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Surface Specific Studies of Physical and Chemical Processes Involving Metal Contaminants in Soils Using Nonlinear Laser Spectroscopy Techniques

EPA Grant Number: F5B20242
Title: Surface Specific Studies of Physical and Chemical Processes Involving Metal Contaminants in Soils Using Nonlinear Laser Spectroscopy Techniques
Investigators: Mifflin, Amanda L.
Institution: Northwestern University
EPA Project Officer: Thompson, Delores
Project Period: September 1, 2005 through August 1, 2006
Project Amount: $103,572
RFA: STAR Graduate Fellowships (2005)
Research Category: Academic Fellowships

Description:

Objective:

This project investigates the physical and chemical processes that control hexavalent chromium interactions with mineral/water interfaces using nonlinear optical laser spectroscopy.

To gain a detailed kinetic and thermodynamic understanding of pollutant binding to geosorbent surfaces for developing improved models that predict the fate and transport of heavy metal ions and toxic chemicals released into the environment, leading to more cost-effective remediation strategies.

Approach:

The sorption behavior of Cr(VI) is tracked in situ and in real time using the surface-specific spectroscopy technique second harmonic generation (SHG). The ligand-to-metal charge transfer bands of the chromate ions allow us to track Cr(VI) binding to various aqueous/solid interfaces, chosen as a simple heterogeneous mineral oxide/water system for these laboratory studies. Thermodynamic, kinetic and spectroscopic data are obtained in real time at environmentally relevant chromate concentrations and pH ranges.

Expected Results:

Experiments will examine Cr(VI) binding to various organic functional groups found in soils that have been chemically tethered to the silica surface. Binding parameters for each surface will be determined quantitatively and with surface-specificity. Kinetic parameters, such as adsorption and desorption rate constants, will be obtained through adsorption-desorption studies in the submonolayer regime. We have determined that these parameters are able to differentiate between the chemistries of the different surfaces, and are investigating how they can be best incorporated into transport models.

Supplemental Keywords:

Second harmonic generation, nonlinear optics, chromium, pollutant binding, transport models, mineral surfaces, , Water, Scientific Discipline, Waste, Environmental Engineering, Environmental Chemistry, Contaminated Sediments, remediation, fate, chemical transport, nonlinear laser spectroscopic techniques, contaminated sediment, metal contamination, chemical contaminants

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The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.

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