Development of multimetal binding model and application to binary metal biosorption onto peat biomass.

Biosorption of Cr(3+), Cu(2+) and Cd(2+) from binary metal solutions onto peat in the batch systems was investigated at pH 4. The order of maximum uptake was Cr>or=Cu>Cd and maximum uptake levels of ca. 0.4 mmol/g were observed for chromium and copper while cadmium was taken up to a maximum of ca. 0.2 mmol/g. Co-ion competition resulted in up to 70 percent decrease of primary metal uptake. A novel approach to multicomponent sorption modelling involving regression to the total metal taken up was adopted. Two extended Langmuir-type models were found to exhibit good fit to the experimental data. Using the simpler model of these, three-dimensional sorption surfaces were generated which describe the metal uptake as a function of equilibrium concentrations of both metals. These methods allow prediction of metal uptakes over a continuum of concentrations of both metals in binary systems.