Ti/RuO2-SnO2-TiO2涂层电极电催化氧化苯酚废水研究

Electro-catalytic oxidation of phenolcontaining sewage by using the anodic coated electrode

采用热分解法将SnO2掺杂于RuO2-TiO2涂层中,制得性能高效的Ti/RuO2-SnO2-TiO2阳极氧化电极。以该自制电极为阳极、钛板为阴极构成电催化氧化体系,对模拟苯酚废水进行电催化氧化试验。利用高效液相色谱探讨了苯酚废水溶液在该体系中的电催化氧化反应历程,并推断出氧化降解途径。采用SEM和XRD表征电极涂层结构和形貌,循环伏安法测试电极电化学性能。通过单因素试验考察反应时间、电流密度（CD）、电极间距、Na2SO4电解质浓度、苯酚质量浓度、pH值五个因素对电催化氧化试验的影响,结果表明：在反应时间为240 min、电流密度为102.6 mA/cm-2、电极间距为1.5 cm、电解质浓度为0.5 mol/L、苯酚质量浓度为300 mg/L、pH=5的最佳试验条件下,苯酚的降解率达到98%以上,COD的去除率达到90%以上。

The present paper intends to introduce a kind of multilayer coated electrode endowed with high-catalytic performance in regard with its distinguished electrode materials so as to solve the water pollution problem caused by the organic refractory sewage.The author initiated the Ti/RuO2-SnO2-TiO2 anodic electrode through thermal decomposition with SnO2 doped on the RuO2-TiO2.The electro-catalytic oxidation system is consist of our selfprepared electrode as anode and the titanium plate as cathode in the phenol sewage,which serves as the treating object.By means of high performance liquid chromatography in different reaction time lengths,we have made an investigation of the electro-catalytic oxidation technical process of the phenol sewage and the pathway of the phenol degradation.The results of our investigation demonstrate that phenol is so susceptible as to attack the hydroxyl radical（·OH） in the solution.And,in turn,the following generation of catechol and hydroquinone can be continually oxidized to produce quinone,which can be followed by an open-loop reaction and lead to the appearance of the small molecules of carboxylic acid.At this,we have made an analysis of the local areas of Ti/RuO2-SnO2-TiO2 electrode by scanning the electronic microscope（SEM） and X-ray diffractometer（XRD） so as to trace and examine the surface morphology and the crystal phase composition of the electrode.The results of our investigation indicate that the surface of the electrode is covered with complex mud cracks and highly peculiar structures.And,later,we have further examined the connection situation between the electrode material and the phenol catalytic degradation.And,eventually,we have successfully obtained and determined the electrochemical properties of the electrode by using the cyclic voltammetry and disclosed the quasi-reversible behavior on the phenol at Ti/RuO2-SnO2-TiO2 electrode.In addition,we have also investigated and identified the effects of the reaction time,the current density（CD）,the electrode interval,the electrolyte concentration of Na2SO4,the phenol concentration itself and the pH value on the electro-catalytic oxidation experiment through a single factor experiment.The said electro-catalytic experiment indicates that the most available feasible conditions can be stated below：the reaction time：240 minutes;the current density（CD） ：102.6 mA/cm2;the electrode interval：1.5 cm;the electrolyte concentration：0.5 mol/L;the phenol concentration：300 mg/L,whereas the pH value should be set up at 5.With the above mentioned conditions prepared,it would be possible to increase the removing rate of phenol concentration and COD by as much as over 98%,90%,respectively.