不同涂层电极和抑制剂对电化学氧化降解苯酚的影响

采用热分解法和电沉积法2种工艺制得4个二氧化铅电极,用扫描电镜（SEM）观察了电极表面形貌.以水杨酸(2-HBA)为捕获剂,用高效液相色谱仪测定羟基自由基与水杨酸的羟基化产物2,5-二羟基苯甲酸(2,5-DHBA)的量作为产生的羟基自由基的浓度.通过羟基自由基的浓度的测定和苯酚的降解,研究了不同涂层电极和抑制剂对电化学氧化对苯酚降解的影响.热分解电极、无掺杂电极、掺铋电极和掺镧电极产生羟基自由基的最大浓度分别为0.781、1.048、1.838、2.044 μmol/L,以这4个电极为阳极对苯酚进行电解, 1.5　h苯酚去除率分别为87.30%、93.55%、97.95%、98.70%,5　h　TOC去除率分别为86.75%、94.26%、98.53%、99.60%;以掺镧电极为阳极,加入抑制剂CO^2-₃、PO^3-₄、CH₃ＣＯＯ^-产生的羟基自由基的最大浓度分别为无检出、0.170 μmol/L、0.270 μmol/L,对苯酚进行电解,5 h苯酚去除率分别为99.06%、99.98%、99.79%.电沉积法制得电极对苯酚的降解效果优于热分解法制得的电极,而掺杂的电极优于无掺杂的电极,掺镧电极对苯酚降解效果最好,抑制剂CO^2-₃、PO^3-₄、CH₃ＣＯＯ^-存在时会对苯酚的降解起到阻碍作用,CO^2-₃阻碍作用最强.不同制备方法和掺杂不同添加剂制得的电极的催化性能不同,对苯酚的降解效果也不同;羟基自由基的浓度越大,苯酚的降解效果越好,抑制剂捕获了产生的羟基自由基,不利于苯酚的降解.

Impact on Electrochemical Degradation of Phenol with Different Coated Electrodes and Inhibitors

Four lead dioxide electrodes on Ti substrates were prepared by thermal-deposition and electro-deposition. Scanning electron microscopy (SEM) was used to study the characterization of surface of electrodes. High performance liquid chromatograph was applied to detect the concentration of the aromatic hydroxylation 2,5-DHBA to determine the amount of .OH with 2-HBA as the capture matter. This study investigated effect of different coated electrodes and inhibitors on degradation of phenol by hydroxyl radicals generated by electrolysis in terms of the measurement of hydroxyl radicals and degradation of phenol. The experimental results show that the highest concentration of hydroxyl radicals generated by thermal-deposition, electro-deposition mingled with nothing, electro-deposition mingled with Bi or La were 0.781 micromol/L, 1.048 micromol/L, 1.838 micromol/L, 2.044 micromol/L, respectively. When phenol was electrolyzed by electrodes prepared by the four electrodes, the removal efficiencies of phenol at 1.5 h were 87.30%, 93.55%, 97.95% and 98.70%, and TOC removal efficiencies at 5 h were 86.76%, 94.26%, 98.53% and 99.60%, respectively. The highest concentration of hydroxyl radicals when CO3(2), PO4(3) or CH3COO-existed was no detected, 0.170 micromol/L, 0.270 micromol/L, and the removal efficiencies of phenol were 99.06%, 99.98% and 99.79%, respectively. The degradation of phenol with electrodes prepared by electro-deposition is better than the electrodes prepared by thermal-deposition, and the electrode mingled with La is better than the electrode mingled nothing and with Bi. The electrode mingled with La is the best. The degradation of phenol is inhibited when CO3(2-), PO4(3-) or CH3COO- exists, and the inhibiting effect of CO3(2-) is the strongest. The catalytic characteristics of electrodes and degradation of phenol by them are different when the electrodes are prepared by different methods or with different additives; the higher the concentration of hydroxyl is, the better the degradation of phenol is. Inhibitors capture hydroxyl radicals, and isn't in favor of degradation of phenol.