PRELIMINARY INVESTIGATIONS ON THE DEFLUORIDATION OF WATER USING FIREDCLAY CHIPS

The adsorption of fluoride ions on ground fired clay pot has been inve stigated. The maximum efficiency of the adsorbent for defluoridating 1 -2 litres of water was found to be 200 mg fluoride kg(-1) adsorbent. T he investigation showed that 5-20 mg l(-1) fluoride, from 1 litre of w ater, could be reduced to less than 1.5 mg l(-1) using 120-240 g of th e adsorbing medium. The effects of the dose of the medium, the pH, the contact time and the initial fluoride content were studied in relatio n to defluoridation efficiency. Comparison of fluoride removal capacit y of the adsorbent was also made with those of fired brick, clay soil and red ash. The latter exhibited practically no adsorption. A packed column of the same ground clay pot was saturated with 285 mg fluoride kg(-1) of adsorbent when 20 litres of water containing 10 mg l(-1) F w as allowed to pass through it. This column defluoridated 6 litres of t ap water containing 10 ppm F- to below 1.5 mg l(-1). Copyright (C) 199 6 Published by Elsevier Science Ltd