Three-dimensional electrochemical process for wastewater treatment: A general review

In this work, a convergent paired electrochemical method was used for the mineralization of p-dinitrobenzene (p-DNB) over a Ti/SnO2-Sb/β-PbO2 anode. This anode shows high overvoltage for oxygen evolution, long service lifetime and excellent electrocatalytic degradation efficiency. The influence of several operating parameters on the conversion paired electrocatalytic degradation of p-DNB and COD removal efficiency has been examined. The results showed that the degradation and COD removal of p-DNB reached up to 100% and 98%, respectively. The most important part of this study is to propose a novel mechanism for electrochemical degradation of p-DNB. We discovered that both anodic and cathodic reactions are responsible for mineralization of p-DNB. Accordingly, we propose a convergent paired electrocatalytic degradation mechanism based on the reduction of p-DNB at the cathode and oxidation of cathodically generated p-diaminobenzene at the anode surface for electrochemical mineralization of p-DNB.

Convergent paired electrocatalytic degradation of p-dinitrobenzene by Ti/SnO2-Sb/β-PbO2 anode. A new insight into the electrochemical degradation mechanism

Chemical oxygen demand (COD) is a critical analytical parameter for water quality assessment. COD represents the degree of organic pollution in water bodies. However, the standard analytical methods for COD are time-consuming and possess low oxidation efficiency, chloride interference, and severe secondary pollution. Works performed during the last two decades have resulted in several technologies, including modified standard methods (e.g., microwave-assisted method) and new technologies or methods (e.g., electro- and photo-oxidative methods based on advanced oxidation processes) that are less time-consuming, environment friendly, and more reliable. This review is devoted in analyzing the technical features of the principal methods described in the literature to compare their performances (i.e., measuring window, reliability, and robustness) and identify the advantages and disadvantages of each method.

Analytical Approaches for Determining Chemical Oxygen Demand in Water Bodies: A Review.

Chemical oxygen demand: Historical perspectives and future challenges

The effects of sp2-bonded carbon impurities on the electrochemical properties of boron-doped diamond were investigated in moderately ([B]   1021 cm−3) boron doping levels. Significant influences of sp2-bonded carbon impurities, which show glassy carbon-like electrochemical properties after anodic oxidation, were observed in heavily boron-doped diamond. This indicated that the significant effects of enhanced adsorption properties were possibly caused by surface relaxation of the strains induced by heavy boron doping and sp2-bonded carbon impurities. On the other hand, their durability was still similar to diamond electrodes rather than glassy-carbon electrodes because of the low fraction of sp2-bonded carbon impurities. Such “active” diamond electrodes are much less suitable for wastewater treatment than ordinary diamond electrodes due to a different oxygen-evolution mechanism. On the other hand, “active” BDD electrodes have a much higher efficiency for electrochemical ozone production than other BDD electrodes. The electrode properties of BDD can be designed by controlling the boron doping level and introducing the sp2-bonded carbon impurities. The guidelines proposed in this study can be used effectively to design electrodes according to their individual application, such as for use as electrochemical sensors, in wastewater treatment or electrochemical ozone production.

Tailored design of boron-doped diamond electrodes for various electrochemical applications with boron-doping level and sp2-bonded carbon impurities

A simple, environmentally friendly and continuous flow method was developed for the determination of COD based on a flow injection analysis (FIA) system, in which a BDD electrode was employed as the detecting element. The structure and the electrochemical behavior of BDD were investigated by a scanning electron microscope, Raman spectroscopy, and cyclic voltammetry, respectively. The results demonstrated that the high-quality BDD film prepared here was suitable to be used as an electrode, with which the COD measurement could be conducted. The effect of several important experimental parameters, such as applied potentials, pH, flow rates, and supporting electrolyte concentrations, on the analytical performance was investigated. Under optimized testing conditions, the proposed method was successfully applied in the COD analysis of synthetic samples. The linear range and the detection limit were 2−175 and 1 mg L−1, respectively. In addition, the COD values determined by the proposed method compared well with...

Flow Injection Analysis of Chemical Oxygen Demand (COD) by Using a Boron-Doped Diamond (BDD) Electrode

A novel Ti/Sb–SnO 2 /PbO 2 composite electrode was fabricated for COD determination. The new electrode configuration improved the sensitivity of the amperometric method apparently. Effects of common experimental parameters, such as applied potential, pH and concentration of the electrolyte on its analytical performance were investigated. A linear range of 0.5–200 mg L −1 COD and a detection limit (a signal-to-noise ratio of 3) of 0.3 mg L −1 were achieved under optimized conditions. The experiments for detecting COD in model samples and real samples were carried out to evaluate the electrode's performance. The obtained results were in good agreement with those determined by the standard dichromate method, with a relative error less than 12%.

Sensitive amperometric determination of chemical oxygen demand using Ti/Sb–SnO2/PbO2 composite electrode

Boron-doped diamond micro-nano material with columnar array structure and preparation method thereof

The invention belongs to the technical field of environmental monitoring, relating to COD on-line monitoring device and method based on a boron-doped diamond membrane (BDD) electrode. The device comprises an electrochemical detecting system, current signal collecting and processing circuit, a pump valve power system and a pipeline. The BDD electrode is adopted for the working electrode, the areais 10-80 m2, electrolytes and deionized water for dilution are injected through a double-pump head peristaltic pump when the device is used for measuring, the pH value is 1-7 and the concentration is0.01-0.1 mol/L after mixing, the deionized water or standard solutions or water samples with the same volume as the total volume of an electrochemical reaction solution are injected through a single-pump head peristaltic pump, and the measuring precision is ensured. When a reference electrode is a silver/silver chloride electrode, the measuring voltage is 1.5-3.0 V, and the measuring time is 50-200 seconds. The device has the advantages of long service life of the electrode, no pollution, stable response signal, high response speed and small measuring error and is suitable for the COD measurement of various polluted water bodies, wherein the single-time measuring process only needs 5-10 minutes.

Chuanjun Ma

Papers

Flow Injection Analysis of Chemical Oxygen Demand (COD) by Using a Boron-Doped Diamond (BDD) Electrode

Sensitive amperometric determination of chemical oxygen demand using Ti/Sb–SnO2/PbO2 composite electrode

Boron-doped diamond micro-nano material with columnar array structure and preparation method thereof

Chemical oxygen demand (COD) on-line monitoring device and method based on boron-doped diamond membrane electrode

Electrochemical method for measuring permanganate index