THE MECHANISM OF FLUORINE REMOVAL BY CALCIUM SALTS- PART 1

Abstract

The reaction between a sodium fluoride solution and calcium oxide, sulphate, carbonate, rock phosphate, fluorapatite and chlorapatite has been studied. It is shown (i) that rock phosphate, fluorapatite and chlorapatite do not enter into any reaction with the dissolved fluoride;(ii) that calcium oxide and sulphate remove fluorine from its aqueous solution by the mechanism of double decomposition, wherein the solubility of the precipitated calcium fluoride is the limiting factor for the complete removal of fluorine, and (iii) that calcium carbonate removes fluorine in the manner that can be mathematically denoted by the Freundlich adsorption isotherm. The peculiarities of the reaction between calcium carbonate and a solution of sodium fluoride are indicated.