HCOO^-_aq Degradation in Droplets by OH_aq in an Atmospheric Pressure Glow Discharge

Journal Article · 31 March 2023 · Journal of Physics. D, Applied Physics

DOI: https://doi.org/10.1088/1361-6463/acc958 · OSTI ID:1969850

Meyer, Mackenzie ^[1]; Nayak, Gaurav  ^[2]; Bruggeman, Peter  ^[2]; Kushner, Mark J.  ^[1]

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1. Univ. of Michigan, Ann Arbor, MI (United States)
2. Univ. of Minnesota, Minneapolis, MN (United States)

Plasmas in contact with liquids can degrade organic molecules in solution, as reactive oxygen and nitrogen species produced in the plasma solvate into the liquid. Immersing small droplets (tens of microns in diameter) in the plasma can more rapidly activate the liquid compared to treating a large volume of liquid with a smaller surface-to-volume ratio. The interactions between a radio frequency glow discharge sustained in He/H₂O and a water droplet containing formate (HCOO^-_aq) immersed in and flowing through the plasma were modeled using a 0-dimensional global plasma chemistry model to investigate these activation processes. HCOO^-_aq interacts with OH_aq, produced from solvation of OH from the gas phase. HCOO^-_aq concentrations were benchmarked with previously reported experimental measurements. The diameter of the droplet, initial HCOO^-_aq concentration, and gas flow rate affect only the HCOO^-_aq concentration and OH_aq density, leaving the OH density in the gas phase unaffected. Power deposition and gas mixture (e.g., percentage of H₂O) change both the gas and liquid phase chemistry. A general trend was observed – during the first portion of droplet exposure to the plasma, OH_aq primarily consumes HCOO^-_aq. However, O2^-_aq, a byproduct of HCOO^-_aq consumption, consumes OH_aq once O2^-_aq reaches a critically large density. Using HCOO^-_aq as a surrogate for OH_aq sensitive contaminants, combinations of residence time, droplet diameter, water vapor density, and power will determine the optimum remediation strategy.

• Research Organization: Univ. of Minnesota, Minneapolis, MN (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Fusion Energy Sciences (FES); US Army Research Office (ARO)
• Grant/Contract Number: SC0020232; W911NF-20-1-0105
• OSTI ID: 1969850
• Journal Information: Journal of Physics. D, Applied Physics, Vol. 56, Issue 28; ISSN 0022-3727
• Publisher: IOP PublishingCopyright Statement
• Country of Publication: United States
• Language: English