Comparison of copper(II) biosorptive properties of live and treated Candida sp.

Biosorption of copper(II) ions from aqueous solutions was studied to compar e the binding capacities of untreated (live) or treated (dried, autoclaved, perchloric acid (HClO4)-washed, ethanol-treated, formaldehyde-treated) Can dida sp. Due to the ion exchange nature of metal biosorption, copper(II) up take was strongly affected by the solution pH and optimum adsorption pH val ue was determined as 5.0 for all the live and treated Candida sp. At the op timal conditions, metal ion uptake increased with increasing initial copper (Il) concentration up to 300 mg l(-1) for all the biomass types. It is foun d that all the treatment methods used to kill the yeast (except for formald ehyde treatment) increased the copper(II) biosorption capacity of Candida c ells. The results also indicated that copper(II) biosorption by live, autoc laved and formaldehyde-treated yeasts was consisted of an initial, rapid su rface binding of copper(II) followed by a second, slower intracellular upta ke of copper(II), but copper(II) uptake by the other treated yeasts took pl ace only via surface binding. Both the Freundlich and Langmuir adsorption m odels were suitable for describing the short-term biosorption of copper(II) by all the untreated and treated Candida.