The Study On The Degradation Of Complex Heavy Mental In Water By Dielectric Barrier Discharge

The complex heavy metal in electroplating wastewater is not only toxic but also non-biodegradable and easily build up in the body through the food chain.Compared with free state heavy metal ion which is common found in water,Alkali precipitation method does not make sufficient removing effect on complex heavy metal to meet national sewage discharge standard.So a new effective solution needs to be developed to remove the complex heavy metal without secondary pollution.In recent years,dielectric barrier discharge technique is widely concerned and researched due to its stability of discharge process and the remarkable degradation effect on organics by the active matters produced during the process.In this article dielectric barrier discharge technique is used in simulative Cu-EDTA wasted water and the removal mechanism and characteristic is studied.The conclusion is:（1）High pressure dielectric barrier discharge is effective to remove Cu-EDTA from the water,after 60 mins treatment the removal rate can hit 92%.Increasing discharge or ventilation flow could be helpful for Cu-EDTA degradation,but the degradation rate would gradually reduce with the increase of Cu-EDTA initial concentration and PH value,the increased proportion of EDTA could do obvious inhibiting effect on the removal of Cu-EDTA whereas the increased proportion of Cu²⁺is helpful for Cu-EDTA removal,adding Cl^-could accelerate the degradation and adding NO₃^-,SO₄^2-could play first accelerating later inhibiting effect,and CO₃^2-could clearly inhibit the degradation of Cu-EDTA.（2）Add reactive radical scavenger to discuss what contribution and functional rules active matter does to the degradation of Cu-DETA.It is found that:when p-benzoquinone and isopropanol are added into the system the removal rate of Cu-EDTA reduce by 52.5%and59%respectively,the ion chromatography,three fluorescence and liquid chromatography data shows DBD efficient for the removal of Cu-DETA meanwhile also proves intermediate is produced during the process and Cu-DETA is partially mineralized into H₂O and CO₂,the capillary electrophoresis product diagram shows some possible products of Cu-EDTA degradation during DBD treatment,which are Cu-EDDA,Cu-IDA,Cu-NTA etc.（3）Use high pressure discharge system to treat Cu-EDTA simulative waste water for 10 min under the condition of 5 kV discharge voltage,160 L/h ventilation flow,0.3mmol/L Cu-EDTA as initial concentration and PH value as 4,the degradation rate of Cu-DETA is 87.3%.Increasing the discharge voltage is helpful for Cu-EDTA degradation,the degradation rate would gradually reduce with the increase of Cu-EDTA initial concentration and PH value,the increased proportion of EDTA could do obvious inhibiting effect on the removal of Cu-EDTA,when the proportion of Cu²⁺and EDTA is 1:4 the removal rate is38.5%in 10min,on contrast while proportion of Cu²⁺is increased the removal rate is 99%in60min,adding p-benzoquinone or isopropanol could both inhibit the degradation.