2002 Volume 9 Issue 300 Pages 271-275
The enthalpies as well as the amount of interaction of Pb2+, Cu2+, Hg+ and Ag+ ions in the aqueous nitrate solution were studied with calcium hydroxyapatite (HAp) surfaces of different Ca/P atomic ratio by means of flow adsorption microcalorimetry. Pb2+ ion interacted with HAp surface almost irreversibly with a large heat of reaction. The amount of Pb2+ interacted with HAp surface corresponds to about 2 ionic surface layers of Ca2+ ions of HAp. The interaction behaviour of Hg2+ with HAp was similar to that of Pb2+. The enthalpies of ion exchange interaction of Cu2+ and Ag+ were smaller than that of Pb2+. The mechanism of interaction of these ions was discussed in view of the heat of interaction.
