Adsorption of Mixtures of Toxic Metal Ions Using Non-viable Cells of Saccharomyces cerevisiae

The use of waste biomaterial for the adsorption of heavy metal ions is an economically appealing alternative to conventional metal ion removal methods. In the present work, S. cerevisiae biomass has been shown to be capable of the simultaneous removal of more than 98% of Pb(II) ions, 60% of Zn(II) ions and up to 55% of Cu(II) ions from aqueous solutions in the 10-50 mg/l concentration range. Model equations describing the removal efficiency of each metal ion were determined using Response Surface Methodology (RSM) with respect to operating conditions such as pH, initial metal ion concentration and biomass dosage. Characterization of the metal ion-biomass interactions responsible for biosorption was studied employing zeta potential measurements, BET, FT-IR and EDX techniques; these indicated that the uptake of metal ions by non-living yeast was a surface adsorption phenomenon. The results proved the involvement of an ion-exchange mechanism between the adsorbing metal ions and the cell walls. In the presence of the complete range of metal ions studied, yeast cells were more selective towards Pb(II) ions.