Biosorption of Pb(II) and Cd(II) Ions from Aqueous Solution by Chemically Modified Syzygium cumini Leaves and its Equilibrium, Kinetic and Thermodynamic Studies

Abstract

The removal of Pb (II) and Cd (II) ions from aqueous solution by a novel low-cost biosorbent; chemically modified Syzygium cumini leaves (CMSCL) was studied. The effects of biomass dosage, pH, concentration, temperature and contact time were investigated. Characterization of CMSCL was carried out by FT-IR spectroscopy, pore size, and surface area analyzer. The maximum biosorption capability of CMSCL for Pb (II) and Cd (II) ions was 104 and 50 mg/g at optimum conditions of pH 6 and 7, biomass dosage of 5 g/L, contact time of 120 and 90 min and temperature of 50 and 40 0C, respectively. The experimental data was analyzed using pseudo-first order and pseudo-second order kinetics models. The biosorption of Pb (II) and Cd (II) followed pseudo-second order model. Langmuir, Freundlich and Temkin adsorption isotherm models were applied to explain the removal of heavy metal ions by CMSCL biosorbent. Langmuir isotherm model fitted better than other isotherm models. Thermodynamics parameters such as �H0, �G0 and �S0 showed that the biosorption of Pb (II) and Cd (II) ions onto CMSCL was spontaneous, exothermic and feasible under examined conditions. The occurrence of various functional groups and change in the absorption frequency after metal uptake indicates that complexation was the main mechanism involved in the process of biosorption. Based on the present investigation, it was proved that CMSCL is an effective, alternative and economical biosorbent for the removal of Pb (II) and Cd (II) ions. Keywords: