CALCIUM AND MAGNESIUM INTERFERENCE STUDIES FOR THE BINDING OF HEAVY METAL IONS IN SOLUTION BY MEDICAGO SATIVA (ALFALFA)

J.L. Gardea-Torresdey1,3, K.J. Tiemann1, J.H. Gonzalez1, J.A. Henning2, and M.S. Townsend2, 1Department of Chemistry, The University of Texas at El Paso, El Paso, TX, 79968, Phone: 915-747-5359, FAX: 915-747-5748, 2Department of Agronomy & Horticulture, New Mexico State University, Las Cruces, NM, 88003, and 3Email: jgardea@utep.edu

ABSTRACT Previous batch laboratory experiments performed to determine the potential ability of seven different varieties of Medicago sativa (alfalfa) revealed that the African shoots population was able to efficiently bind copper(II) and nickel(II) from aqueous solutions. Batch laboratory interference studies were performed with various calcium and magnesium concentrations (0.1 mM to 1 M) in order to ascertain the effects of these ions on the heavy metal binding ability of African alfalfa shoots. Results from these studies have shown that calcium and magnesium did not seriously reduce the binding of copper(II) and lead(II) to African alfalfa shoots. However, high concentrations of calcium and magnesium significantly reduced chromium(III), cadmium(II), nickel(II), and zinc(II) binding to African shoots. In addition, all these experiments were repeated maintaining the ionic strength constant, and similar results were obtained. Interference studies were also conducted in order to determine the effects of hard cations under flow conditions with silica-immobilized African alfalfa shoots. The information obtained from these studies will be useful for an innovative method of heavy metal ion removal and recovery from contaminated waters.

KEYWORDS: bioremediation, phytofiltration, alfalfa, Medicago sativa, interference, heavy metal binding

This paper is from the Proceedings of the HSRC/WERC Joint Conference on the Environment, May 1996, published in hard copy and on the Web by the Great Plains/Rocky Mountain Hazardous Substance Research Center.

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