죽탄을 이용한 불소이온 제거에 관한 연구

Abstract

In recent, The fluorine fixed quantity in the drinking water is very small amount very with 0.5 ~1.0 mg/L and the symptom of existence at the time of fluorine composure symptoms appears at 1 ~ 2 mg/L consistency. A variety of defluoridating agents such as activated alumina, lime, zeolite, carbon, clay minerals, fly-ash and spent catalyst have been used for the reduction of the fluoride content of potable water. Activated carbon prepared from waste materials such as coconut, sawdust and coffee waste, either by direct carbonisation of by sulfuric aced treatment, have also been evaluated after aluminium sulfate impregnation. However, the removal of fluoride from the spiked water samples using these methods was found to be about 80% and their removal capacity decreased sharply in saline conditions. Overall these were found to be unsuitable due to their poor attritional characteristics and low capacity for fluoride removal. The fluorine removal research for old time was researched about the water where becomes the materials of the drinking water with like this reason and was come. In this paper, the adsorption behavior of nitrate anion and mechanism in aqueous solution investigated using FeCl3-dipped charcoal(FT), HCl-treated charcoal(AT) and FeCl3-HCl treated charcoal(FTAT). Also, The influence of various parameters such as F- concentration, adsorbent dose, repeated adsorption and temperature has been studied. The removal efficiency of fluoride was increased with increasing of dosage of adsorbents. The F- removal was not affected by the pH under the experiment range of pH. The degree of removal was found to be dependent on temperature and it is increased as the temperature decrease. It was found that the obtained charcoal had the ability to absorb nitrate and fluoride anion but not sulfate and phosphate anions. The adsorbents was regenerated using KCl solution, and recovery was about 76.6% at 1 M of KCl. Batch adsorption studies have shown that the adsorption reaction can be described by the second-order reversible reaction. The process of uptake obeys both Langmuir and Freundlich isotherms. The thermodynamic parameters were also calculated to elucidate the adsorption mechanism. The values of △Ho and △So were obtained from the slope and intercept of the van't Hoff plots of in b vs 1/T. The negative value of the △Ho suggests the exothernic nature of adsorption. The negative values of △Go indicates the spontaneous nature of adsorption of F- by the adsorbents(AT and FTAT). The negative value of △So shows that the freedom of molecules of F- is more restricted in the charcoal particles(AT and FTAT) than in solution. The plots of the in C vs 1/T at different surface loading were found to be linear and △Hx values were calculated from the slope of the curves. The value of the △Hx was almost constant and was independent of surface loadings. The order of magnitude of the value indicates a weakend chemical mechanism for the adsorption of F- on to AT and FT.