Institute of Chemistry of Araraquara, Department of Analytical Chemistry, UNESP, Rua Francisco Degni, 55, 14800-900 Araraquara, SP, Brazil.
Institute of Chemistry of Araraquara, Department of Analytical Chemistry, UNESP, Rua Francisco Degni, 55, 14800-900 Araraquara, SP, Brazil.
Chemosphere. 2015 Oct;136:63-71. doi: 10.1016/j.chemosphere.2015.04.042. Epub 2015 May 15.
In this study, a coupled photoelectrocatalytic/photoelectro-Fenton reactor was designed to enhance the degradation efficiency of organic pollutants and tested using the azo dye Orange G as a model compound. Pt-decorated TiO2 nanotubes were used as a photoanode with an air-diffusion polytetrafluoroethylene cathode for H2O2 generation. The sum of individual effects of coupling the photoelectrocatalytic and photoelectro-Fenton processes was evaluated as a function of the decolorization and mineralization of Orange G solutions. The dye solutions were only completely decolorized in more acidic conditions (pH 3.0). The mineralization of the Orange G solutions increased in the sequence photoelectrocatalytic<electro-Fenton<coupled photoelectrocatalytic/photoelectro-Fenton due to the gradual increase in the production of OH radicals. Total organic carbon reductions of 80% for photoelectrocatalysis, 87% for electro-Fenton and 97% for the coupled processes were obtained when using an applied electric charge per unit volume of electrolyzed solution of 200 mA h L(-1). The Orange G decays for all treatments followed pseudo-first-order kinetics, suggesting the attack of a constant concentration of OH radicals. Aromatics such as naphthalenic and benzenic compounds were formed as by-products and were identified using LC-MS/MS analysis. In addition, the generated aliphatic acids were identified using ion-exclusion high-performance liquid chromatography. The final by-products of oxalic and formic acid were identified as ultimate by-products and formed Fe(III) complexes that were rapidly mineralized to CO2 by UV-Vis irradiation. Then, according to the identified oxidation by-products, a plausible pathway was proposed for the degradation of Orange G dye by the coupled process.
在这项研究中，设计了一种光电催化/光电芬顿偶联反应器，以提高有机污染物的降解效率，并使用偶氮染料橙 G 作为模型化合物进行了测试。Pt 修饰的 TiO2 纳米管用作光阳极，带有空气扩散聚四氟乙烯阴极用于 H2O2 的生成。作为单独影响的总和，评估了光电催化和光电芬顿过程偶联对橙 G 溶液的脱色和矿化的影响。只有在更酸性的条件下（pH 3.0），染料溶液才完全脱色。由于 OH 自由基的逐渐增加，橙 G 溶液的矿化顺序为光电催化<电芬顿<光电催化/光电芬顿偶联。当使用单位体积电解溶液的施加电荷量为 200 mA h L(-1) 时，光电催化得到 80%的总有机碳去除率，电芬顿得到 87%，偶联过程得到 97%。所有处理的橙 G 衰减均遵循准一级动力学，表明 OH 自由基的恒定浓度的攻击。使用 LC-MS/MS 分析鉴定了萘和苯类化合物等芳香族化合物作为副产物。此外，使用离子排斥高效液相色谱法鉴定了生成的脂肪酸。草酸和甲酸等最终副产物被鉴定为最终副产物，并形成 Fe(III)配合物，通过 UV-Vis 辐射迅速矿化为 CO2。然后，根据鉴定的氧化副产物，提出了一种通过偶联过程降解橙 G 染料的可能途径。
