Adsorption of zinc and copper ions on calcite and aragonite and its influence on the transformation of aragonite to calcite

Abstract

Adsorption of zinc and copper ions on calcite and aragonite has been measured by suspending powdered calcite or aragonite in various solutions containing zinc and copper ions. The amounts of copper adsorbed on calcite and aragonite in pure water are smaller than those in seawater, whereas those of zinc in pure water are larger than those in seawater. The extent of the adsorption on calcite and aragonite depends on the procedures for the formation of the calcite and aragonite. The influence of zinc and copper ions in solution on the transformation of aragonite to calcite, has been further studied. Results obtained are as follows: The presence of zinc ions in solution inhibits very strongly the transformation of aragonite to calcite. About 90 per cent of zinc ions in the solution is adsorbed by aragonite. The presence of copper ions, however, does not inhibit it, even though copper ions in solution are removed completely through its adsorption on aragonite.