Equilibrium, kinetics and breakthrough studies for adsorption of fluoride on activated alumina

Contamination of drinking water due to fluoride is a severe health hazard problem. Excess of fluoride (>1.5 mg/l) in drinking water is harmful to the human health. Various treatment technologies for removing fluoride from groundwater have been investigated in the past. Present investigation aims to remove fluoride by activated alumina. Adsorption isotherm has been modeled by Langmuir equation and isotherm constants. The dependence of the adsorption of fluoride on the pH of the solution has been studied to achieve the optimum pH value and a better understanding of the adsorption mechanism. It was found that maximum adsorption takes place at pH value of 7. Breakthrough analysis revealed that early saturation and lower fluoride removal takes place at higher flow rate and at higher concentrations. Predicted simulation results of one-dimensional model for isothermal, axially dispersed fixed bed on the assumption of pore-diffusion rate-control conditions matches with the experimental data in the initial zone of the breakthrough curve, but deviated marginally in the final tailing zone. Bed depth service time (BDST) model was also applied successfully.