Fixed bed adsorption of fluoride by Artocarpus hirsutus based adsorbent

Abstract The permissible limit of fluoride level in ground water is 1.5 mg/L and if it is exceeded, it causes fluorosis and about 3.2% people have been affected by this disease worldwide. The potential of ferric hydroxide and activated alumina impregnated sawdust (SFAA) for fluoride removal from groundwater by fixed bed study is presented. The dynamic removal of fluoride in the packed bed column has been studied as a function of particle size, concentration and flow rate. The adsorption of fluoride by the adsorbent increased with decrease in particle size of SFAA, flow rate and initial fluoride concentration. The studies show that SFAA is efficient at flow rate of 0.5 mL/min for initial fluoride concentration of 12 mg/L and average particle size of 0.082 mm. To predict the breakthrough and to determine the column parameters for process design, four breakthrough models viz., Thomas, Yoon-Nelson, Bohart-Adam and Clark model were applied. Among these models, the models proposed by Thomas and Clark give the most satisfactory fit, which indicates the adsorption behaviour follows second order reversible reaction kinetics. Logistic model also tested for the non linear regression approach.