ADSORPTION AND COPRECIPITATION OF PHOSPHATE ON CALCITE

The adsorption of inorganic phosphate ( less than 20 mu mole dm** minus **3) from dilute aqueous solutions in equilibrium with calcite has been reported for two cyrstalline samples of calcite over a range of temperatures from 5 to 35 degree C and pH of 7 to 9. 5. A simple two-component model of adsorption describes the isotherms and their pH dependence. The model has been applied to the coprecipitation of phosphate with calcite at various precipitation rates and in a temperature range of 5 to 25 degree C. The results indicate that only a fraction of the total adsorbed phosphorus is incorporated into the growing cyrstals and that the rate of adsorption of this fraction does not determine the coprecipitation rate in the experiments.