Electrochemical Behaviors Of Oxidation And Reduction By Radical Under DC Discharge Plasma Atmosphere

At the both pressure of energy crisis and greenhouse effect owing to fossil fuel burning, more and more scientists are focus on carbon dioxide reduction and transformation. Carbon dioxide can be reduced into carbonaceous organic material, which can be used as fuel. As one of good energy, methanol is gaining more attention. DC corona discharge is one of good method to fulfill that reduction and transformation. Electrochemical behavior of carbon dioxide reduction with hydrogen in DC corona discharge at reductive atmosphere is studied in this thesis. Simultaneously, make pyridine degradation as example, electrochemical behavior of hydroxyl radical oxidization in DC corona discharge at reductive atmosphere is also studied.Reductive radicals generated by plasma system have stronger reduction ability than normal ones. High reductive radicals are generated by DC corona discharge at the presence of hydrogen as hydroperoxyl radical source, which can reduce CO2 to new organic molecules. Production detected by GC result shows that after 70h, methanol has been generated.Similarly, at the atmosphere of oxidation, oxidative radicals generated by plasma system have stronger oxidation ability than ozone. The essence of corona discharge plasma reaction is that high active radicals at the presence of water, mainly hydroxyl radicals. In this paper, representative heterocyclic volatile organic compound pyridine was degraded by DC corona discharge plasma at the presence of water as hydroxyl radical source.90.4% of pyridine could be removed at 20.75 kV and the initial concentration of pyridine was 8287 mg·m-3. Intermediates in droplet were detected by HPLC, indicating that fumaric acid and oxalic acid were the main intermediates, and nitrate was detected by ion chromatographic. Based on the above results, the possible degradation pathway of pyridine was proposed.Radicals generated in corona discharge actually happened in micro droplet from microscopic view. We found that when countless water vapor or cloud droplet disperse in humility air, every droplet can be considered as a micro electrolyzer, and its voltage range form 0.6 to 1.2 V and from0.8 to 2.0 V respectively. When anode and cathode of reactor are power on, positive charge and negative charge of droplet, pushed by high field, gathered to each side respectively and formed a small electric field. Each side with gathered charges, considered as anode and cathode, formed a micro electrolyzer, where most of chemical reactions happened.