Advanced oxidation degradation kinetics as a function of ultraviolet LED duty cycle

Authors

• Kelsey Duckworth, Air Force Institute of Technology
• Michael Spencer, Air Force Institute of Technology
• Christopher Bates, Air Force Institute of Technology
• Michael E. Miller, Air Force Institute of Technology
• Catherine Almquist, Miami University - Oxford
• Michael R. Grimaila, Air Force Institute of TechnologyFollow
• Matthew Magnuson, National Homeland Security Research Center
• Stuart Willison, National Homeland Security Research Center
• Rebecca Phillips, Oak Ridge Institute of Science and Education
• LeeAnn Racz, Air Force Institute of Technology

Document Type

Article

Publication Date

3-9-2015

Abstract

Ultraviolet (UV) light emitting diodes (LEDs) may be a viable option as a UV light source for advanced oxidation processes (AOPs) utilizing photocatalysts or oxidizing agents such as hydrogen peroxide. The effect of UV-LED duty cycle, expressed as the percentage of time the LED is powered, was investigated in an AOP with hydrogen peroxide, using methylene blue (MB) to assess contaminant degradation. The UV-LED AOP degraded the MB at all duty cycles. However, adsorption of MB onto the LED emitting surface caused a linear decline in reactor performance over time. With regard to the effect of duty cycle, the observed rate constant of MB degradation, after being adjusted to account for the duty cycle, was greater for 5 and 10% duty cycles than higher duty cycles, providing a value approximately 160% higher at 5% duty cycle than continuous operation. This increase in adjusted rate constant at low duty cycles, as well as contaminant fouling of the LED surface, may impact design and operational considerations for pulsed UV-LED AOP systems.

Comments

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DOI

10.2166/wst.2015.108

Source Publication

Water Science and Technology (ISSN 0273-1223)

Recommended Citation

Duckworth, K., Spencer, M., Bates, C., Miller, M. E., Almquist, C., Grimaila, M., Magnuson, M., Willison, S., Phillips, R., & Racz, L. (2015). Advanced oxidation degradation kinetics as a function of ultraviolet LED duty cycle. Water Science and Technology, 71(9), 1375–1381. https://doi.org/10.2166/wst.2015.108