Optimization of Cadmium, Zinc and Copper biosorption in an aqueous solution by Saccharomyces cerevisiae

Optimization of Cd (II), Zn (II) and Cu (II) biosorption from contaminated water were performed as function of parameters (pH, contact time, initial metal ions concentration and yeast dose). The experimental results showed that the highest equilibrium adsorption capacity at the optimum pH were 8.5 for Cd (II) and 6 for Zn (II) and 6 for Cu (II). Optimum pH values were carried out to evaluate other parameters. Results demonstrate that removal efficiency increased with increased contact time for the three metal ions. Results indicated that removal efficiency increased with increased yeast dose up to 2 g/ 100ml, and removal efficiency decreased with increased yeast dose from 2.2 g/100ml to 4 g/100ml. The results also showed that increasing removal efficiency from 1 to 20 mg/L concentration for the three metal ions and the removal efficiency decreasing with increasing initial concentration from 25 to 50 mg/L. It is evident that the highest removal efficiency for Cd (II) ion compared to Zn (II) and Cu (II). This study revealed that use of baker’s yeast is suitable for removal of these ions from contaminated water in order Cd > Zn > Cu at these conditions. The negative values of the standard free energy change (∆G) indicate spontaneous nature of the process. Competitive biosorption of (Zn and Cu) ions was investigated in terms of sorption quantity. The amount of Cu metal ion adsorbed onto unit weight of biosorbent (qe) decreased with increasing the competing metal ion (Zn), in contrast, the amount of Zn ion adsorbed onto unit weight of yeast has been increased with increasing the competing metal ion (Cu). The binding capacity for Zn (II) is more than for Cu (II). Ion exchange is probably one of the main mechanism during adsorptive process. [Salem M. Hamza, Hanan F. Ahmed Ehab A. M., Mohammad F. M. Optimization of Cadmium, Zinc and Copper biosorption in an aqueous solution by Saccharomyces cerevisiae. Journal of American Science 2010;6(12):597-604]. (ISSN: 1545-1003). http://www.americanscience.org.