介质阻挡放电等离子体处理酸性大红GR废水

DEGRADATION OF ACID SCARLET GR WASTEWATER BY DIELECTRIC BARRIER DISCHARGE

采用一种以待处理废水为接地极的介质阻挡放电反应器,对模拟酸性大红GR废水进行降解试验,考察了峰值电压、放电频率、放电间距、作用时间及溶液初始浓度等因素对酸性大红GR降解效果的影响,并对降解机理进行了初步探讨。试验结果表明,在废水初始质量浓度为30 mg/L,pH=2,放电间距6 mm,放电电压8 kV,放电频率10 kHz的条件下,放电处理20 min后脱色率达到76.4%;向反应体系中加入Fe2+有利于提高染料废水的脱色效果,溶液中Fe2+浓度为0.48 mmol/L时,放电处理20 min后脱色率达到92.1%。废水脱色率随处理时间的延长而提高,COD的变化则呈现上升-下降-上升-下降的趋势。酸性大红GR废水经放电处理后的中间产物主要为甲酸、乙酸、苯、对苯二酚、1-萘醌、6-萘酚、邻苯二甲酸(酐)、对羟基苯甲酸等,表明酸性大红GR分子上的C-N键断裂后,苯环在.OH的攻击下开环。降解产物中存在少量的羟基苯胺和对硝基苯胺,表明有少部分酸性大红GR的降解是通过N=N的断裂开始的。

A new-style dielectric barrier discharge（DBD） reactor,in which the flowing wastewater was used as the ground plate,was used to degrade the simulative acid scarlet GR wastewater.The factors affecting the degradations of organic pollutant,such as the peak voltages,the voltage frequencies,the distance between the two plate electrodes,the reaction time and the initial solution concentrations,were studied.Farther more,the possible mechanism of degradation of acid scarlet GR was proposed.The results showed that,the decolorizationrate after 20 min DBD decomposition was up to 76.4% with 2.0 initial pH,30 mg/L initial concentration,8 kV peak pulse voltage,10 kHz pulse repetitive,6 mm discharge distance.The Fe2＋ ion could effectively enhance decolorization rate.Under the same conditions as above,the decolorization rate could be increased to 92.1% with 0.48 mmol/L Fe2＋ ion being added.The decolorization rate was increased with the treatment time.The variation of COD was rise-down-rise-down during the degradation process.The C-N chemical bond and the pyridiner-ing of acid scarlet GR molecule were destructed by the hydroxyl radical,which produced some intermediate products,such as methane acid,acetic acid,benzene,hydroquinone,naphth-oquinone,6-naphthalene,phthalic acid（anhydride）,p-hydroxybenzoic acid etc.Some p-hydr-oxyaniline and p-nitroaniline among the intermediates showed that some acid scarlet GR were decomposed begin with the break of N=N.