Study On Decomposition Of Mixed Gaseous VOCs By Corona Discharge Combined With Water Absorption

With the fast development of technology, the scope of volatile organic compounds (VOCs) diffused into the atmosphere are becoming bigger and bigger, the prevention and control measure of VOCs has been widely concerned by public. The present methods to purify organic gaseous pollutions, such as combustion, absorption, and adsorption, have a certain defects on economic and technology aspects, escpecially to the large flow and low concentration organic gases. Nowaday, non-thermal plasma technology are developed to handle with the air pollution problems, it could un-selectively and instantaneously degredate multiple gaseous pollutions at ambient temperature and pressure, with simple process, short time and low energy consumption.Experimental research on degradating miex gaseous VOCs by pulse corona discharge combined with water absorption is discussed in this paper, Trichloroethylene and 1,3-xylene are chosen as representational matters, and the samples are analyzed by gas chromatography. First, the match of pulse power supply and reactor configuration on the removal efficiencies of mixed VOCs is investigated, including pulse power supplies, pulse forming capacitances, frequency, discharge spacing and so on. Then the reasons of these effects are analyzed from the view points of input power and energy density. On the basic of above experiments, the effects of combining water absorption with pulse corona discharge on the removal efficiency of mixed VOCs are studied. In addition, the mechanism of corona discharge combined with water absorption is discussed. The results are summarized as follow:1. The characteristics of pulse high voltage power supply matching with the electrode configuration of plasma reactor is very important to the input power and decomposition of gaseous organic pollutants. Compared to monopolar pulse high voltage, bipolar pulse high voltage could inject more discharge power into the reactor. Pulse forming capacitance affects the instantaneous micro-discharge process. As edge electrodes are used, whose streamer is more stabilized, the energy utilization ratio is higher. Improving the electrode spacing can effect the appropriate distribution of discharge power. In this experiment, when the pulse forming capacitor is 0.8nF, bipolar power supply and edge-plate reactor reach a better match, then in the peak voltage of 21.6kV, the removal rates of TCE and M-xylene reaches 50% and 75%. 2. Combining pulse corona discharge with water absorption, the removal rates of TCE and M-Xylene get higher, and somhow the degree is even higher with increasing the initial pH or decreasing the temperature. In the case of water volume at 300mL, temperature at 25℃and pH at 11.0, the removal efficiencies of TCE and M-Xylene with absorption process are 12% higher than that without absorption process, and reach 62%,89% respectively.3. The essence of water absorption is the advanced oxidation process of hydroxyl radical. When the water absorption device is added, Ozone generated by corona discharge is accumulated in water, and then transformed into hydroxyl radical with high oxidative ability; eventually the organic pollutants in the water are oxidative degradated.