Assessment of iron oxide and local cement clay as potential fluoride adsorbents

Health problem from fluoride contaminated water is more acute in rural and small urban communities. Defluoridation of low contaminated water by inexpensive adsorbents is a substantial practice worldwide. In the study, low-cost sorbents have been investigated as replacements for current costly methods of removing the excess fluoride from water below the certain concentration. The adsorption capacity of iron oxide and cement clay in fluoride removal was investigated by the batch method. The equilibrium time was attained in 3 h and 2 h for iron oxide and cement clay, respectively. Optimum adsorbent dosage was found to be 5 g/dm³. Initial fluoride concentrations for the adsorption studies were 1.24 and 12.2 mg/dm³. Fluoride adsorption isotherm fitted well the Freundlich isotherm with the coefficient of determination >0.99 for both adsorbents. The fluoride adsorption capacity of iron oxide was found higher than that of cement clay due to the high surface area and charge of iron oxide. How-ever both substances can reduce F– contamination below the acceptable limits of 1.5 mg/dm³ for less contaminated water.