%0 Journal Article
%T Sorption of fluoride by quartz sand: batch tests
%A Eduardo Usunoff
%A Pablo Winzettel
%A Sebasti芍n Dietrich
%J Geoacta
%D 2009
%I Asociaci車n Argentina de Geof赤sicos y Geodestas
%X Despite the many efforts of scientists, in particular those from the field of soil science, the fate and distribution of fluorine (F) species in soils and aquifers remain relatively unraveled. As for groundwater systems, such a shortcoming makes difficult the finding and development of safe water supplies. Likewise, the use of transport models does not render acceptable results because of the many uncertainties related to the behavior of F in aqueous media. This paper presents the results of four batch test in which solutions of different pH and [F-] (concentration of fluoride) were in contact during 48 hours with clean quartz sand grains. The resulting data were fitted by linear versions of the Freundlich, the Langmuir, and the Langmuir-Freundlich models. The [F-] was varied between 0,5 and 10 mg L-1, except in one batch where a large initial concentration of F was used (45 mg L-1), and the range of pH used was 2,95 to 5,02. From a sieve analysis, the quartz grains had a medium size (d50) of 0,25 mm, and a uniformity coefficient (d40/d90) of 1,65. According to the fits and some dedicated goodness of fit indices, the Langmuir-Freundlich approach gave the best results for the batch test at the lowest pH, whereas the three remaining tests data were fitted by the Freundlich equation. It has to be mentioned that the pH of the equilibrium solutions were higher than the pH of the initial solutions, which was interpreted as an exchange process of OH- by F- on the quartz sand surface. However, such an exchange does not stand out as the exclusive mechanism promoting the F- disappearance from solution. It is deemed that the obtained results can be used as initial estimates of parameters in models used for calibrating the transport of F- in aquifers. A pesar de los muchos esfuerzos de los cient赤ficos, en particular de aquellos dedicados a las ciencias del suelo, el destino y la distribuci車n de las especies de F (fl迆or) en suelos y acu赤feros contin迆an siendo aspectos no mayormente dilucidados. Con referencia a los sistemas hidrol車gicos, tales indefiniciones plantean dificultades con respecto a la identificaci車n y desarrollo de fuentes seguras de agua para abastecimiento. De igual modo, los modelos de transporte no brindan resultados aceptables por las incertidumbres relacionadas con el comportamiento del F en medios acuosos saturados. Este trabajo presenta los resultados de cuatro ensayos en lote en los que soluciones de diferente pH y [F-] (concentraci車n de fluoruro) permanecieron en contacto durante 48 horas con granos limpios de arena cuarzosa. Los datos resultan
%K Adsorci車n de F-
%K Isotermas
%K Ensayos en lote
%K F- sorption
%K Isotherms
%K Batch tests
%U http://www.scielo.org.ar/scielo.php?script=sci_arttext&pid=S1852-77442009000100002