Determination of the biosorption heats of heavy metal ions on Zoogloea ramigera and Rhizopus arrhizus

The biosorption of Fe(III), Cr(VI), Pb(II), Cu(II) and Ni(II) ions on Zoogl oea ramigera (activated sludge bacterium) and Rhizopus arrhizus (filamentou s fungus) has been studied as a function of initial metal ion concentration and temperature. The applicability of the Langmuir model for each metal-mi croorganism system has been tested at different temperatures. The enthalpy change for the biosorption process has been evaluated by using the Langmuir constant b, related to the energy of adsorption. Thermodynamic parameters indicate the exothermic nature of Cu(II) and Ni(II) biosorption on both mic roorganisms. Fe(III), Cr(VI) and Pb(IT) biosorption is determined to be an endothermic process since increased binding occurs as the temperature is in creased in the range 15-45 degrees C. (C) 2000 Elsevier Science S.A. All ri ghts reserved.