Experimental Study On Aqueous-phenol Degradation By High-voltage Pulsed Corona Discharge

The pulsed high-voltage corona discharge is a new technology of advanced oxidation technology in the field of organic waste-water treatment.The corona discharge can produce·OH, UV,ozone and other effects of oxidation to degradate the organic pollutants.Plasma technology has become a hot research field in recent years.This paper selected phenol as the target pollutant in water,introduced the hazards of phenol-containing water,pointed out the advantages of high-voltage pulsed corona discharge technology by comparing other waste-water treatment technologies.Some aspects of the high-voltage pulsed corona discharge to remove phenol were studied in this paper,such as power reactor,the matching between the power and the reactor,and the solution features.The degradation way of the phenol were discussed through analyzed the intermediate.Main conclusions are as follows:Corona discharged stably,the corona was wide,and could fill the space of reactor well when using three-dimensional electrode.The treated waste water was in the state of flowing. The match between power and reactor was good.Added Fe²⁺,Fe³⁺ and H₂O₂ could improve the efficiency of the degradation of phenol when use high-voltage pulsed corona discharge to treat waste-water.When added Fe²⁺,the raising extent of phenol degradation was the best,due to the formation of Fenton effect,followed by Fe³⁺,and H₂O₂ was the smallest.With the increase of the addition of the Fe²⁺,the efficiency of phenol degradation rose first,and then it went down.When used a three-dimensional electrode, electrode diameter wasΦ0.7 mm,pulsed peak voltage was 42 kV,pulsed frequency was 180 Hz, discharge spacing was 25 mm,oxygen as the bubbling gas,the rate was 6 L/min,Fe²⁺ concentration was 0.015×10^-3mol/L,the initial solution conductivity was 6μs/cm,pH value was 6,the efficiency of phenol degradation could reach 94.39%after 120 min treatment.The efficiency of the phenol degradation improved when increased the peak of pulsed voltage or pulsed frequency.Compared to the pulsed frequency,the pulsed voltage played a more important role to the degradation efficiency.Increase the number of electrodes,the rate of the bubbling gas,reduce the electrical conductivity and reduce electrode diameter appropriately, are all conducive to improving the efficiency of the phenol degradation.When use high-voltage pulsed corona plasma to degradate the phenol,first,the hydroxyl radical attacks the phenol molecules,form hydroquinone or adjacent phenol.Hydroquinone or adjacent phenol can be further oxidative and form diethyl phthalate.Diethyl phthalate then continue to be oxidated,benzene ring open and induce open-ring products,and then they can be further oxidated,generate Asia-acetic acid,acetone and other substances,eventually broken down into CO₂ and H₂O.