A Discovery-Based Experiment Illustrating How Iron Metal Is Used to Remediate Contaminated Groundwater

Barbara A. Balko
Department of Chemistry, Lewis & Clark College, Portland, OR 97219-7899
Paul G. Tratnyek
Department of Environmental Science and Engineering, Oregon Graduate Institute of Science & Technology, Beaverton, OR 97006-8921
J. Chem. Educ., 2001, 78 (12), p 1661
DOI: 10.1021/ed078p1661
Publication Date (Web): December 1, 2001

Abstract

In this article, we describe an experiment for undergraduate general chemistry in which students investigate the chemistry behind iron-permeable reactive barriers (iron PRBs), a new technology that is widely used to remediate contaminated groundwater. Contaminant remediation involving iron PRBs is a redox process: the iron metal undergoes oxidative dissolution while the contaminant is reduced. The reaction is complicated, however, by the fact that it involves a surface that changes owing to the development of a layer of rust (iron oxide) on the iron. In this experiment, students examine the iron PRB-contaminant reaction by characterizing the kinetics of the degradation of a dye (the model contaminant) in the presence of granular iron under various experimental conditions. Students can be asked to design their own experiments to investigate aspects of the degradation reaction that are of particular interest to them. The material covered in the lab includes oxidation-reduction reactions, pseudo first-order kinetics, spectrophotometry, and the application of chemistry to solving environmental problems. The experiment can also be used as a vehicle to introduce more advanced topics in chemistry such as heterogeneous reactions, corrosion, passive film growth, and mass transport.

Keywords (Audience):

High School / Introductory Chemistry

Keywords (Domain):

Environmental Chemistry

Keywords (Pedagogy):

Inquiry-Based / Discovery Learning

Keywords (Subject):

Kinetics

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History

  • Received: August 03, 2009

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