Simultaneous biosorption of chromium(VI) and copper(II) on Rhizopus arrhizus in packed column reactor: Application of the competitive Freundlich model

The simultaneous biosorption of Cr(VI) and Cu(II) on free Rhizopus arrhizus in a packed column operated in the continuous mode was investigated and co mpared to the single metal ion situation. The breakthrough curves were meas ured as a function of feed flow rate, feed pH, and different combinations o f metal ion concentrations in the feed solutions. Column competitive biosor ption data were evaluated in terms of the maximum (equilibrium) capacity of the column, the amount of metal loading on the R. arrhizus surface, the ad sorption yield, and the total adsorption yield. In the single-ion situation the adsorption isotherms were developed for optimum conditions, and it was seen that the adsorption equilibrium data fit the noncompetitive Freundlic h model. For the multicomponent adsorption equilibrium the competitive adso rption isotherms were also developed. The competitive Freundlich model for binary metal mixtures represented most the column adsorption equilibrium da ta of Cr(VI) and Cu(II) on R. arrhizus satisfactorily.