Kinetics And Equilibrium Studies Of Fluoride Adsorption On Laterite And Kaolinite: Comparative Studies

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Authors

  • Ndi K. S. Water Treatment and Filtration Research (Chem. Eng.) Group, Department of Process Engineering, ENSAI, University of Ngaoundere, P.O. Box 455, Ngaoundere, Cameroon
  • Kofa . . Higher Institute of Sahel (ISS), University of Maroua, Cameroon
  • G. P., Metiotsop Water Treatment and Filtration Research (Chem. Eng.) Group, Department of Process Engineering, ENSAI, University of Ngaoundere, P.O. Box 455, Ngaoundere, Cameroon
  • AMBA E. V. Water Treatment and Filtration Research (Chem. Eng.) Group, Department of Process Engineering, ENSAI, University of Ngaoundere, P.O. Box 455, Ngaoundere, Cameroon
  • Kayem G. J. Water Treatment and Filtration Research (Chem. Eng.) Group, Department of Process Engineering, ENSAI, University of Ngaoundere, P.O. Box 455, Ngaoundere, Cameroon
September 9, 2015

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The presence of a small amount of fluoride in drinking water is beneficial to human health but a high amount (>1,5 mg/L) has adverse effects. Laterite from Ngaoundere (Cameroon) was testedas a potential adsorbent for removing excess fluoride, and compared with kaolinite. Experiments were carried out by Jar test at room temperature (24 + 2°C), and the removal efficiencies of these materials studied with respect to time (0 - 180min),  stirring speed (60, 160 and 260 rpm), pH (4 - 10), adsorbent dose (1 – 10 g/L). Results showed that adsorption equilibrium is attained in 60 min and kinetics follows a pseudo-second-order model for both adsorbents used. At different pH and stirring speeds, laterite was better than kaolinite in retaining fluoride. The highest fluoride removal by both adsorbents was obtained at pH 4 – 5. Best adsorption fits were obtained with the Langmuir and Redlich–Peterson isotherms. Upon calcination of Laterite at 550 °C, fluoride adsorption increased up to 50%, showing that heat treatment can be used to improve fluoride adsorption by laterite.

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