Fabrication and characterization of titanium-based lead dioxide electrode by electrochemical deposition with Ti4 O7 particles

Constant current-exponential attenuation mode: A non-traditional power supply mode for electrocatalytic oxidation

Low average current efficiency (ACE) and high energy consumption (EC) have seriously hindered the industrial development of electrocatalytic oxidation (ECO) technology. Timely adjustment of the current output according to the attenuation law of the organic pollutants concentration during the reaction process can help to solve the low electrical energy utilization problem at source. In this study, a non-traditional power supply mode with "constant current-exponential attenuation" (Mode CC-EA) was proposed and applied to intermittent ECO systems. The current is first output in a constant state and then attenuated exponentially according to the decreasing law of pollutants concentration, enabling efficient use of electrons at all stages of the reaction, resulting in increased degradation rates and ACE, and reduced EC. Acidic red G (ARG) was used as the target pollutant and the degradation effects of the traditional constant current mode (Mode CC), the direct exponential attenuation mode (Mode EA) and the Mode CC-EA were compared with different evaluation parameters. The results showed that the optimized Mode EA (n₄) and Mode CC-EA (70-n₁₁) degraded ARG with an ACE of 5.28 and 6.09%, respectively, which were 1.26 and 1.45 times higher than Mode CC (4.2%). At the same time, the EC were 0.36 and 0.27 kWh gCOD^-1, respectively, which were 12.2 and 34.2% lower than Mode CC (0.41 kWh gCOD^-1). The parameters of Mode CC-EA were further optimized and used for the degradation of three typical dye wastewaters, crystal violet (CV), methylene blue (MB) and methyl orange (MO), to investigate their general applicability. The results showed that the optimized Mode CC-EA achieved higher decolorization rates, chemical oxygen demand (COD) and total organic carbon (TOC) removal rates for the four wastewaters, including ARG, than Mode CC within 120 min for the same total input charge. The ACE of Mode CC-EA was on average 1.3 times higher than that of Mode CC, while the EC was on average 25.3% lower. Mode CC-EA achieves efficient use of electrical energy while ensuring the catalytic effect, which is of great application for the efficient treatment of dye wastewater and significance for the industrial development of ECO technology.

Progress in Preparation and Application of Titanium Sub-Oxides Electrode in Electrocatalytic Degradation for Wastewater Treatment

To achieve low-carbon and sustainable development it is imperative to explore water treatment technologies in a carbon-neutral model. Because of its advantages of high efficiency, low consumption, and no secondary pollution, electrocatalytic oxidation technology has attracted increasing attention in tackling the challenges of organic wastewater treatment. The performance of an electrocatalytic oxidation system depends mainly on the properties of electrodes materials. Compared with the instability of graphite electrodes, the high expenditure of noble metal electrodes and boron-doped diamond electrodes, and the hidden dangers of titanium-based metal oxide electrodes, a titanium sub-oxide material has been characterized as an ideal choice of anode material due to its unique crystal and electronic structure, including high conductivity, decent catalytic activity, intense physical and chemical stability, corrosion resistance, low cost, and long service life, etc. This paper systematically reviews the electrode preparation technology of Magnéli phase titanium sub-oxide and its research progress in the electrochemical advanced oxidation treatment of organic wastewater in recent years, with technical difficulties highlighted. Future research directions are further proposed in process optimization, material modification, and application expansion. It is worth noting that Magnéli phase titanium sub-oxides have played very important roles in organic degradation. There is no doubt that titanium sub-oxides will become indispensable materials in the future.

Evaluation of diclofenac degradation effect in "active" and "non-active" anodes: A new consideration about mineralization inclination

This work investigates the electrochemical oxidation (EO) of diclofenac (DCF) in water with Ti/Ti₄O₇, Ti/Ru-Ir, Ti/Sb-SnO₂ and Ti/PbO₂ electrodes. Scanning electron microscope and X-ray diffraction results suggest that Ti/Ti₄O₇ has porous stacked surface morphology and Ti/Sb-SnO₂ possesses the smallest grain size. Linear sweep voltammetry test results indicate that PbO₂ has the highest oxygen evolution potential, while Ti/Ti₄O₇ and Ti/Ru-Ir show better oxygen evolution activity. DCF degradation results reveal that PbO₂ possessed the highest DCF removal (R_DCF = 99.2%) and chemical oxygen demand (COD) removal (R_COD = 97.0%), the fastest COD degradation rate (k = 0.0275 min^-1, R² = 0.964), the lowest specific energy consumption (EC_DCF = 1.81 kWh^.g DCF^-1, EC_TOC = 6.90 kWh^.g TOC^-1). The toxicity variation of DCF during EO process on PbO₂ is rise first and then to fall. Considering the differences of the four electrodes in residual, conversion and mineralization aspects, mineralization selectivity (MS) was proposed to estimate the mineralization inclination of electrodes during EO process, and PbO₂ displays the strongest mineralization inclination (MS = 0.594). In addition, the possible degradation pathway of DCF on PbO₂ electrode indicates a composite behavior of conversion and mineralization. All of them above indicate the promising application potential of PbO₂ in lower concentration pharmaceuticals and personal care products wastewater treatment. Moreover, MS could be employed as a supplementary index to assess the different inclinations of this composite behavior on various electrodes used for electrochemical treatment of organics in later studies.