초록
The adsorption features of fluoride ion on the oyster shell have been investigated for the purpose of the employment of waste oyster shell as an adsorbent for the treatment of fluoride ion-containing wastewater. The major component of oyster shell was examined to be Ca with minor components of Na, Si, Mg, Al, and Fe. As the initial concentration of fluoride ion was raised, its absorbed amount was enhanced at equilibrium, however, the adsorption ratio of fluoride ion compared with its initial concentration was shown to be decreased. Also, adsorption of fluoride ion onto the oyster shell resulted in the formation of $CaF_2$ in the morphological structure of adsorbent. Kinetic analysis showed that the adsorption reaction of fluoride ion generally followed a second order reaction with decreasing rate constant with the initial concentration of adsorbate. Freundlich model agreed well with the adsorption behavior of fluoride ion at equilibrium and the adsorption reaction of fluoride ion was examined to be endothermic. Several thermodynamic parameters for the adsorption reaction were calculated based on thermodynamic equations and the activation energy for the adsorption of fluoride ion onto oyster shell was estimated to be ca. 13.589 kJ/mole.