阴阳极协同作用下对硝基苯酚的电催化降解

利用线性扫描伏安法和恒电流电解法研究了Ti/PbO2电极对于对硝基苯酚（PNP）降解的电催化活性，通过对阳极过程和阴极过程中对硝基苯酚及其降解中间产物的液相色谱测定，研究了阴阳极协同作用下对硝基苯酚电催化降解的历程。 结果表明，Ti/PbO2电极能够有效地电催化降解水溶液中的对硝基苯酚，在35 ℃，初始浓度为1 mmol/L的对硝基苯酚水溶液，恒定电流密度40×10-3 A/cm2，电解240 min，对硝基苯酚转化率为98.6%。 对硝基苯酚电催化氧化降解要经历生成对苯二酚、邻苯二酚、对苯醌、丁烯二酸和草酸，最终变成二氧化碳和水的反应历程，其中对苯二酚为第一步反应的主产物，对苯醌转化为丁烯二酸和丁烯二酸转化为草酸这两步反应是阳极氧化过程的速率控制步骤。 对硝基苯酚在阴极上发生还原反应，还原产物为对氨基苯酚（PAM）。 在无隔膜电解槽中，由于阴极还原产物对氨基苯酚很容易到阳极上发生氧化反应，阴阳两极产生协同作用，因而加速了对硝基苯酚的降解反应。

Electrocatalytic Degradation of p-Nitrophenol Affected by the Synergsic Effect of Cathode and Anode

The electrocatalytic activity of Ti/PbO2 anode for degradation of p-nitrophenol was studied with linear sweeping voltammetry and galvanostatic electrolysis. The electrocatalytic degradation pathway of p-nitrophenol was explored by HPLC analysis of the reaction mixture in the anodic oxidation and cathodic reduction processes. The results indicate that Ti/PbO2 electrode can electrocatalyze the degradation of p-nitrophenol effectively. The conversion of the 1.0 mmol/L p-nitrophenol achieved 98.6% when the electrolysis was carried out for 240 min with a constant current of 40×10-3 A/cm2 at 35 ℃. The pathway of the electrocatalytic oxidation degradation of p-nitrophenol is p-nitrophenol → hydroquinone and pyocatechol → benzoquinone → maleic acid → oxalic acid → CO2 and H2O. The main product of the first step is hydroquinone. The conversions of benzoquinone to maleic acid and maleic acid to oxalic acid are the rate determining steps of anodic oxidation process. The p-nitrophenol can be reduced at the cathode. The reduction products include p-aminophenol. In an electrolytic cell without diaphragm, the cathodic reduction product, p-aminophenol, can be oxidated easily at the anode. The synergsic effect of the cathode and anode speeds up the degradation of p-nitrophenol in an undivided electrolytic cell compared to an electrolytic cell with diaphragm.