| AVS 61st International Symposium & Exhibition | |
| Plasma Science and Technology | Tuesday Sessions |
| Session PS-TuP |
| Session: | Plasma Science and Technology Poster Session |
| Presenter: | BrittanyPaige Bishop, Case Western Reserve University |
| Authors: | B. Bishop, Case Western Reserve University S. Ghosh, Case Western Reserve University I. Morrison, Case Western Reserve University D. Scherson, Case Western Reserve University R. Akolkar, Case Western Reserve University R.M. Sankaran, Case Western Reserve University |
| Correspondent: | Click to Email |
Reactions at the interface of a plasma and a liquid surface have recently become important for applications in wastewater treatment, materials synthesis, and therapy. These experiments are typically carried out between an atmospheric-pressure plasma jet and a static liquid surface (i.e. liquid bath or film). Here, we present a continuous plasma-liquid interface formed by an atmospheric-pressure microplasma and an open air, laminar flow liquid water jet.
A vertically falling water jet is formed in open air by pumping liquid water through a microcapillary. The stability of the water jet is explained by the Plateau-Rayleigh instability. At low flow rates, surface tension leads to the breakup of the jet into droplets. At high flow rates, the jet becomes turbulent and again breaks up. The water jet is found to be highly stable at intermediate flow rates where the water jet is laminar, with a relatively constant diameter of 500 μm over lengths of more than 30 mm. This allows the microplasma to be stably formed at the surface of the water jet and current to flow across the plasma-liquid interface to a counter electrode. The system is characterized with the microplasma operating by current-voltage measurements. We find that the overall resistance is strongly influenced by the inter-electrode distance and the ion concentration in solution, suggesting that solution conductivity dominates the electrical conductivity of our system. This is explained by a simple model based on a geometrical approximation for the water jet which shows that the resistance of the water jet is large because of the confined volume.
We have applied this newly developed system to the synthesis of metal nanoparticles. Aqueous solutions of silver nitrate are formed as a liquid water jet and pumped through the plasma-liquid interface. A distinct color change is observed as the silver nitrate is reduced by the microplasma to silver nanoparticles. The solutions are characterized by ultraviolet-visible (UV-vis) absorbance spectroscopy and transmission electron microscopy (TEM) which confirm crystalline, nanometer-sized silver particles. We find that the particle production rate depends on the plasma current and the liquid water jet flow rate, the latter of which is consistent with a space time approximation for the reactor.