Removal of lead from aqueous solutions by low cost and waste biosorbents (lemon, bean and artichoke shells).

Simple, fast, effective, low cost and waste biosorbents, lemon, bean and artichoke shells, were used to remove lead (II) ions from aqueous solution. The influence of pH, contact time, temperature and lead (II) concentration of the removal process was investigated. The sufficient contact time was deemed 10 minutes for bean and artichoke shells and 60 minutes for lemon shells for Pb(II) ions. The thermodynamic parameters, such as standard free energy (ΔG), standard enthalpy (ΔH), and standard entropy (ΔS) of the adsorption process were calculated as -5.6786, -5.5758, -3.1488 kJmol for ΔG, -7.2791, -20.285, -9.5561 kJ mol for ΔH, -0.00545, -0.05017, -0.02185 kJ mol K for ΔS, respectively, for lemon, artichoke and bean shells. Maximum adsorption capacities of lead (II) were observed as 61.30 mg g, 88.5 mg g and 62.81 mg g, respectively, for lemon, bean and artichoke shells according to the Freundlich isotherm model at 20 °C. Scanning electron microscope (SEM) and energy-dispersive X-ray detector (EDX) were used to characterize the surface morphology of the adsorbents. Consequently, Pb(II) removal using lemon, bean and artichoke shells would be an effective method for the economic treatment of wastewater.