Kinetic and Mechanistic Framework for Remediation Using Zerovalent Iron (SEERII)EPA Grant Number: R829422E03
Title: Kinetic and Mechanistic Framework for Remediation Using Zerovalent Iron (SEERII)
Investigators: Zhang, Tian C. , Shea, Patrick J.
Institution: University of Nebraska at Lincoln
EPA Project Officer: Hunt, Sherri
Project Period: August 5, 2002 through August 4, 2004 (Extended to August 4, 2005)
Project Amount: $215,061
RFA: EPSCoR (Experimental Program to Stimulate Competitive Research) (2001) RFA Text | Recipients Lists
Research Category: EPSCoR (The Experimental Program to Stimulate Competitive Research)
This project further investigates zerovalent iron (Fe0) as an alternative remediation technology for treating soil and water contaminated with nitrate and chlorinated or nitrogenated organic compounds. Project objectives of our project are to: (1) elucidate the kinetics and mechanisms of Fe0 treatment processes, (2) develop new approaches to enhance Fe0 performance, and (3) implement a successful cleanup of a contaminated field site. Major hypotheses are that (1) the semiconducting properties of (hydr)oxides coating the Fe0 surface and electric field enhancement arising from surficial cations are major operating mechanisms for effective contaminant reduction during oxidation of Fe0, and (2) the performance of Fe0 treatment systems can be enhanced by certain amendments (such as aluminum and iron salts) and optimizing reaction conditions (particularly Eh and pH). Therefore, with careful management, Fe0 treatment processes can be sufficiently robust for effective yet practical on-site remediation.
The project will be conducted using batch and column reactors and field-scale equipment. To approach Objective 1, the reduction of nitrate, chlorinated and nitrogenated organic contaminants by Fe0 will be studied. Major hypotheses centering on process kinetics and mechanisms (semiconductor and electric field enhancement) and the role of iron oxides (particularly magnetite and green rusts) in promoting chemical reduction will be tested. A "Langmuir" model describing the process will be developed and tested. To approach Objective 2, technologies to regenerate reactive sites, remove passivating films, overcome clogging of permeable Fe0 barriers through addition of aluminum and iron salts, and optimize reaction conditions (primarily pH and Eh) will be developed. Finally, a field demonstration project will be conducted (Objective 3) to test the technologies developed in the laboratory.
The proposed kinetic model will be calibrated using experimental results. Several new procedures for enhancing Fe0 treatment processes will result from the project. Further evaluation of the roles of iron oxides and environmental variables will lead to broader use of this promising treatment technology. A successful field demonstration is anticipated.