Removal of heavy metals from aqueous solutions by cercis siliquastrum L.

In this study the ability of Cercis siliquastrum L. leaves for the adsorption of Pb(II), Cu(II) and Ni(II) ions were studied. The effects of different parameters such as contact time of biosorbent and sorbents, pH of metal solution, and initial metal ion concentration on the biosorption were investigated. The maximum sorption of all metals were carried out in pH4. Increasing the initial metal concentration in lower values caused a steep growth in biosorption, which was not observed in higher values. In the optimum sorption condition, the affinity of the leaves to metal ions was in the order of Pb(II)>Cu(II)>Ni(II). The biosorption of the metal ions were studied by Langmuir and Freundlich adsorption isotherm models. It was observed that the data were fitted very well to Langmuir adsorpotion isotherm model. According to the obtained correlation coefficient values, Freundlich model could predict Pb(II) and Cu(II) adsorption adequately but it was not suitable for Ni(II) sorption. Experimental data were exploited for kinetic evaluations related to the sorption process. According to our results, second-order kinetic provided a good description of biosorption for the tested metals with regression correlation coefficients more than 0.9998 for all the sorbate-sorbent systems.