Investigation On Gas-Phase Discharge Plasma Reactors For Decomposition Of Organic Compounds In Water

Generation of stable discharge plasma state in gas phase is more easily than that in liquid phase (or gas-liquid phase). This article introduces three kinds of corona discharge reactors such as ceramic tube barrier wire-cylinder pulse discharge reactor, muti-needles-plate pulse discharge reactor and mutineedles-plate negative DC corona discharge reactor for degradation of organic compounds in water. In order to provide some useful information for future industrialization of high-voltage discharge plasma process, we study the decomposition efficiencies of typical organic compounds and the corresponding influence factors, and the reasons are also discussed. According to our research the main results are summarized as follows:(1) All of three kinds of discharge reactors are effective for decomposition of organic compounds in water. The decomposition rate of organic compounds increases with discharge voltage (or energy), and the decomposition rate with oxygen as the bubbling gas is higher than that with air as the bubbling gas. The conductivity of solution has little effect on organic compounds decomposition.(2) When ceramic tube barrier wire-cylinder pulse discharge reactor is used to degrade 250mL phenol solution with an initial concentration of 50mg/L, pH value around 7 and solution conductivity of 100μS/cm, the phenol decomposition rate and energy utilizing rate reach 71% and 0.51mg/Wh respectively, after 60min pulse discharge radiation (pulse peak voltage 20kV and pulse frequency 50Hz), and the solution circulation flux of 100mL/min and oxygen bubbling rate of 2.0L/min. Main intermediates are hydroquinone, resorcinol, 1,4-benzoquinone and pyrocatechol.(3) When muti-needles-plate pluse discharge reactor is used to degrade the phenol solution with an initial concentration of 500mg/L, under the same conditions except of the oxygen bubbling rate (2.0L/min), the decomposition rate of phenol is 30% and the energy utilizing rate reaches 0.65mg/Wh.(4) When muti-needles-plate type reactor is used to decolor dye solution, higher decoloration rate could be obtained when negative DC power served as the power supply. After 60min corona discharge radiation, the decoloration rate of 500mL amaranth solution with a concentration of 40mg/L reaches 88.6% under the negative voltage of 11.8kV and oxygen flux of 1.0L/min, and the energy utilizing rate reaches 1.1mg/Wh.According to the performances of three kinds of gas phase discharge plasma reactors, the negative DC corona discharge reactor with muti-needles-plate electrode configuration is feasible for degradation of organic compounds and suits for industrial application.