The adsorption of fluoride ion from aqueous solution by activated alumina

The adsorption of fluoride ion in aqueous solution by using alumina was studied in this research. The experimental results indicated that the removal efficiency was influenced significantly by solution pH and the optimum operating pH was found to be in the range of 5 to 7. For neutral and acidic solutions, the adsorption capacities of fluoride by alumina was interfered by the presence of sulfate. The Langmuir and Freundlich isotherms can well describe the equilibrium behaviors of the adsorption processes. The experimentally determined low values of activation energy indicate nonspecific adsorption is the predominant mechanism. The surface reaction-limiting batch kinetic model can adequately describe the removal behaviors of fluoride ion by alumina adsorption in the batch system.