Studies on fluoride adsorption of iron-impregnated granular ceramics from aqueous solution

This study evaluated the effectiveness of iron-impregnated granular ceramics in removing fluoride from aqueous solution. Kanuma mud, zeolite, starch and FeSO4·7H2O/Fe2O3 mixed to prepare granular ceramic at room temperature by granulation procedure with the mass ratio of 4:3:2:1. Both the adsorbents were characterized by SEM, EDS and BET surface area. The various experimental parameters investigated for fluoride adsorption from aqueous solution were: contact time, initial pH, initial fluoride concentration and temperature. The GC (FeSO4·7H2O) is more effective for fluoride removal than GC (Fe2O3) in adsorption capacity. The optimum pH for fluoride removal on GC (FeSO4·7H2O) and GC (Fe2O3) was 7.0 and 4.0, respectively. The experimental data fitted reasonably well to both Langmuir and Freundlich isotherm models for these two adsorbents. The two adsorption process followed pseudo-second-order kinetics with intra-particle diffusion as the rate determining step. The calculated thermodynamic parameters showed that both of the adsorption processes were thermodynamically favorable, spontaneous and endothermic in nature.