Adsorption of Lead(II) from Aqueous Solution by Using Leaves of Date Trees As an Adsorbent

Abstract

The efficiency of date tree leaves as a low cost adsorbent for removing lead ions from aqueous solution has been investigated in this paper. Batch experiments were conducted to study the effects of the main parameters such as contact time, initial concentration of Pb(II), adsorbent dose, solution pH, agitation speed, ionic strength, and temperature on the adsorption of Pb(II) by date tree leaves. The maximum removal of lead(II) is found to be 94 % at pH 5.8, initial Pb(II) concentration of 10 mg·L−1, adsorbent dose of 1 g·L−1, agitation speed of 200 rpm, ionic strength of 0.005 M, and temperature of 25 °C. Dynamics of the adsorption process were studied, and the values of rate constants of pseudofirst-order and pseudosecond-order were calculated. Equilibrium isotherms for the adsorption of Pb(II) were analyzed by the Langmuir, Freundlich, and Temkin isotherm models. The Temkin isotherm model was found to represent better the data of Pb(II) sorption onto date tree leaves. Different thermodynamic parameters, namely, changes in standard Gibbs energy, enthalpy, and entropy, were also evaluated from the temperature dependence, and the results suggest that the adsorption reaction is spontaneous and endothermic in nature.