Water defluoridation by Mexican heulandite-clinoptilolite

Fluorosis is caused by excess ingestion of fluoride. In this work, a natural Mexican zeolite (heulandite-clinoptilolite from Sonora) was evaluated for the sorption of fluoride ions from aqueous solutions and well-water. The effects of sodium, calcium, lanthanum, and europium in the crystalline network of this aluminosilicate, as well as, the effects of pH and particle size of the zeolite on the fluoride sorption were determined. It was found by x-ray diffraction, electronic microscopy, and IR that the structure of the material does not change after the retention of fluoride ions, and fluoride retention is not substantially affected by the cations (Na, Ca, La, and Eu) in the zeolite, the initial pH, or the particle size of the material studied. The K-d values obtained from the zeolitic mineral treated with La and Eu are slightly different from those obtained from both the untreated zeolitic mineral and the material treated with Na and Ca.