Effect factors and adsorption behavior of granular iron-oxide-zeolite in the removal of fluoride from aqueous solution

In this study, a granular iron-oxide-zeolite (GIOZ) was successfully prepared using the uniform hydrolysis method. Effect factors and adsorption behavior of GIOZ were investigated by a series of batch experiments. The effects of adsorbent dosage, contact time, pH, initial concentration and the co-existing ions on the removal of fluoride were studied. In order to study the sorption isotherm, two equilibrium models, the Freundlich and Langmuir isotherms, were analyzed. The result showed that more than 80% removal of fluoride was achieved within 40 min from a 20 g/L solution with pH at 5~6. XRD spectra of adsorbent before and after exposure to fluoride ions suggested that a new chemical bond formed on surface of GIOZ and fluoride was effectively removed by the chemical adsorption. It is concluded that the reclaimed GIOZ can be considered as a feasible and economical adsorbent for fluoride removal.