Removal of Fluoride from drinking water by an activated Bentonite: application to a drinking Tunisian water

Abstract

Many regions in the South of Tunisia suffer from the existence of fluoride as considerable amounts (3 to 4.5 mg/L)in water resources. A Tunisian Bentonite was used for this aim. This natural and save absorbant was purified then activated. A Fe-Ben, was obtained, which shows a good potential as a cheap and efficient adsorbent for anionic micro pollutants removal from aqueous media. The modified bentonite was characterized by XRD and FTIR. The effect of pH, temperature, clay/fluoride ratio, equilibrium time and competitive ions on the adsorption of fluoride ions by batch process was studied. The obtained results revealed thata fluoride removal efficiency higher than 80%was obtained in the pH range 2- 7. The equilibrium exhibits 40 min to be reached at room temperature. Kinetics data fitted pseudo-second-order model. Batch adsorption data was better described by Langmuir isotherm model than Freundlich isotherm model. The defloridation of a Tunisian drinking water containing considerable amounts of fluoride has shown prospective results at room temperature and in neutral pH.