Biosorption of Ni(ii) and Pb(ii) by Phanerochaete chrysosporium from a binary metal system - Kinetics

The biosorption kinetics of Ni(II) and Pb(II) by the resting cells of a lig nolytic white-rot fungus, Phanerochaete chrysosporium. from a binary metal system were investigated. Kinetic studies revealed that biosorption takes p lace in two stages: a rapid surface adsorption, within the first 30 min, an d a slow intracellular diffusion till the end of the 3 h contact time. In t he first minutes of contact solution pH decreased sharply, parallel to the fast metal uptake, probably because of the protons released by the biosorbe nt. As sorption equilibrium was reached, solution pH also reached an equili brium level. Metal biosorption capacities increased as the initial metal co ncentrations (C-i) increased. independent of initial pH (pH(i)) and general ly the metal with higher C-i had a higher uptake capacity. The results also show that some portion of the metal. ions sorbed by P. chrysosporium was r eadily released to solution with a decrease in pH. At equilibrium, the maxi mum total metal uptake of P. chrysosporium was 109.5 mg/g and was reached a t pH(i) 5. Under these circumstances Ni(II) and Pb(II) uptake capacities we re 55.9 mg Ni/g and 53.6 mg Pb/g, respectively.