Cadmium removal from aqueous solutions using biosorbent Syzygium cumini leaf powder: Kinetic and equilibrium studies

Syzygium cumini L. leaf powder and Cd(II) loaded samples were characterized using FTIR and SEM techniques. The biosorption of cadmium ions from aqueous solution was studied in a batch adsorption system as a function of pH, contact time, adsorbate, adsorbent, anion and cation concentrations. The biosorption capacities and rates of transfer of cadmium ions onto S. cumini L. were evaluated. The kinetics could be best described by both linear and nonlinear pseudo-second order models. The isothermic data fitted to various models in the order Freundlich>Redlich-Peterson>Langmuir>Temkin. The maximum adsorption capacity of S. cumini L. leaves at room temperature was estimated to be 34.54 mg g(-1). The negative values of Delta G degrees indicated the feasibility of the adsorption process. The endothermic nature was confirmed by the positive value of the enthalpy change (AH degrees=3.7 kJ mol(-1)). The positive value of entropy change (Delta S degrees=16.87 J mol(-1) K-1) depicted internal structural changes during the adsorption process.