| Abstract |
| In this study, we investigated the characteristics of fluoride removal and adsorption onto calcined pig bone waste. The pig bone waste was calcined to enhance its adsorption capacity for fluoride and the thermal treatment was performed at different temperatures (100-900℃). Pig bones thermally treated at 500℃ (PB500) were found to have the highest adsorption capacity for fluoride. The time to reach equilibrium for fluoride adsorption onto PB500 was 3 hours at a fluoride concentration of 100 mg/L. Equilibrium experiments showed that fluoride adsorption onto PB500 was better described by Langmuir model than the Freundlich model, indicating that fluoride adsorbs onto PB500 as a monolayer. The 1/n value of the Freundlich model is less than 0.5, indicating that the bonding between fluoride and PB500 was strong. Thermodynamic experiments showed that fluoride adsorption onto PB500 is endothermic and non-spontaneous. As the pH of the fluoride solution increased from 3 to 11, the amount of fluoride adsorption onto PB500 was decreased. The presence of SO42- and PO43- decreased the adsorption of fluoride onto PB500, but the fluoride adsorption was not affected by the increase of Cl- concentration. Although the fluoride removal ratio increased with increasing dosing amount of PB500, the amount of fluoride removal per unit mass of adsorbent decreased. PB500 was proven to be a cheap and efficient adsorbent for the fluoride removal. |
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| Key Words |
| Adsorption, Anion Competition, Fluoride, pH, Thermal treatment, Waste pig bone |
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