Some chemical properties of plasmas created in liquid solutions

Underwater electrical discharges have become a major focus of study recently primarily due to their many practical applications. Such applications include degradation of hazardous organic compounds, killing of microorganisms, chemical synthesis and electrosurgery. A small multi-electrode system is used. The plasma is created using a small ($\sim $ 3.5 mm diameter) four electrode circular device with a coaxial earth and with each electrode driven with 100 kHz RF bipolar square wave voltage. Four different inorganic solutions were used: 0.15 mol KCl, NaCl, BaCl$_{2}$ and Na$_{2}$CO$_{3}$. These solutions were at room temperature at the start of experiment and were gradually brought to boiling. The chemical and physical plasma properties were studied. Optical emission spectroscopy has been used to demonstrate OH radical production which is important since this species is known to react readily with many pollutants. In all solutions except Na$_{2}$CO$_{3}$ hydrogen peroxide generation was also observed also. Hydrogen peroxide is one of the most important species which the plasma produces because it helps with water treatment. The pH values were examined also but remained stable during all measurements.