亚氧化钛块体电极的电化学特性及其对几种工业有机废水的降解效能研究

Electrochemical Properties of Titanium Sub-Oxide Bulk Electrodes and Its Degradation Efficiency to Several Industrial Organic Wastewaters

摘要:

亚氧化钛电极Ti_nO_2n－1(4≤n≤10) 具有环境友好、导电性好、耐强酸强碱、析氧电位高等优异性能，在电催化氧化处理难降解有机废水领域中极具应用潜力。采用自制的亚氧化钛块体电极，研究该电极的电化学特性及其对多种难降解工业有机废水的降解效能，并表征该电极的组成和表面形貌。结果表明：该块体电极为表面多孔结构，电极表层的主相为Ti₄O₇，电极的粗糙系数约为500，能为电化学反应提供较大的活性比表面积；同时，其电化学电位稳定窗口可高达3.6 V，电化学交换电流密度为4.606×10^-2 mA?cm^-2，均高于DSA电极（2.3 V和1.861×10^-2 mA?cm^-2）；此外，该块体电极及DSA电极的电化学氧化降解亚甲基蓝（MB）的过程均符合准一级反应动力学方程，且反应动力学常数k_亚氧化钛=2.0 k_DSA。利用亚氧化钛块体电极对多种工业废水，如垃圾渗滤液、金属冶炼厂的残余液等样本进行了降解处理，上述废液的化学需氧量（COD_Cr）去除率均能达到90%以上，表明该电极装置能有效地处理难降解工业废水。

Abstract:

Titanium sub-oxide electrode materials （Ti_nO_2n－1， 4≤n≤10） has excellent properties of environmental friendliness， good conductivity， strong acid and alkali resistance， high oxygen evolution potential， and has great application potential in the field of electro-catalytic oxidation treatment of refractory organic wastewater. Using a self-made titanium oxide bulk electrode， the electrochemical properties of the electrode and its degradation efficiency to various refractory industrial organic wastewater were studied， and the composition and surface morphology of the electrode were also characterized. The results show that the bulk electrode has a surface porous structure， the main phase of the electrode surface is Ti₄O₇， and the electrode roughness coefficient is about 500， which can provide a large active specific surface area for electrochemical reactions. At the same time， its electrochemical potential stability window can be as high as 3.6 V， and the electrochemical exchange current density is 4.606 ×10^-2 mA?cm^-2， which are both higher than those of DSA electrodes （2.3 V and 1.861×10^-2 mA?cm^-2）. In addition， the electrochemical oxidative degradation of methylene blue （MB） at the bulk electrode and the DSA electrode conformed to the pseudo-first-order reaction kinetic equation， and the reaction kinetic constant k_Ti4O7=2.0 k_DSA. A variety of industrial wastewaters， such as landfill leachate， residual liquid from metal smelters， etc.， were degraded by using titanium oxide bulk electrodes. The chemical oxygen demand （COD_Cr） removal rate of the above-mentioned waste liquids can reach more than 90%， indicating that the electrode device can effectively treat these refractory real industrial wastewaters.