| ozone is a widely used potent oxidizing agent,deodorant,and bactericide in medicine,agriculture and food industry,which mainly produced via oxygen discharge.Atmospheric Pressure Cold Plasma from Dielectric Barrier Discharge(DBD),having over a hundred year history,is one of the primary resource of ozone production in industry.Currently,plasma Ozone generators manufactured in our country still fall behind the world average.Its productivity and produced ozone concentration are dissatisfactory.Therefore,studies regarding plasma Ozone generators production and improvement remain its place under spotlight.The current study proposed a design of a plasma Ozone generators(hereafter refers to as the generator).Using DBD as chamber,external pulse power source could ionize pure oxygen and stably produce high concentration ozone products.Acquiring ozone product with different concentration by manipulating pulse paramaters such as pulse width,peek voltage and frequency,this study further discussed the affect of pulse paramaters on ozone product concentration in terms of electrical parameter of DBD plasma,waveforms of electrical current and voltage and the distribution of high-energy electrons.As the effect of high-energy electrons(promote ozone production),low-energy electrons(promote ozone decomposition)and Ozone thermal decomposition happens simultaneously,between 0 and 1?S pulse width,the ozone concentration was positively correlated with pulse width and reached the peek of 128g/Nm~3(pulse width 1?S).When pulse width exceeded 1?S,the direction of the correlation was found altered and the concentration dropped to32g/Nm~3(pulse width 75?S).Regarding the effect of frequency,within 20?S pulse width,ozone concentration was positively correlated with frequency and reached the maximum of 150 g/Nm~3with 30k Hz frequency.However,under this frequency,ozone concentration and pulse width was negatively correlated.By contrast,under 5k Hz and 10k Hz frequency,the maximum ozone concentration decreased but the effect of pulse width was attenuated,among which the product concentration at10k Hz decreases at a moderate rate with the increase of pulse width,while the decrease at 5k Hz is relatively slow.When the pulse width increases to a certain extent,the ozone concentration at high frequencies is less than that at low frequencies.Further study suggested that with the same input energy and the number discharge,higher frequency accompanied with decreased cumulative ozone concentration,whereby increasing frequency could damage the ozone yeild.Peek voltage was found positively correlated with ozone concentration.As the Reduced electric field and The energy of the free electron increase with peek voltage,the ozone concentration increase with a relatively higher magnitude.This magnitude decreased and stablised after reaching a saturation value at 4.0 to 5.0k V due to ozone decomposition promoted by thermal effect.After 5.0k V,ozone concentration was found negatively correlated with voltage.The saturation concentration was mildly influenced by pulse width with a fluctuation of125-150 g/Nm3.However,between 2 and 4k V,the magnitude of pulse width on ozone concentration was more pronounced.This article end with a discussion regarding the decolorization effect of ozone with different concentration on dyeing wastewater.It was concluded that higher ozone concentration was associated with higher decolorization speed on methylene blue.All decolorization rate of the ozone concentrations tested in this study successfully reached 97-98%fixed saturation value,such that 156.3 g/Nm3 and 103 g/Nm3 ozone could fully decolorize wasterwater in 15 and 20 minutes receptively.However,ozone concentration lower than 50 g/Nm3 would require more than 1 hour to achieve the same affect. |
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