ADSORPTION OF FLUORIDE FROM AQUEOUS SOLUTIONS BY A CHITOSAN/ZEOLITE COMPOSITE

This study examined the feasibility of removing the fluoride ion (F-) from aqueous solutions using a chitosan/zeolite composite. The effects of F- concentration, chitosan/zeolite composite dosage, and contact time on the adsorption of F- by chitosan/zeolite composite at a constant temperature (30 degrees C) and pH (pH = 7) were also evaluated. Pseudo-first and second-order, intraparticle diffusion, and Bangham models were adopted to evaluate the experimental data and thereby elucidate the kinetic adsorption process. The adsorption percentage of F- increased as the chitosan/zeolite composite dosage and the contact time increased. Conversely, the adsorption percentage decreased as the F- concentration increased. The pseudo-second-order model best represented the adsorption kinetics. Based on the regressions of the intraparticle diffusion and Bangham models, the experimental data suggest that the adsorption of F- on to the chitosan/zeolite composite involved intraparticle diffusion, but that was not the only rate-controlling step.