| Abstract |
| This study was carried out to investigate the adsorption characteristics of thermally treated dolomite. Dolomite was thermally treated at different temperature (100-950 ℃) and dolomite thermally treated at 900°C (D900) was found to have the highest adsorption capacity for phosphate. D900 showed 12 times higher phosphate adsorption than untreated dolomite. The contents of CaO obtained from X-ray fluorescence analysis did not show significant difference of chemical composition depending on thermal temperature. The specific surface area of D900 was larger than other adsorbents. The time to reach equilibrium for phosphate adsorption onto D900 was 3 hr at low initial concentration (100 mg/L) but 7 days at high concentration (1,000 mg/L). The equilibrium adsorption results were fitted well with both Langmuir and Freundlich models, and low 1/n value indicated that strong adsorption between phosphate and the surface of D900. Thermodynamic analysis showed that the phosphate adsorption onto D900 is endothermic and nonspontaneous reaction. Experiments were carried out under different pH and the presence of competitive anions. As the pH of the solution increased from pH 3 to pH 11, the amount of phosphate adsorption was decreased. The presence of NO3 -, SO4 2-, and HCO3 - decreased phosphate adsorption and its influence follows the order: HCO3 - > SO4 2- > NO3 -. P adsorbed on the surface of D900 was mainly present as residual form. |
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| Key Words |
| Dolomite, Thermal treatment, Phosphate adsorption, pH, Anion Competition, P fractions |
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