Experimental Study On Decomposing Indoor Pollutants With Radical Shower Induced By DC Corona Discharge

The thesis first reviewed severe adverse effects on human health of indoor air pollution and the pollution actuality, while introduced various purifying indoor air technologies including the traditional and new ones. Then the advantages of Removal of Indoor Air Pollutants Using a Corona Radical Shower System was indicated.Density functional theory (DFT) of quantum chemistry was briefly introduced. HF and MP2 methods of the ab-initio theory and B3LYP method of density functional theory all with 6-31G (d) basis set, were employed to optimize the equilibrium geometry molecule configuration and energy. The values calculated with HF and MP2 were higher than the ones with B3LYP, while B3LYP provided more accurate results which well matched the experiment ones. Based on this, the bond dissociation energies (BDE) were calculated with B3LYP method in some basis levels. The results performed well with experiment values, showing high potential in BDE calculations.The results varying between 4eV and 5eV showed that the BDEs of free radical resources were far less than that of N₂ (main component in background gas).According to the corona discharge simulation of previous researchers and electron energy average distribution, the electron energy mainly distributed between 5eV and 20eV in the whole process. The combination of theoretical calculations and relevant experiments showed that the high energy electron can dissociate free radical resources to O or OH radicals availably.Using O₂+H₂O as radical resources , the experiments on formaldehyde degradation in atmospheric pressure were carried out. The results showed that O, OH and HO2 radicals played an important role on formaldehyde removal. Degradation effect with nozzle electrode located perpendicularly to the plate electrode was better than that with nozzle one parallelly to the plate electrode. Choosing the nozzle ofφ3 mm can obtain the better formaldehyde removal efficiency. And reducing theformaldehyde initial concentration was advantageous to increase degradation efficiency. It demonstrated that removal of indoor air pollutants using a corona radical shower system was suitable.The intensive investigation had been carried out on formaldehyde removal and degradation process by plasma, which covered various reaction mechanisms and difficulty degrees. It was showed during the plasma discharge reaction with radical...