Shawnee A



J.L. Gardea-Torresdey, J. Bibb, and A. Hernandez, Department of Chemistry, The University of Texas at El Paso, El Paso, TX 79968 Larrea tridentata (creosote bush) is a plant that grows in the desert environment abundantly. This desert plant has been found naturally growing in heavy-metal contaminated soils. Previous experiments showed that the inactivated biomass of creosote bush was able to adsorb Cu(II) ions from aqueous solutions. The copper binding capacity of the creosote biomass that grows in heavy-metal uncontaminated soils was higher than the biomass that grows in heavy-metal contaminated soils.

Experiments were performed to determine the ability of creosote biomass (grown in heavy metal-uncontaminated soils) to adsorb Pb(II), Cd(II), and Ni(II) ions from aqueous solutions. Batch pH profile experiments for the indicated metal ions showed that the metal ion binding was different for every metal tested but increased as the pH was raised as high as 6.0. The metal binding as a function of pH also varied for the creosote's roots, stems, and leaves.

Experiments designed to determine how fast the metal ion adsorption process occurs, showed that the metal uptake is quite rapid. This suggests a metal surface binding mechanism. Binding capacity experiments showed the following amounts of metal ions bound per gram of creosote biomass: roots, 53.5 Pb(II), 20.1 Cd(II), 11.0 Ni(II); stems, 52.2 Pb(II),18.0 Cd(II), 9.1 Ni(II); and leaves, 58.2 Pb(II), 20.8 Cd(II), 11.4 Ni(II). A more significant binding capacity for lead ions was observed.

A great portion of the adsorbed lead, cadmium, and nickel by the creosote's roots, stems, and leaves was desorbed by treatment with 0.1 M HCl (up to 99% in some cases). Results of Cr(III), Zn(II), and Cr(VI) binding to creosote biomass will also be presented. Biomass of creosote bush may prove to be useful to remove and recover metal ions from contaminated waters by using a creosote phyto-filtration system.

Key words: Larrea tridentata, metal binding, phyto-filtration

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Tuesday, May 20, 1997

Metals Kansa A

Remediation of Munitions Compounds Kansa B

Analytical Methods Kansa C/D

General Topics Kansa B

Wednesday, May 21, 1997

Metals Kansa A

Zero-Valent Metals Kansa A

Remediation Kansa A

Vegetation-based Remediation Kansa B

Partnerships & Innovative Technologies Kansa C/D

Nonaqueous Phase Liquids Kansa C/D

Thursday, May 22, 1997

Biofilms & Barriers Kansa A

Bioremediation Kansa B

Partnerships & Technology Innovations Kansa C/D

Remediation Kansa C/D