• Journal of Korean Society of Environmental Engineers
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• v.32 no.7
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• pp.714-721
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• 2010

This research was undertaken to evaluate the feasibility of lanthanum hydroxide for fluoride removal from aqueous solutions. A batch sorption experiments were conducted to study the influence of various factors such as pH, contact time, initial fluoride concentration and temperature on the sorption of fluoride on lanthanum hydroxide. The optimum fluoride removal was observed in the $pH_{eq}{\leq}8.8$. Sorption equilibrium of fluoride on lanthanum hydroxide was better described by the Freundlish isotherm model than by the Langmuir isotherm model. The adsorption energy obtained from D-R model was 9.21 kJ/mol indicating an ion-exchange process as primary adsorption mechanism. The pseudo-second-order kinetic model described well the experimental kinetic data. Thermodynamic parameters such as ${\Delta}Go^{\circ}$, ${\Delta}H^{\circ}$ and ${\Delta}S^{\circ}$ indicated that the nature of fluoride sorption is spontaneous and endothermic. The used lanthanum hydroxide could be regenerated by washing with NaOH solution. Also, the results applied to real ground water indicate that fluoride selectivity and removal capacity of lanthanum hydroxide were superior to those of PA anion-exchange resin.