment of calcium carbonate cements

“…20 Due to its length, it has been used as a cross-linker agent in several industries, including coatings and pharmaceutics, 21,22 and consequently it is an interesting candidate to provide self-healing properties to cement pastes. The carboxyl group of octanoic acid is known to absorb on calcite surfaces as monolayers 23 and can either inhibit further calcite growth or enhance it by templating. Two different concentrations, 0.4 and 0.8 vol%, of octanoic acid (OA) (Sigma-Aldrich) were added to the water phase prior to mixing with the solid phase.…”

Construction of LiMn2O4 microcubes and spheres via the control of the (104) crystal planes of MnCO3 for high rate Li-ions batteries

“…The hydrophilic hydroxyl group of the ethanol molecule strongly interacts with the oxygen on the (104) crystal planes, and at the same time, the hydrophobic group -CH 3 is exposed to the outside to form an extremely stable and orderly hydrophobic adsorption layer. 27,31,33 The existence of the adsorption layer seriously reduces the growth ability of the (104) crystal planes in the vertical direction, 30 changes the surface energy and the MnCO 3 particles gradually undergo directional crystallization, and the blocks are densely packed into spheres. Also, the hydroxyl group is present in the pure water reaction system, where the lowest surface energy is stabilized, especially if its adsorption capacity is insufficient to change the equilibrium shape.…”

“…29 In particular, some organic substances (for example, ethanol) have strong interactions between the (104) crystal planes. 27,[30][31][32][33][34] Based on the relative theories above, we prepared a MnCO 3 cube precursor with highly exposed (104) crystal planes using a hydrothermal method without strict control of the pH and the addition of a structure directing agent, and changed the crystal stacking mode by simply adding ethanol solvent into the spherical material without changing the other conditions. The corresponding microporous cubic and spherical LiMn 2 O 4 materials were then obtained by selftemplated thermal decomposition and lithiation reactions and used as cathode materials for lithium ion batteries, wherein the cubic and spherical LiMn 2 O 4 exhibited good cycling performance and rate performance, and the lithium ion diffusion ability was signicantly improved.…”