Biosorption characteristics of Cadmium(II) onto Scolymus hispanicus L. as low-cost natural biosorbent

This work reports the results of the study of Cadmium (II) removal from aqueous solution by the natural, plentiful and low-cost biosorbent Scolymus hispanicus L. using batch biosorption technique. The biosorption studies were carried out as a function of average biosorbent particle size, pH, biosorbent dosage, contact time, initial metal concentration and temperature. The percentage of biosorption increases with an increase in the biosorbent dosage and the decrease of particle size. The equilibrium metal uptake was increased with an increase in the initial concentration. The maximum biosorption occurred at pH 6.5. Biosorption kinetic data were properly fitted with the pseudo-second-order kinetic model. Equilibrium data were well interpreted by Langmuir model with maximum biosorption capacity of 54.05 mg g(-1). The biosorption is not temperature dependent. The FT-IR spectroscopic analysis of unloaded and Cadmium(II)-loaded Scolymus hispanicus L confirmed that the functional groups on the biosorbent surface were involved in biosorption. (C) 2010 Elsevier B.V. All rights reserved.