Corresponding Author

Yan-He Han(hanyanhe@bipt.edu.cn)


In the traditional Ti/β-PbO2 electrode, the crystal lattice difference between β-PbO2 and Ti matrix is large, and the prepared electrode is easy to fall off and has a short service life. It needs to be modified in actual use. Based on the advantages of α-PbO2 material and Ag material in terms of adhesion and conductivity, respectively, the above two materials are selected as the intermediate layer of Ti/β-PbO2 electrode to improve electrode performance. In this paper, by preparing Ti/α/β-PbO2 and Ti/Ag/β-PbO2 electrodes with different intermediate layers, the superiority and feasibility of electrocatalytic oxidation technology for rapid determination of organic matter (COD) content in simulated glucose wastewater were investigated. Firstly, the properties of the two electrodes were evaluated by scanning electron microscopy (SEM) and X-ray diffraction (XRD) to characterize the surface morphology and crystal structure of the electrodes, respectively. The electrode surfaces of Ti/α/β-PbO2 and Ti/Ag/β-PbO2 had no other granular crystal bare leakage, and their crystal arrangement was relatively compact. Compared with Ti/Ag/β-PbO2, the crystal structure of Ti/α/β-PbO2 electrode surface was more uniform and the grain size was smaller. Secondly, a series of electrochemical performance tests were carried out on the two electrodes by employing linear scanning voltammetry (LSV), Tafel curve analysis, cyclic voltammetry (CV) and AC impedance spectroscopy. The results show that the crystal structure of Ti/α/β-PbO2 electrode surface was more uniform, and the grain size was smaller, and the electroactive surface area was larger. The oxygen evolution potential of Ti/α/β-PbO2 electrode was 1.77 V, which provides a good condition for the formation of ·OH. In Tafel and CV tests, the exchange current density i0 and the specific capacitance CP of Ti/α/β-PbO2 electrode were 0.0995 A·cm-1 and 0.004098 F·cm-1, respectively, which are higher than those of Ti/Ag/β-PbO2 electrode, indicating that Ti/α/β-PbO2 electrode has excellent corrosion resistance and electron releasing ability, Finally, the Ti/α/β-PbO2 electrode was selected as a working electrode. The results show that the optimum conditions for the determination of COD by Ti/α/β-PbO2 electrode were as follows: the oxidation potential 1.30 V, electrolysis time 150 s, electrolyte concentration 0.03 mol·L-1 sodium nitrate (NaNO3). The correlation coefficient of COD measured by electrochemical method and colorimetric digestion method reached 0.9909, and it had good reproductivity and correlation. The detection range of COD was 0 mg·L-1 ~ 500 mg·L-1, which can replace the standard potassium dichromate method within the error allowable range, and provide reference value for the realization of rapid online COD detection. In follow-up studies, actual water samples such as surface water or sewage plant effluent will be compared with the colorimetric digestion method, and attention will be paid to the sensitivity of the electrode after multiple cycles of use.

Graphical Abstract


lead dioxide electrode, COD detection, electrocatalytic oxidation, preparation and characterization of electrode

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