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Abstract
The kinetics of Pb sorption were investigated on clay (silty clay, Torrifluvents), CaCO3‐rich (sandy clay, Calciorthids), and sandy (sandy loam, Quartzipasmments) soils at two different temperatures. Equilibrium in Pb sorption was attained in 2, 12, and 24 h for CaCO3‐rich, sandy, and clay soils, respectively. The kinetics of Pb sorption were evaluated using Elovich, modified Freundlich, parabolic diffusion, and first‐order equations. The first‐order equation adequately described the kinetics of Pb sorption for all the soils, temperatures, and initial concentrations used. The choice of the first‐order equation among the others investigated was based on the lower standard error of estimate (SE) obtained and on the more realistic assumptions of the equation. The sorption rate coefficient (k a) values, at 298 K, ranged from 1.46 × 10‐3 to 6.58 × 10‐3 min‐1 in the sandy soil, from 2.42 × 10‐3 to 11.72 × 10‐3 min‐1 in the clay soil, and from 33.16 × 10‐3 to 58.42 × 10‐3 min‐1 in the CaCO3‐rich soil. The higher k a values of the CaCO3‐rich soil are attributed to its higher calcium carbonate content. The k a values for all the soils studied increased with increasing temperature.