| The pulsed high voltage discharge is a newly developed advanced oxidation technology of removing hazardous organic compounds from water solutions. The technology gathers high energy radiation, chemical oxidation and photocatalysis in one process, and has no use for oxidants, heating, high pressure and UV light source. Therefore, the technology is potential for a propagation industry application.Some basic factors of the technology were investigated in the paper, such as the output characteristic of the power source, the discharge characteristic, parameter optimum, active species formation, organic degradation and the degradation mechanism. The main results present in the paper are as follows:a) The output of pulsed high voltage power was sharply influenced by different combination of the spark gap-current limiting element and the conductivity in the reactor. The waveform of the voltage had two peaks in one pulse in the circuit of single spark gap/inductance, and the input energy was much higher than that in the double spark gap/resistor when the AC IN was lower. The discharge was influenced by reactor parameter such as electrodes distance, conductivity and input energy. The power circuit and the discharge reactor presented the some coupling character. The output of the pulsed high voltage power was affected by the processing parameter of the the reactor, and the discharge characteristic was influenced by the power output.b) The pulsed high voltage power efficiency and energy utilization efficiency by 4-CP degradation was highest in the system using double combination of spark gap-resistor. The optimum circuit parameter for the power unsed in the paper was: positive high voltage, 3nF of pulsed capacitor, double spark gap and resistor as current limiting elements. The the effect of conductivity on 4-CP degradation was more obvious in the reactor without bubbling than that in the reactor with bubbling gas. The optimum technology parameter for system was: peak voltage, 22.1kV; frequency, 150Hz; non-bubbling reactor recommended for the conductivity more than 34.7 (is/cm and bubbling reactor recommended for the conductivity more than 34.7 us/cm, aeration flux, 60L/h; electrode distance, 2cm for underwater or lcm for ground electrode and liquid level.c) The 4-CP degradation was in accordance with the magnitude of the hydroxyl radical formation by analyzing the active species formation. Arranged by magnitude, the hydroxyl formation rates at different bubbling were as follows: nitrogen, air, oxygen, no-bubbling. Bubbling gas changed the constituent of the discharge region and made the affection of the conductivity decreased. The hydroxyl radical was the main active species that promote the organic degradation by studying the mechanism of 4-CP degradation.d) The para of the hydroxyl was attacked by hydroxyl radical to form p-benzoquinone. Thep-benzoquinone was oxidized to open the ring and formed other intermittent products such as butanol, butanone, propanoic acid and ethanediol. The orthochlorophenol was attacked by hydroxyl radical to form 2,5-cyclohexadiene-l,4-hydroxyl-2-chloro, which was further oxidized to 2,5-cyclohexadiene-l,4-dione,2-chloro. The other intermediate products of o-chlorphenol degradation were metacetonic acid, oxalate, acetic acid and formate.The methyl red degradation in the system was due to radical reaction and one of the structure destruction routes was induced by the break of the azo bond. The main intermediate products were N,N-dimethy-l-4-nitrobenzene, paranitrophenol, glycerine and glycine,N-carboxymethyl. e) The mechanism of the 4-CP degradation was investigated in detail and a model was developed to describe the degradation process. The figure caculated by the the model was matched the experimental figure well for variation of 4-CP, Cl" and H2O2 concentration. Therefore, The model is useful for the magnification of the reactor and the propagation application of the technology.
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