Adsorption of fluoride was done from its aqueous solution by using microwave assisted activated carbon. The activated carbon was prepared by carbonization of Acacia Auriculiformis scrap wood char followed by microwave heating. A batch study on fluoride sorption was carried out at various experimental conditions, including different pH, initial fluoride concentrations, adsorbent concentrations, competitive anion chloride and different temperatures. Fluoride adsorption was found to be pH dependent and the maximum removal of fluoride was obtained at pH of 4.4. On the other hand, the fluoride adsorption was reduced in the presence of chloride ions. The percentage removal of fluoride was found to be increased with increase in temperature and adsorbent dose and a maximum removal of 97.2% was obtained with an adsorbent dose of 2 g/l. On the other hand, the adsorption of fluoride was also increased with decrease in particle size and the maximum removal occurred at a particle size of 58 μm. In order to investigate the mechanism of fluoride removal, various adsorption isotherms such as Langmuir, Freundlich, Tempkin and Herkin-Jura were fitted at 293, 303, and 323 K . The experimental data revealed that the Langmuir isotherm gave more satisfactory fit for fluoride removal. The monolayer adsorption capacity according to Langmuir isotherm was found to be 19.92 mg/g. The adsorption process was observed to follow a pseudo-second-order kinetic model. Thermodynamic parameters were also determined and change in enthalpy and entropy were found to be 6.094 kJ/mol and 19.022 J/mol-K respectively.
