Bleaching powder: A versatile adsorbent for the removal of fluoride from aqueous solution

The objective of this study was to investigate the potential of bleaching powder for the removal of excess fluoride from aqueous solution. The influence of various operational parameters viz. effect of adsorbent dose, pH, initial concentration, interfering ions and contact time were studied by a series of batch adsorption experiments. It was noticed that the adsorbent showed reasonably significant fluoride removal in the mid or high pH region. The presence of sulphate, nitrate and chloride ions to some extent was found to affect the fluoride removal, indicating that these ions may compete with each other for the sorption of fluoride. The equilibrium adsorption data were fitted well for the Langmuir model and the adsorption capacities were worked out. The rate of adsorption was initially rapid and the maximum level was attained within 60 min. Comparative studies for fluoride removal in synthetic as well as field water showed relatively higher fluoride removal in synthetic water. From these studies, it may be concluded that bleaching powder is an efficient and economical adsorbent for fluoride removal from aqueous solutions.