CALCIUM CARBONATE INTERACTION WITH ORGANIC COMPOUNDS.

Dissolved organic compounds interact with the surface of calcium carbonate minerals and effect simple inorganic equilibration between solution and solid. Organo-carbonate associations form between stearic acid and calcite and dolomite, and between albumin and aragonite, calcite, and Mg-calcite. When stearic acid interacts with these minerals in hexane solution, a complete monolayer forms on the calcite surface, and half of a layer forms on the dolomite surface. When stearic acid and carbonate minerals interact in aqueous solution, the amount absorbed is not sufficient to form a complete monolayer of pure stearic acid, although hydrated surface complexes appear to be large enough to completely cover the surface of the minerals. At low concentrations in water, albumin forms a complete monolayer on carbonate minerals. At higher concentrations, multilayers or unoriented aggregates form. Organo-carbonate associations affect the calcium carbonate equilibrium in solution by physically isolating the mineral surface and by reducing the surface free energy of the solid. Surface seawater, deep water, and interstitial water show inorganic equilibration at different calcite to seawater ratios. These ratios are constant for one seawater sample whether equilibrium is approached from under- or oversaturation. Author