Treatment Of High Concentration Phenol Wastewater By DBD Synergistic Photocatalyst

Phenol is one of the most common organic pollutants in wastewater discharged from chemical industry.The discharge of phenol wastewater into water will cause great harm to the aquatic environment and human health.Due to its long toxicity and high degradation difficulty,the existing wastewater treatment methods,including adsorption,coagulation and biodegradation,cannot effectively remove phenol from water,and are prone to secondary pollution.Therefore,it is necessary to explore new methods for efficient removal of phenol in water environment.In recent years,dielectric barrier discharge（DBD）plasma technology has been widely used in wastewater treatment due to its advantages of easy operation,high efficiency and no secondary pollution.The active substances such as high-energy electrons,excited molecules and free radicals generated by discharge plasma can undergo a series of chemical reactions with organic pollutants in water,so as to achieve the purpose of degrading pollutants.However,the high energy electrons,active species and ultraviolet light produced by DBD plasma discharge cannot be fully utilized,which reduces the energy yield of the system.Therefore,in order to make full use of the energy generated by DBD plasma discharge to achieve the efficient degradation of organic pollutants in wastewater,this paper explored the synergistic degradation of target pollutant phenol by DBD plasma technology combined with TiO₂ photocatalyst.The main research results are as follows:（1）The effects of reaction conditions on the degradation of phenol in DBD system and synergistic system were explored.The phenol solution was treated by DBD water treatment reactor,and the single variable experimental studies were carried out on the reaction conditions such as initial phenol concentration,initial pH value of solution,input voltage and discharge distance.The results showed that when the input voltage was 80 V and the input current was 1.0 A,the degradation effect of phenol was the best when the discharge distance was 4 mm.The addition of catalyst not only improved the reaction efficiency but also shortened the reaction time.After the phenol solution was treated by the synergistic system for 120 min,the degradation effect of low concentration phenol was better,and the degradation rate of 100 mg/L phenol reached 99.4%.In addition,the synergistic system remained stable when pH changed.Under acidic conditions,the degradation effect of the synergistic system on phenol was better than that of the original solution.（2）Effect of metal ions on phenol degradation in the system.The experimental results show that both single system and synergistic system,in the presence of Cr⁶⁺,not only conducive to the degradation of phenol but also promote the reduction of Cr⁶⁺.In a single system,phenol removal efficiency increased to 99.5%,and the reaction rate was also accelerated.The removal rate of Cr⁶⁺also increased from 46.7%to 99.7%.It is also the same rule in the collaborative system.This may be because a large amount of H is consumed by Cr⁶⁺,hindering the reorganization of H and OH,increasing the concentration of OH,thereby enhancing the oxidation capacity of the system.（3）Speculation of phenol degradation pathway and synergistic mechanism.The degradation path of phenol in DBD water treatment reactor was speculated by analyzing the intermediate products of phenol.The mechanism of DBD degradation of phenol was explored by adding quencher CCl₄.After adding CCl₄,the removal efficiency of phenol increased from 93.5%to 97.1%.This indicated that DBD produced·H free radical in the treatment of phenol-containing wastewater.The addition of CCl₄ hindered the re-combination of·H and·OH,which eventually led to the improvement of phenol degradation efficiency.