Removal of fluoride ions from aqueous solution by conducting polypyrrole

Conducting polypyrrole was found to possess potential efficiency to remove fluoride ions from aqueous solutions. The amount of fluoride ions removed per unit mass of the adsorbent, at 30 °C from 10 mg/L fluoride ion solution, was estimated to be 6.37 mg/g. Batch sorption studies have been carried out to determine the effect of initial concentration of the sorbate, agitation time, adsorbent dose, pH, co-ions and temperature on the removal of fluoride by polypyrrole. The sorptive removal was found to be strongly pH and temperature dependent. The experimental data fitted well to the Freundlich and Dubinin-Radushkevick (D-R) isotherms. Thermodynamic parameters such as ΔH0, ΔS0 and ΔG0 were calculated indicating that the adsorption process was spontaneous and exothermic. FT-IR spectral studies suggested that the mechanism of fluoride ions removal follow chemisorption.