Poster Presentation 21
Analysis of a Gas-Liquid Film Plasma Reactor for Degradation of
Methylene Blue
Qiao Zhang
Department of Chemical and Biomedical Engineering, Florida State University, 2525 Pottsdamer Street
Tallahassee, FL 32310 USA
Abstract
Advanced oxidation process (AOP) for dye removal by non-thermal pulsed discharge plasma in water is of
growing interest. It is based on the generation of highly oxidized species such as hydrogen peroxide, ozone, and
especially hydroxyl radical. Degradation of methylene blue in a hybrid gas-liquid pulsed electrical discharge
plasma reactor was analyzed with flowing carrier gas of argon mixed with oxygen. The effect of inlet oxygen
concentration, liquid conductivity, dye type and liquid flowrate on dye decoloration and degradation and
hydrogen peroxide production were determined. Effluent ozone concentration in the gas phase was determined
by standard indigo method.
In liquid phase analysis, the results show that adding oxygen does not significantly change dye decoloration and
TOC removal, yet it does affect the hydrogen peroxide production rate. The highest dye decoloration was
achieved in pure argon. Our hypothesis was that OH radical from the plasma goes into the liquid to decolor dye
and react with dye and dye breakdown products. While ozone is formed in the gas, mass transfer of ozone into
the liquid is limited by perhaps the short contact time for the ozone with the liquid and also by the lower
solubility of ozone in the liquid and perhaps the lower rate of ozone reactions with the dye, which hasn’t been
proved yet.
Higher initial liquid conductivity resulted in lower ozone concentration and hydrogen peroxide production rate.
In this case, more input power was dissipated by bulk liquid instead of plasma channel. Ozone and hydrogen
peroxide production was decreased as a reason of less discharge power.
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