硼掺杂金刚石膜电极电氧化降解对氯苯酚废水

Study on the Degradation of p-Chlorophenol by Electrochemical Oxidation Using Boron-Doped Diamond Film Electrode

采用循环伏安法研究了中性介质中对氯苯酚在硼掺杂金刚石(BDD)膜电极上的电氧化行为。提出了一种以BDD膜电极为阳极的电化学氧化降解对氯苯酚废水的新工艺,考察了阳极电流密度、对氯苯酚初始浓度、电解液初始pH、支持电解质浓度等工艺因素对电氧化降解效果的影响。结果表明:在阳极极化电位为1.4～1.6V(vs.SCE)时,对氯苯酚在BDD膜电极表面发生直接电氧化反应,生成易吸附的中间产物,导致电极活性降低;在阳极极化电位高于2.0V(vs.SCE)时,BDD膜电极能够良好地电氧化降解对氯苯酚溶液,该过程是通过直接电氧化过程与间接电氧化过程联合作用实现的。通过考察若干工艺因素对对氯苯酚电氧化降解效果的影响发现,较为理想的工艺参数组合为,阳极电流密度60mA·cm-2、支持电解质浓度10g·L-1、对氯苯酚初始浓度10mmol·L-1、电解液初始pH7。在该工艺条件下,COD去除率达到96.1%,平均电流效率为50.2%。高效液相色谱证实了BDD膜电极能有效地电氧化降解对氯苯酚。

The behavior of electrochemical oxidation of p-chlorophenol has been studied with boron-doped diamond（BDD） film electrode in neutral medium by cyclic voltammetry.A new technology for degradation of p-chlorophenol by electrochemical oxidation is proposed with BDD anode.The effects of technological parameters are investigated which include the anodic current density,the initial concentration of p-chlorophenol,the initial pH value and the concentration of supporting electrolyte.The results show that direct electro-oxidation reactions occur on BDD film electrode when the electrode is polarized at 1.4～1.6 V（vs.SCE）,which results in decrease of electrode activity due to the formation of the intermediate products on BDD surface.Nevertheless,while the electrode is polarized over 2.0 V（vs.SCE）,p-chlorophenol can be degraded successfully by electro-oxidation.The degradation is a combination of direct and indirect electro-oxidation.Through the study of this electro-oxidation degradation of p-chlorophenol,optimized technological parameters are obtained as following：the anodic current density is 60 mA·cm-2,the initial p-chlorophenol concentration is 10 mmol·L-1,the initial pH value is 7,supporting electrolyte concentration is 10 g·L-1.Under above optimized technological conditions,the removal of COD and the average current efficiency are 96.1% and 50.2% respectively.The results of high performance liquid chromatography（HPLC） detection confirm that p-chlorophenol can be degraded efficiently by electro-oxidation.