Abstract:The paper reports the effects of pulse voltage amplitude on streamer discharge propagation at water surface. The subsequent chemical processes in a reactor following the surface discharges with different voltages are presented. A pulsed power modulator (PPM) system equipped with a control unit was employed to generate 0-25 kV pulses at 500 Hz. A point-plane electrode configuration was used for experiments, with the point electrode placed with 1 mm gap from the water surface in atmospheric air, and plane ground submerged with 30 mm gap in water. The streamer length at water surface was significantly influenced by the pulse voltage amplitude. Colorimetric measurement of hydrogen peroxide (H 2 O 2 ) and treatment of indigo carmine organic dye solution were carried out to elucidate the chemical processes produced at various pulse voltages. The experimental results reveal that the applied voltage is a factor that greatly affects water surface discharges and their chemical processes.
The properties of water surface discharge plasma for variety of pulse repetition rates are investigated. A magnetic pulse compression (MPC) pulsed power modulator able to deliver pulse repetition rates up to 1000 Hz, with 0.5 J per pulse energy output at 25 kV, was used as the pulsed power source. Positive pulse with a point-to-plane electrode configuration was used for the experiments. The concentration and production yield of hydrogen peroxide (H2O2) were quantitatively measured and orange II organic dye was treated, to evaluate the chemical properties of the discharge reactor. Experimental results show that the physical and chemical properties of water surface discharge are not influenced by pulse repetition rate, very different from those observed for under water discharge. The production yield of H2O2 and degradation rate per pulse of the dye did not significantly vary at different pulse repetition rates under a constant discharge mode on water surface. In addition, the solution temperature, pH, and conductivity for both water surface and underwater discharge reactors were measured to compare their plasma properties for different pulse repetition rates. The results confirm that surface discharge can be employed at high pulse repetition rates as a reliable and advantageous method for industrial and environmental decontamination applications.
The detailed study presented here has shown the effects of atmospheric streamer discharge plasma on undesired microorganisms in water like algae. Algae are water organisms classified separately from plants. They are known to cause many hazards to humans and the environment. Many factories and holiday places have problems with removing algae. This study presents data about pulse power discharge in the water with algae was presented. Algae were treated by high voltage pulsed discharge (using copper pin electrode). Plasma discharge effects like, shock wave, hydroxyl radical, electric field and ultraviolet light were investigated. Generally, plasma and plasma-chemical processes accompanying plasma discharges in water have received little study to date. This study shows the electric discharge phenomenon is useful to inactivation algae in the water and the killing effect of algae is showing. High voltage electrical discharge in water has been considered as a potential method of water treatment to kill microorganisms, negating the use of chemicals such as chlorine that leads to disinfection by-products which may additionally compromise human health. Many scientists are trying to know how to control and how to use pulse power discharge and concomitant effects. The aims of this work was to investigate the effectiveness of a high voltage pulse power discharge, with pulse energy of 5 Joules, in killing algae in the water. Water volume was 700 ml. The pin copper electrode diameter was 0.9 mm and different one it was screw electrode diameter 6 mm, diameter of the screw head was 10 mm and 80 mm length and the high voltage was applied on it. On the down site water tank was mesh electrode made from copper wires diameter of 0.1 mm was grounded. Water temperature was room temperature. Algae were added direct from different water tank. The results showed that the most useful mechanism for inactivation (killing) algae was shock wave, 100% algae were killing by it. In our case ultraviolet light, hydroxyl radicals, and strong electric field were not useful for killing algae. Water conductivity and pH did not change too much during experiments. Inactive algae did not change shape and size, but color became different. Non additive process, no chemicals, filtrations are required to be added to the water to inactivate and eliminate algae.
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