Controlled plasma–droplet interactions: a quantitative study of OH transfer in plasma–liquid interaction
- Univ. of Minnesota, Minneapolis, MN (United States); Mitsubishi Electric Corporation, Hyogo (Japan); University of Minnesota
- Univ. of Minnesota, Minneapolis, MN (United States)
- Univ. of Minnesota, Minneapolis, MN (United States); Ruhr Univ., Bochum (Germany)
Plasmas in contact with liquids are a rich source of OH radicals and have been extensively studied in the last decade to leverage the ability to generate chemically reactive species in gas phase plasmas to decompose organics. Multiphase transfer of OH radicals is highly transport limited and to overcome transport limits, the plasma activation of aerosols, small liquid droplets, interspersed in the plasma has been proposed. In this work, we report a combined experimental and modeling study of a controlled plasma–droplet interaction experiment using a diffuse RF glow discharge in He + 0.2% H2O with detailed plasma diagnostics, ex situ analysis of the plasma-induced chemistry in the droplet containing formate, droplet trajectory and size measurements. This enables a quantitative study of the reactivity transfer of OH from the gas phase plasma to the liquid phase and how its diffusion limitations impact formate decomposition in the water droplet. For a droplet with a diameter of 36 μm, we observed 50% reduction in formate concentration in the droplets after plasma treatment for droplet residence times in the plasma of ~10 ms. These short droplet residence times in the plasma allow in some cases for droplet size reductions of ~5% in spite gas temperatures of 360 K. A one-dimensional reaction–diffusion model was used to calculate the OH transport and formate oxidation inside the droplet and was able to predict the conversion of formate by plasma in a droplet without any fitting parameters. The model further shows that formate conversion is dominated by near-interfacial reactions with OH radicals and is limited by diffusion of formate in the droplet. Here, the results show that a controlled plasma–micro-droplet reactor as reported in this study might be an excellent tool for detailed quantitative plasma–liquid interaction studies.
- Research Organization:
- Univ. of Minnesota, Minneapolis, MN (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Fusion Energy Sciences (FES)
- Grant/Contract Number:
- SC0001939
- OSTI ID:
- 1787664
- Alternate ID(s):
- OSTI ID: 23023143
- Journal Information:
- Plasma Sources Science and Technology, Journal Name: Plasma Sources Science and Technology Journal Issue: 9 Vol. 29; ISSN 1361-6595
- Publisher:
- IOP PublishingCopyright Statement
- Country of Publication:
- United States
- Language:
- English
Similar Records
Plasma-droplet interaction study to assess transport limitations and the role of •OH, O•,H•,O2(a1Δg),O3, He(23S) and Ar(1s5) in formate decomposition
Effect of water droplet growth dynamics on electrode current in fuel-cell catalyst layers