The electrokinetics of apatite and calcite in inorganic electrolyte environment

Microelectrophoresis technique was used to study the electrokinetic properties of some apatites and calcite. The results indicate that similar to oxide minerals, H⁺ and OH^? ions function as potential-determining ions for apatite and calcite. However, because of their variable compositions, the apatites from different deposits showed different i.e.p. values ranging from pH 3.5 to 6.7, while the i.e.p. of calcite occurred at pH 8.2.Study of the effect of lattice-forming ions on the zeta potential indicates that calcium ions produce specific ionic adsorption effects on apatites, whereas they are potential-determining ions for calcite. On the other hand, as expected, phosphate and carbonate ions function as potential-determining ions for apatite and calcite, respectively.The experimental data suggest that the zeta potential of apatite is a function of mineral—water contact time. The degree of variation in zeta-potential values appears to be influenced by the electrolytic environment of the apatite suspension.