Research On Phenol Wastewater Treatment By High Voltage Pulse Discharge In Gas-Liquid Two Phases Combined With Catalysts

Organic wastewater treatment by high voltage pulse discharge in gas-liquid two phases is a new and efficient technology in wastewater treatment.Widely research is applied to degradation of all kinds of organic wastewater because it can generate low selectivity of free radicals and active substances.In order to make full use of the UV-light released by discharge and achieve the high effective degradation of the nocuous organics in wastewater,a degradation system of discharge in gas-liquid two phases-photocatalysis was composed of photocatalysts and high voltage pulse discharge in the experiment.In this paper,phenol synthetic water was the object of study.The experiment systematic studied the water treatment technology of high voltage pulse discharge in gas-liquid two phases combined with catalysts from several aspects,such as the impact of the reactor structure,the impact of the discharge parameters,the impact of catalysts,the analysis of byproducts,and the mechanism of degradation.The main conclusions in this paper ware as follows:?1?The electrical parameters and reactor parameters had great influence on phenol degradation rate in the process of phenol synthetic water treated by high voltage pulse discharge in gas-liquid two phases.Phenol degradation rate increased with the increase of pulse voltage and which tended to stable while the pulse voltage reached a certain value.As the increase of the electrode spacing,needle-liquid spacing,pulse frequency,air volume,the degradation rate of phenol increased,but,the degradation rate of phenol would decrease while each factor reached the certain value.?2?The phenol degradation rate was 64.63% when 100 mL concentration of 100 mg/L of phenol wastewater was treated by high voltage pulse discharge in gas-liquid two phases for 60 min,under the best condition of 10 mm electrode spacing,7.5 mm needle-liquid spacing,26 kV pulse voltage,70 Hz pulse frequency and 1.5 L/min aeration.In addition,the phenol degradation rate reached 85.02% when wastewater was treated for 140 min.The general trend of four kinds of byproducts' concentration increased firstly and then decreased gradually and eventually reached zero with the increase of discharge time.Besides,the concentration of benzoquinone was the largest,the resorcinol was the lowest and appeared in two stages,and catechol disappeared at first.?3?The experiment of phenol wastewater treated by high voltage pulse discharge in gas-liquid two phases respectively combined with TiO₂ and Fe-TiO₂ showed that the phenol degradation increased with the calcination temperatures and dosages of catalyst,and then decreased.The experimental results and the electron microscope scanning test results together showed that the optimum calcination temperatures of TiO 2 and Fe-TiO₂ ware 500? and 450? respectively,and the optimum dosages of the two catalysts ware 1.0g/L and 0.5g/L respectively.?4?Compared to high voltage pulse discharge in gas-liquid two phases treated phenol wastewater,the peak concentrations of byproducts increased when phenol wastewater was treated by high voltage pulse discharge combined with TiO₂.But the fall rate of byproducts concentrations was accelerated after the peak concentrations.And the TOC of solution was lower,the mineralization rate increased.The phenol degradation reached a better level when pulse discharge was combined with Fe-TiO₂,degradation rate was 98.75% with 140 min and the concentration of byproducts obviously reduced.Resorcinol completely disappeared in the process.The fall rate of TOC accelerated and the mineralization rate obtain a further promotion.?5?The research also analyzed the forming mechanism of active substances in high voltage pulse discharge in gas-liquid two phases and the mechanism of phenol treated by high voltage pulse discharge combined with catalysts.The analysis showed that a few of phenol was degraded into CO2 and H2 O in the treatment process,part of phenol was degraded into byproducts first,and mineralized as the extension of discharge time.There would provide certain reference for organic compounds degraded by discharge plasma combined with catalysts in wastewater.