Adsorption of fluoride on soil of Misiones province

STIJN BRUNEEL; ANALIA IRIEL,; NAHUEL SCHENONE; ALICIA FERNÁNDEZ CIRELLI

Congreso; Argentina y Ambiente 2015; 2015

Fluorideis present in environmental matrixes (air, water and soil) due to both naturaland anthropogenic activities. Natural presence of fluoride in groundwater isrelated to the geological environment in the aquifers and is mediated byphysical and chemical processes. Usually, concentrations in groundwater rangefrom values lower than 0.01 to more than 10 mg/L. In the case of anthropogenicactivities such as factories of metal processing, fertilizers, andglass-manufacturing industries, higher concentrations can be found inwastewater where the maximum concentration allowed to be discharged is 15-20mg/L. Humanand animals exposure, basically from drinking water, has both beneficial and apernicious effects in the organism health depending on the uptake doses. Theuse of natural sorbents to remove it from drinking water is a promisingalternative due to low costs and easy implementation. In particular, sorbentswith high iron content are more efficient in fluoride removal.Inthis work, the physicochemical process of fluoride adsorption on a latosol soilfrom Misiones province was studied regarding kinetics and equilibrium aspects.Experiments were conducted in batch conditions at set values of pH, ionic forceand temperature. Asa result, a second order kinetic was found while the constant rate seemed to bedependent with the pH of the solution. In addition, non significant differenceswere found for the removal capacity at the ionic forces studied (1x10-3M, 6x10-3 M and 1x10-2 M KNO3). Additionally, adsorptionisotherms at T=22 ºC, pH=8 and 1x10-3 M of KNO3 wereconstructed and modelled by using Langmuir, Freundlich and Dubinin-Raduskevichequations.