Lead removal from aqueous solutions by natural Greek bentonites

Three bentonite samples (B1, B2, B3) from Milos Island, Greece, were investigated by XRD, AAS, DTA-TG, FTIR and specific surface area measurement techniques. A laboratory batch study has been performed to investigate the adsorption characteristics of lead ions (Pb2+) onto natural bentonite samples. The effect of various physicochemical factors that influence adsorption, such as solution pH (2-6), adsorbent dosage (1-10 g L-1), contact time (20-360 min), and initial metal ion concentration (5-150 mg L-1) was studied. A number of available models like the Lagergren pseudo first-order kinetic model, the pseudo second-order kinetic model and intra-particle diffusion were utilized to evaluate the adsorption kinetics. The adsorption of Pb2+ was modelled with the Langmuir, Freundlich and D-R isotherms. The maximum Pb2+ adsorption capacities for B1, B2 and B3 were 85.47 mg g(-1), 73.42 mg g(-1) and 48.66 mg g(-1), respectively.