About the Speaker

Dr. Stapelmann is an assistant professor who studies the generation and transport of reactive species and interactions of technical plasmas with biological systems on a macromolecular level. Her focus is on the characterization and optimization of plasma discharges used for biomedical applications and the understanding and improvement of plasmas used e.g. in medicine and agriculture. The applications range from wound healing to air purification, sterilization of medical instruments as well as for planetary protection purposes. Furthermore, plasma-liquid interactions and plasma discharges in liquids belong to the repertoire.

ne.ncsu.edu/pls

Abstract

Optimization of Generation and Transport of RONS for Efficient N Fixation in Plasma-Treated Water

Non-thermal plasma for nitrogen (N) fixation is a promising alternative to the energy-intensive Haber-Bosch (HB) process. N fertilizer is vital for plant productivity, with NH3 and NO3- being viable sources of N. However, the current practices come at the cost of environmental impact. Plasma has the potential for a more sustainable alternative: it can be operated with air and renewable energies, and N fixation can be achieved on demand and on-site. The most energy-efficient devices reported in literature are volume dielectric barrier discharges (DBDs). A direct comparison with HB indicates need for improvement. Here, we are using a holistic approach to optimize N fixation. A DBD is used to generate reactive oxygen and nitrogen species (RONS). The composition is optimized based on electrical and optical data in conjunction with a 0D chemistry model. The transport of RONS into the liquid is maximized by the volume to surface ratio with the use of a sparger disc to create small bubbles. Gas flow is balanced between gas residence time in the plasma, bubble size, and bubble residence time in the water. By considering the whole system, it was found that NO3-is saturated in the liquid, slowing down the transport, before a plant-viable concentration is achieved. As many other NxOy, decompose in the liquid to NO3-, higher concentrations and more efficient transport can be achieved by focusing on the production of those species rather than optimizing the plasma to produce NO3-directly.