Determination and modelling of effects of pH on peat biosorption of chromium, copper and cadmium

Adsorption of metals onto biological materials, including peat, or biosorption is well-recognised as a potential alternative to conventional wastewater treatments processes. In this work, biosorption of Cr3+, Cu2+ and Cd2+ onto peat in batch systems was investigated in the pH range 2-7. The order of maximum uptake was Cr > Cu > Cd. Both H+ ion competition and pH-dependent speciation affected uptake levels. For Cr and Cu optimum pH was ca. 4, while for Cd greatest uptake occurred at pH 7. Of three selected multi-component sorption models an extended Langmuir model, which is based on the direct competition of metal ions and protons for biosorbent sites, exhibited best fit. Three-dimensional sorption surfaces were generated which described the cation uptake as a function of both final metal and final H+ concentrations. (C) 2003 Elsevier Science B.V. All rights reserved.