Biosorption of Cu(II), Zn(II) and Pb(II) ions onto Dicliptera bupleuroides leaves (DBL) in a batch system with respect to adsorbent dose, contact time, temperature, pH and initial metal ion concentration was investigated. Langmuir, Freundlich and Temkin isotherm model were applied to describe the equilibrium data. Langmuir isotherm model provided a better fit to the experimental data than the Freundlich and Temkin isotherm. The adsorption capacity is 2.55 mg/g, 1.06 mg/g, and 1.76 mg/g for Cu(II), Zn(II) and Pb(II) respectively. The optimum adsorption conditions obtained were at contact time 75 min, pH 5, initial metal ion concentration 10 mg/L, temperature 45 oC for Cu(II) and 30 oC for Zn(II) and Pb(II) and adsorbent dose 2.5 g. Thermodynamic parameters indicated that the adsorption reactions were spontaneous (ΔGo<0), feasible and exothermic (ΔHo<0) .
Adsorption, Heavy metals, Dicliptera bupleuroides leaves, Isotherms, thermodynamic Parameters