Removal of Fluoride from Contaminated Drinking Water using Unmodified and Aluminium Hydroxide Impregnated Blue Lime Stone Waste

The adsorption of fluoride on lime stone (LS) and aluminium hydroxide impregnated lime stone (AlLS) was investigated using a batch adsorption technique. A series of experiments were under taken in an agitated batch adsorber to assess the effect of the system variables such as solution pH, dye concentration and temperature. Removal of fluoride was observed to be the most effective at pH 8. The langmuir and Freundlich isotherm models were applied to the equilibrium data. The results showed that the Freundlich equation fits better than the Langmuir equation. The maximum sorption capacities for the LS and AlLS adsorbents were found to be 43.10mg/g and AlLS 84.03mg/g respectively. The FTIR studies indicate that the adsorption of fluoride is physiorption. The adsorption of fluoride onto AlLS proceeds according to a pseudo-first-order model. The results reveal that the LS and AlLS can be economical for the removal of fluoride compared to many other expensive adsorbents.