The calcite/water interface - II. Effect of added lattice ions on the charge properties and adsorption of sodium polyacrylate

The origin of the surface potential of calcium carbonate in aqueous dispersions and the dissolution of calcite in systems containing excess Ca2+ and CO32- have been the subjects of this study. In addition, stabilization of calcite particles with an anionic polyelectrolyte (sodium polyacrylate (NaPA)) and the effect on surface potential and dissolution of calcite have been studied. Preferential dissolution of either Ca2+ or CO32- from the surface, which is governed by the partial pressure of CO2 in solution and the pH of the solution, mainly determines the surface potential. Both lattice ions (Ca2+ and CO32- adsorb onto the surface and thus alter the surface potential. NaPA adsorbs strongly onto the calcite surface regardless of background electrolyte concentration, and reverses the surface potential to negative values. Chelation of the surface due to NaPA can be partly prevented by adding Ca2+ to the dispersion. (c) 2008 Elsevier Inc. All rights reserved.