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FLUORIDATION CHEMISTRY: EQUILIBRIA AND KINETICS OF FLUORIDE AND FLUORO-COMPLEXES
Urbansky*, E T., T. G. Reeves, D A. Lytle*, C Feld*, AND M R. Schock*. FLUORIDATION CHEMISTRY: EQUILIBRIA AND KINETICS OF FLUORIDE AND FLUORO-COMPLEXES. Presented at American Chemical Society National Meeting, Chicago, IL, 8/29/2001.
The most common fluoridating agents used by major American waterworks are hexafluorosilicic acid (H2SiF6) and sodium hexxafluorosilicate (Na2SiF6). According to the 1992 Water Fluoridation Census where 10,002 utilities responded affirmatively to fluoridating their water, 59
% used H2SiF6, 16% used Na2SiF6 and 25% used NaF. Both H2SiF6 and Na2SiF6 are commonly obtained as byproducts of the fertilizer industry when phosphate rock (a mixture of fluorapatite and other miners) is processed. H2SiF6 is sold as a concentrated solution that contains a significant concentration of HF(aq) to prevent dissociation and hydrolysis of the H2SiF6. When H2SiF6 is diluted into a water supply, it undergoes dissociation and hydrolysis.