The adsorption of fluoride ion from aqueous solution by activated alumina

The adsorption of fluoride ion in aqueous solution by using alumina was stu died in this research. The experimental results indicated that the removal efficiency was influenced significantly by solution pH and the optimum oper ating pH was found to be in the range of 5 to 7. For neutral and acidic sol utions, the adsorption capacities of fluoride by alumina was interfered by the presence of sulfate. The Langmuir and Freundlich isotherms can well des cribe the equilibrium behaviors of the adsorption processes. The experiment ally determined low values of activation energy indicate nonspecific adsorp tion is the predominant mechanism. The surface reaction-limiting batch kine tic model can adequately describe the removal behaviors of fluoride ion by alumina adsorption in the batch system.