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

摘要

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 Cr~(3+),Cu~(2+)and Cd~(2+)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.