Adsorptive Removal of Pb(II), Cu(II) and Cd(II) Ions onto Rubus ellipticus as Low-Cost Biosorbent

Abstract

In the present study, removal efficiency (%) of Rubus ellipticus leaves (REL) as an adsorbent for the removal of Pb(II), Cu(II) and Cd(II) ions was investigated. Different parameters i.e., pH, contact time, temperature, adsorbent dose and initial metal ion concentration were investigated to obtain the optimum adsorption efficiency. At pH 4, a maximum adsorption was 84.6, 80.2 and 74.5 % for Pb(II), Cu(II) and Cd(II) ions, respectively. The maximum adsorption of all the three metal ions obtained at contact time (75 min), initial metal ion concentration (10 mg/L), temperature (25 ºC) and adsorbent dose (5.0 g). The equilibrium adsorption of Pb(II), Cu(II) and Cd(II) ions at different temperature was described by Langmuir, Freundlich and Temkin isotherms. The equilibrium data fitted well the Langmuir adsorption isotherm. Thermodynamic parameters like Gibb′s free energy (ΔGº), enthalpy (ΔHº) and entropy (ΔSº) were also calculated. The calculated parameters indicated that adsorption of Pb(II), Cu(II) and Cd(II) ions onto Rubus ellipticus leaves (REL) was spontaneous (ΔGº < 0), endothermic (ΔGº > 0). The feasibility of the process was evident from the positive value of ΔSº.