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The Use of Alfalfa (Medicago sativa) to Recover Chromium(III) and Chromium(VI) from Aqueous SolutionEPA Grant Number: U915583
Title: The Use of Alfalfa (Medicago sativa) to Recover Chromium(III) and Chromium(VI) from Aqueous Solution
Investigators: Dokken, Kenneth M.
Institution: The University of Texas at El Paso
EPA Project Officer: Broadway, Virginia
Project Period: July 1, 1999 through August 1, 2001
Project Amount: $50,583
RFA: STAR Graduate Fellowships (1999) RFA Text | Recipients Lists
Research Category: Academic Fellowships , Fellowship - Bioremediation , Hazardous Waste/Remediation
The objective of this research project is to develop a cost-effective, environmentally friendly phytofiltration system using alfalfa (Medicago sativa) to recover trivalent and hexavalent chromium from contaminated waters.
Batch experiments have been conducted to determine optimal binding pH, temperature, and time. Capacity studies have been performed to determine the amount of chromium the biomass can adsorb (mg chromium/g biomass). Modification studies that involve esterifying and hydrolyzing the biomass were conducted to help ascertain which ligands might play an important role in chromium binding. In addition, flow studies were conducted using silica-immobilized biomass. A chromium solution is pumped through a column containing the silica-immobilized biomass, and the effluents are collected and analyzed for chromium concentration. X-ray microfluorescence studies were performed to further prove that the chromium binds to the alfalfa biomass, as indicated by the batch studies. X-ray absorption spectroscopy (XAS) studies were conducted at the Stanford Synchrotron Laboratories to help characterize the binding mechanism(s) involved in the binding of Cr(III) and Cr(VI) by the alfalfa biomass. Two XAS techniques were utilized: X-ray Absorption Near Edge Structure (XANES) and Extended X-ray Absorption Fine Structure (EXAFS). These techniques determine the oxidation state of the chromium being bound to the biomass and the ligands to which chromium may be binding on the surface of the biomass.