| Popis: |
Batch adsorption studies were carried out to evaluate the Pb 2+ adsorption capacities of three different fired clay soils with different particle size distributions. Adsorption efficiency was observed to increase with an increase in clay content. Adsorption efficiencies of the fired clay soils were also influenced by the firing temperature, the solution’s acidity, initial Pb 2+ concentration, shaking time and adsorbent dose. Adsorption of Pb 2+ by the clay soils was observed to increase linearly from pH 1 to 5 and then remained nearly constant at higher pH values. The adsorption of Pb 2+ was observed to increase sharply with Pb 2+ for the lower initial concentrations (5 to 10 mg/L), while a modest increase in Pb 2+ adsorption was found from 10 to about 50 mg/L, a concentration at which maximum removal was attained. The Langmuir and Freundlich adsorption models were applied to the adsorption data and the Langmuir model represented the adsorption process better than the Freundlich model, with correlation coefficients (R 2 ) ranging from 0.97 to 0.99. The adsorption capacities (qm) calculated from Langmuir for the adsorption of Pb 2+ by S 3F , S 2F and S 1F were found to be 17.3, 15.9, and 11.2 mg/g, respectively. Key words : Adsorption, fired clay soils, isotherm, adsorption kinetics, sand, silt, particle size. |
