Chemically activated cotton nut shell carbons (CTNSCs) were prepared by different chemicals and they were used for the removal of fluoride from aqueous solution. Effects of adsorption time

adsorbent dose

pH of the solution

initial concentration of fluoride

and temperature of the solution were studied with equilibrium

ther-modynamics and kinetics of the adsorption process by various CTNSC adsorbents. It showed that the chemically activated CTNSCs can effectively remove fluoride from the solution. The adsorption equilibrium data correlate well with the Freundlich isotherm model. The adsorption of fluoride by the chemically activated CTNSC is spontaneous and endothermic in nature. The pseudo first order

pseudo second order and intra particle diffusion kinetic models were applied to test the experimental data. The pseudo second order kinetic model provided a better correlation of the experimental data in comparison with the pseudo-first-order and intra particle diffusion models. A mechanismof fluoride adsorption associating chemisorption and physisorption processes is presented allowing the discussion of the variations in adsorption behavior between these materials in terms of specific surface area and porosity. These data suggest that chemically activated CTNSCs are promising materials for fluoride sorption.