CHARACTERIZATION OF CHROMIUM(VI) BINDING AND BIO-REDUCTION BY AVENA
MONIDA (OAT) BIOMASS
1
L. Bess-Oberto, 1V. Armendariz, 1K.J. Tiemann, and 2J.L. Gardea-Torresdey
1,2
Department of Chemistry and Environmental Science and Engineering, University of Texas at El
Paso, El Paso, TX 79968; 2Phone: (915) 747-5359, 2E-mail: jgardea@utep.edu.
The contamination of chromium(VI) in the environment and the consequences of this
potential health threat have become an important issue. Conventional technologies to clean up
heavy metal from contaminated waters have been utilized, but they are not cost-effective.
Agricultural waste by-products may be a new cost-effect alternative for the removal of
chromium(VI) from contaminated waters. Oat by-products from the Juarez Valley in Mexico were
studied for the ability to bind chromium(VI) under temperature and time effects. Batch
experiments were performed at various time exposures and temperatures to determine their effects
on the chromium(VI) binding capacity by oat biomass at pH 2.0. The metal-binding ability of oats
was calculated from experimental data collected at time exposures of 1, 6, 24, 48, and 72 hours at
each temperature of 8°C, 26°C, and 54°C. These results showed that the binding of Cr(VI) to oat
biomass increased with increasing time and temperature. The chromium recovery from oat biomass
was performed by treatment with 0.2 M HC1. The strippings were further analyzed with UV-VIS
spectroscopy where it was determined that chromium(VI) was reduced to chromium(III) by the oat
biomass. These results were confirmed using x-ray absorption spectroscopy which proved the
reduction of Cr(VI) to Cr(III). This agricultural waste byproduct could be a good alternative for the
removal of chromium(VI) from contaminated waters and for the minimization of the contaminated
levels in water due to the reduction of Cr(VI) to Cr(III).
Key words: chromium(VI);, bioreduction, oats, agricultural by-products, XANES