Fluoride Removal from Aqueous Solutions By Adsorption with Coal Ash

Abstract

Dynamic adsorption studies were performed to study the suitability of coal ash to remediate fluoride-contaminated water. A series of experiments were conducted with aqueous solutions containing 2.5, 5, 10, 50 and100 mgF-/ℓ at 29 oC in a column packed with 500g of coal ash. The flow rate through the bed was 2 mℓ/hr. The effects of contact time, initial adsorbate concentration and sorbent particle size range on fluoride removal efficiency were studied. Better removal efficiencies were obtained with lower particle size ranges. The F- concentration inthe effluent gradually decreased reaching 0 mg/ ℓ after 96-168 hours depending on the initial adsorbate concentration. The kinetic results showed that defluorination follows first order kinetics. An empirical formula was proposed to describe the relationship between the fluoride removal efficiency and the dependent operating variables with 95% confidence level.

Keywords

• fluoride removal
• adsorption
• coal ash
• statistical analysis