Ion Exchange Basis for Biosorption and Bioremediation of Heavy Metals

Abstract

An important aspect of mining operations is the extent of sorption of effluent metals to soil and biomass. Of special interest is the partitioning of metal ions in the aqueous-soil-biomass system. The ion exchange relationship of Zn, Cd, Cu, and Pb was found to apply for the metal in the presence of two sorbents: soil with either peat moss, watercress roots, or rye roots. The uptake of Cd from soil by growing rye grass increases with Cd content in the soil, although the per cent uptake is higher for lower amounts. Exchange constants for displacement of protons from limestone soil by Cd decrease by a factor of 10⁵ as pH changes from 4 to 6.6. A linear relationship for log K^H _exvs. pH can be interpreted as Cd binding to weaker acid sites in more basic media. Comparable results were found for peat moss and the alga Vaucheria. These findings are relevant to agricultural hazards posted by heavy metals as well as the possible use of certain crops for bioremediation.

Keywords:

• Ion exchange
• biosorbent
• lead
• cadmium
• copper
• soil

Notes

†Presented in part at the Third International Conference on Minerals Bioprocessing and Biorecovery/Bioremediation in Mining, Big Sky, Montana August 25-30, 1996

Additional information

Notes on contributors

DELANSON R. CRIST

Department of Chemistry, Georgetown University, Washington, DC 20057.