| Abstract |
| In this study, fluoride removal using attapulgite (ATTP) was investigated and thermal treatment was performed on the ATTP to improve its adsorption capacity of fluoride. Adsorption experiments were performed under batch conditions. Fluoride adsorption capacity of thermally treated attaplugites increased with increasing thermal treatment temperature and showed the highest adsorption capacity at 700°C (ATTP-700). As a result of kinetic experiment and model analysis, fluoride adsorption on ATTP-700 reached equilibrium after 6 hours and adsorption rate was mainly influenced by chemical adsorption. The equilibrium adsorption experiment showed that the maximum fluoride adsorption amount of ATTP-700 was 4.85 mg/g and was more suitable for the Langmuir model than the Freundlich model. Thermodynamic adsorption experiments showed that fluoride adsorption of ATTP-700 was endothermic and non spontaneous. Highest fluoride adsorption was achieved at pH 3. As the increase of ATTP-700 dose, the percentage of fluoride removal increased, but the amount of fluoride removal per unit mass of the adsorbent was reduced. Different molar fraction of phosphate and fluoride showed that phosphate adsorption onto ATTP-700 was more favorable than fluoride adsorption. ATTP-700 is inexpensive but highly effective for the removal of fluoride from water. |
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| Key Words |
| Attapulgite, Thermal treatment, Fluoride adsorption, pH, Mole fractions |
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