Degradation Of 2,4-dichlorophenol By Dielectric Barrier Discharge

Chlorophenols pollution is widespread in the environment,which would cause serious harm to the health of organisms at low concentration.As an emerging technology of water treatment,non-thermal plasma could produce many kinds of physical and chemical effects,such as ultraviolet,local high temperature and so on,which effectively attack organic pollutants.In this paper,low-temperature plasma generated by dielectric barrier discharge(DBD)was used to remove 2,4-dichlorophenol(2,4-DCP)in wastewater,and related operations and water quality parameters were investigated.In order to make better use of the physical and chemical effects produced in DBD,the effect of adding various oxidants on the removal of 2,4-DCP and their difference was analysed.The experimental results showed:The removal and mineralization of 2,4-DCP could be improved by the increase of discharge power,frequency,carrier gas flowrate and the decrease of solution flowrate.Considering the stability and economy of discharge,the optimal parameters for the removal of 2,4-DCP were discharge power(250 W),diacharge frequency(17 kHz),carrier gas flowrate(15 L/min)and solution flowrate(50 ml/min).Under this condition,the removal and mineralization rate of 2,4-dichlorophenol was 69.77%and 31.85%.The initial pH and conductivity of the solution had a significant effect on the removal and mineralization of 2,4-DCP.In alkaline and netural condition and sodium chloride regulation,500μS/cm was more favorable for removal;four inorganic salts(NaCl、Na2SO4、Al2(SO4)3、AlCl3)were used to regulate the conductivity of solution to about 500 μS/cm respectively,and the order of degradation rate was NaCl>Na2SO4>Al2(SO4)3>control>AlCl3.The effect of solution characteristics on the removal of 2,4-DCP was the result of the interaction of conductivity,inorganic ions,dosage and pH.When four kinds of oxidants(hydrogen peroxide,sodium persulfate(SPS),sodium percarbonate(SPC),SPS+SPC)were added to the DBD reactor,the removal rate of 2,4-DCP was 100%,81.93%,76.37%and 90.02%respectively.The combination of SPS and SPC integrated the advantages of both oxidants,far higher than the effect of adding alone;the increase of initial conductivity(the addition of inorganic salt,SPC,SPS,etc.)reduced the concentration of NOx-,while the addition of hydrogen peroxide caused the production of NOx-much higher than the control sample.