Process Engineering

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Browsing Process Engineering by Author "Admasu, Arega"

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    Performance of Mg and Al mixed Oxides Derived From Hydrotalcite For Removal of Fluoride from A Solution
    (Addis Ababa University, 2015-10) Admasu, Arega; Beteley, Tekola (PhD)
    Exploiting efficient and affordable treatment technology for fluoride removal via adsorption is highly desirable. In this study, calcinedhydrotalcites with different Mg/Al molar ratios were prepared. Layered double hydroxides calcined at 450 have been shown to recover their original layered structure in the presence of appropriate anions which may enhance its adsorption capacity. Uptake of fluoride ion from aqueous solution by CHT was investigated by batch experiments. The response surface methodology was applied to optimize the adsorption capacity by employing a factorial design. The optimal pH, initial fluoride concentration and Mg/Al molar ratio in CHT were found to be 6.0, 5mg/L and 2 respectively for the maximum percentage adsorption of 94.4%.The equilibrium isotherm showed that the uptake of fluoride ion by CHT was consistent with the Langmuir and Freundlich equations and that the Langmuir model gave a better fit to the experimental data than the Freundlich model. The maximum uptake capacity of CHT for fluoride ion by the Langmuir isotherm model was estimated to be 0.4762 mg/g. The influence of varying pH of solution, initial fluoride concentration and Mg/Al molar ratio in the structure of CHT on the kinetics of fluoride removal has also been explored. Kinetic models were used to fit the experimental data, and it was found that the pseudo-second-order kinetics model could be used to describe the uptake process satisfactorily. The present work demonstrates that calcinedhydrotalcites may be promising adsorbents for effective removal of fluorine from water resources.