等离子体制取羟自由基降解苯酚溶液及其历程的UV研究

研究了利用强电离放电产生等离子体方法制取羟基自由基氧化降解高浓度苯酚废水。当羟基自由基浓度达到1 037 mg·L-1时，初始浓度为1 215 mg·L-1的废水降解率达99.11%；初始浓度为8 853 mg·L-1的废水苯酚浓度下降到6 250 mg·L-1,1 mg羟基自由基可处理苯酚2.5 mg。在同样羟自由基浓度下，苯酚初始浓度越小，去除率越高；但初始浓度越高，处理的绝对量越大。阐述并解释了不同降解阶段废水pH值、电导率与羟基自由基浓度变化的关系。随着羟自由基浓度的增大，废水酸碱性由接近中性逐渐转为酸性，浓度越大，酸性越强；继续增大羟自由基浓度，变化渐趋平缓。随着羟自由基的通入，电导率有一个微小的降低阶段然后开始上升，说明苯酚不断的被氧化为有机酸。通过紫外图谱和色谱分析了降解中间产物，表明氧化初始阶段邻苯二酚、对苯二酚和苯醌是其中重要的化合物。

Study on the Degradation of Phenol Wastewater Using Hydroxyl Radical Produced by Plasma and the Course by UV Spectra

The phenol wastewater with high concentration was treated by hydroxyl radical produced by a strong ionization discharge plasma in the present article. Salicylic acid used as molecular probe to determine the concentration of hydroxyl radical. The phenol elimination efficiency of wastewater whose initial concentration was 1 21 5 mg·L-1 could reach 99.11% when the concentration of hydroxyl radical was 1 037 mg·L-1; while the initial concentration of 8 853 mg·L-1 of phenol wastewater dropped to 6 250 mg·L-1 under the same conditions, that is, 1 mg hydroxyl radicals could oxidize 2.5 mg of phenol. The smaller the initial phenol concentration, the higher the removal. However, the higher the initial concentration, the greater the absolute quantity of treatment. And the relation between the changes including pH value and the conductivity and the concentration of hydroxyl radical was stated and explained. With the concentration of hydroxyl radicals increasing, the pH value of wastewater changed from close to neutral to acidity gradually. The higher the concentration of hydroxyl radical, the stronger the acidity of wastewater. When continuing the increase in the concentration of hydroxyl radical, the change began to smooth. With the addition of hydroxyl radical, as is different from other phenomena, there was a tiny descending stage before ascending as shown on the conductivity curve, indicating that phenol had been oxidized and generated the organic acids continuously. Catechol, hydroquinone and benzoquinone are the important compounds of the intermediate products as shown by the analysis of UV spectra and chromatography. The final UV spectra curve indicated that there were little organic compounds containing conjugated structure in the treated wastewater.