Hydroxyl radical production via the photo-Fenton reaction in natural waters

This dissertation investigates the importance of photo-Fenton chemistry in natural waters. The Fenton reaction, H202 + Fe(ll) [right arrow] Fe(ll) + OH- + OH', can occur in sunlit waters because both H202 and Fe(ll) are photo-chemically produced. Photo-Fenton chemistry was investigated by irradiating model systems and natural water samples with simulated sunlight and measuring both H202 accumulation and OH' production in the presence and the absence of Fe reactions. Using these data, a model was developed to calculate the potential impact of the photo-Fenton reaction in sunlit natural waters. Throughout this work, a method based on the chemiluminescent reaction of an acridinium ester compound with the conjugate base of H202 was used to analyze H202. This method is sensitive, and has a greater dynamic range, greater selectivity, and fewer sources of interference than more commonly used methods. However, its behavior is not consistent with a simple reaction mechanism. The kinetics of the chemiluminescent reaction were investigated and a mechanism proposed that can explain its behavior, confirming the ability of this method to accurately measure H202, and suggesting ways to avoid potential problems with its application. The photo-Fenton reaction was studied in model systems consisting of a standard humic substance and amorphous iron oxide exposed to simulated sunlight. A probe method was adapted to allow low concentrations of OH' to be measured without otherwise influencing the chemical reactions occurring in experiments. The difference between measured H202 accumulation in the presence and absence of Fe in these systems was interpreted as the photo-loss of H202 by reaction with Fe(ll).

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Civil and Environmental Engineering.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2002

Author dc:creator

• Southworth, Barbara A. (Barbara Anne), 1973-

Advisor dc:contributor.advisor

• Bettina M. Voelker.

• Civil and Environmental Engineering.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/17548

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/17548