Removal of fluoride from aqueous solution using fired clay soil pillared with tea leaf ash components

Abstract

This study reports on the adsorption of fluoride ion from aqueous solutions by using fired clay soil, pillared with tea leave ash components. The potential of low cost material fired clay soil and fired clay soil pillared with tea leave ash components for fluoride removal from aqueous solution was evaluated by using fluoride ion selective electrode. Pillaring of clay soil with tea leave ash was done by thoroughly mixing fifteen gram of tea leave ash and three hundred gram of clay soil using distilled water and it was aged for 96 hours until it was dried. Untreated clay soil and clay soil pillared with tea leave ash components were fired in an electrical furnace at 570 oC for 3 hrs. Batch adsorption experiments were carried out and the effects of pH, contact time, initial adsorbate concentration, adsorbent dose and temperature of the solution were investigated. Adsorption of fluoride by fired clay soil and fired clay soil pillared with tea leave ash was observed to sharply increase from pH 4 to 7 then decreased. The adsorption of fluoride was observed to increase with initial concentration. The fluoride adsorption process was better represented by the Freundlich isotherm model than Langmuir, with correlation coefficient (r2) of 0.930 and 0.998 for fired clay soil and fired clay soil pillared with tea leave ash components respectively. The maximum adsorption efficiencies obtained were 75% for fired clay soil and 90% for fired clay soil pillared with tea leave ash components at pH 7 for both adsorbents. The Kinetic of fluoride adsorption followed the pseudo-second-order kinetic model as determined by stronger correlation (r2 0.946 and 0.991) for fired clay soil and fired clay soil pillared with tea leave ash components respectively and higher agreement between and . The maximum adsorption capacity obtained was 0.913 mg/g for fired clay soil and 2.746 mg/g for fired clay soil pillared with tea leave ash components. It can be concluded that fired clay soil pillared with tea leave ash is a good and cheap adsorbent with high potential for the adsorption and removal of fluoride from fluoride contaminated water and could therefore serve as effective and efficient adsorbent for treatment of drinking waters in terms of high adsorption capacity.