Influence of the Pt nanoscale interlayer on stability and electrical property of Ti/Pt/Sb-SnO2 electrode: A synergetic experimental and computational study

Advances on electrochemical disinfection research: Mechanisms, influencing factors and applications

Disinfection, a vital barrier against pathogenic microorganisms, is crucial in halting the spread of waterborne diseases. Electrochemical methods have been extensively researched and implemented for the inactivation of pathogenic microorganisms from water and wastewater, primarily owing to their simplicity, efficiency, and eco-friendliness. This review succinctly outlined the core mechanisms of electrochemical disinfection (ED) and systematically examined the factors influencing its efficacy, including anode materials, system conditions, and target species. Additionally, the practical application of ED in water and wastewater treatment was comprehensively reviewed. Case studies involving various scenarios such as drinking water, hospital wastewater, black water, rainwater, and ballast water provided concrete instances of the expansive utility of ED. Finally, coupling ED with other technologies and the resulting synergies were introduced as pivotal foundations for subsequent engineering advancements.

Mechanism of highly efficient electrochemical degradation of antibiotic sulfadiazine using a layer-by-layer GNPs/PbO2 electrode

A PbO₂ electrode integrating electrocatalytic and adsorptive functions was successfully fabricated by embedding layer-by-layer graphene nanoplatelets (GNPs) into β-PbO₂ active layer (GNPs/PbO₂) and employed as anode for high-efficient removal of sulfadiazine (SDZ). In electrochemical degradation experiments, SDZ was quickly enriched on the surface of GNPs/PbO₂ film via adsorption and then oxidized by ⋅OH in-site. In terms of the electrocatalytic performance and adsorption of electrode, the optimal electrodeposition time for each β-PbO₂ outer layer was 4 min (GNPs/PbO₂-4). Compared with conventional PbO₂ electrode, the layer-by-layer GNPs resulted in the smaller crystal size and denser surface of PbO₂ electrode, thus facilitating the generation of active oxygen species. At the same time, the specific surface area, oxygen evolution potential (OEP) of the anode were enhanced and the charge-transfer resistance was reduced. For GNPs/PbO₂-4 anode, the optimal conditions of electrochemical oxidation of SDZ were identified as initial pH 9, 50 mg/L of SDZ and 20 mA/cm² of current density using response surface methodology (RSM), 98.15% of SDZ could be removed in this case. The contribution of radical oxidation and non-radical oxidation to SDZ removal was about 79% and 21%, respectively. Moreover, the reaction pathways of SDZ on the GNPs/PbO₂-4 electrode involving hydroxylation, radical reaction and ring cleavage were speculated. Finally, the continuous SDZ degradation and accelerated service lifetime test suggested that the GNPs/PbO₂-4 electrode was shown to be stable and repeatable, and the Pb²⁺ concentration was measured to ensure the safety of the treated solution. Consequently, the above findings provide an innovative way to design and prepare an effective and stable PbO₂ electrode for electrochemical degradation of antibiotic wastewater.

Application of lead oxide electrodes in wastewater treatment: A review

Electrochemical oxidation (EO) based on hydroxyl radicals (·OH) generated on lead dioxide has become a typical advanced oxidation process (AOP). Titanium-based lead dioxide electrodes (PbO₂/Ti) play an increasingly important role in EO. To further improve the efficiency, the structure and properties of the lead dioxide active surface layer can be modified by doping transition metals, rare earth metals, nonmetals, etc. Here, we compare the common preparation methods of lead dioxide. The EO performance of lead dioxide in wastewater containing dyes, pesticides, drugs, landfill leachate, coal, petrochemicals, etc., is discussed along with their suitable operating conditions. Finally, the factors influencing the contaminant removal kinetics on lead dioxide are systematically analysed.

Facile synthesis of highly active Ti/Sb-SnO2 electrode by sol-gel spinning technique for landfill leachate treatment

Highly active Ti/Sb-SnO₂ electrodes were fabricated using sol-gel spin coating procedure, which exhibited a rough, uniform and multilayer coating structure. The effects of different Sb-SnO₂ film layers on the physiochemical, electrochemical properties and pollutant degradability of electrodes and the mechanism were evaluated on a systematic basis. The electrodes with more active layers exhibited higher electro-catalytic performance. Upon exceeding 8 layers, the promotion effect of the coating was reduced. Considering various factors, this paper recommends preparing Ti/Sb-SnO₂ electrodes coated with 8 layers to obtain higher electro-catalytic ability in landfill leachate treatment. The specific number of coating layers should be determined according to the electrode requirements. This work provided a theoretical basis and technical support for the preparation of Ti-SnO₂ electrodes with high electro-catalytic activity and stability, while it still remains a great challenge to achieve an excellent balance between performance and stability before Ti/Sb-SnO₂ electrodes can be implemented on a large scale in wastewater treatment.

Preparation of Ti/SnO2-Sb/Rare Earth Electrodes Containing Different Contents of Ni Intermediate Layer for Efficient Electrochemical Decolorization of Rhodamine B

Water contamination by dyes discharged from many industries is an environmental issue of great matter. Electrochemical oxidation is an advanced approach for wastewater treatment. In this study, the composite electrodes of Ti/SnO2-Sb-Ni/rare earth have been modified using rare earth elements (Re) Gd, Ce, Eu, and Er and various molar ratios of tin and nickel intermediate layer, and their electrochemical oxidation effects were scrutinized. To analyze the decolorization performance of the electrodes, Rhodamine B (RhB) dye was utilized as a target pollutant. Accelerated life testing indicated that the longer service life could be observed in Ni (3.5%)/Re and Ni (5%)/ Re electrodes compared with other modified Ni (0%, 1%, and 2%)/Re electrodes. Compared with the color removal efficiencies of the Ni (2%)/Re electrodes, the decolorization rate of 90% after treatment for 60 min and the low energy consumption of 3.621 kW h·m−3 can be achieved at the Ni (2%)/Gd electrode under the experimental condition of 100 mg·L−1 RhB. The best decolorization rate was observed at the Ni (2%)/Re electrodes among other Ni and no adding Ni-doped Re electrodes. The characterization of the electrodes was described, consisting of surface morphology, oxygen evolution potential, and a crystallographic and elemental combination of the coatings.

Characterization and comparison of Ti/TiO2-NT/SnO2-SbBi, Ti/SnO2-SbBi and BDD anode for the removal of persistent iodinated contrast media (ICM)

In this study, we investigated the impact of a TiO₂ nanotube (NT) interlayer on the electrochemical performance and service life of Sb and Bi-doped SnO₂-coatings synthesized on a titanium mesh. Ti/SnO₂-SbBi electrode was synthetized by a thermal decomposition method using ionic liquid as a precursor solvent. Ti/TiO₂-NT/SnO₂-SbBi electrode was obtained by a two-step electrochemical anodization, followed by the same process of thermal decomposition. The synthesized electrodes were electrochemically characterized and analyzed by scanning electron microscopy and energy dispersive X-ray spectroscopy. Terephthalic acid (TA) experiments showed that Ti/SnO₂-SbBi and Ti/TiO₂-NT/SnO₂-SbBi electrodes formed somewhat higher amounts of hydroxyl radicals (HO) compared with the mesh boron doped diamond (BDD) anode. Electrochemical oxidation experiments were performed using iodinated contrast media (ICM) as model organic contaminants persistent to oxidation. At current density of 50 A m^-2, BDD clearly outperformed the synthesized mixed metal oxide (MMO) electrodes, with 2 to 3-fold higher oxidation rates observed for ICM. However, at 100 and 150 A m^-2, Ti/SnO₂-SbBi had similar performance to BDD, whereas Ti/TiO₂-NT/SnO₂-SbBi yielded even higher oxidation rates. Disappearance of the target ICM was followed by up to 80% removal of adsorbable organic iodide (AOI) for all three materials, further demonstrating iodine cleavage and thus oxidative degradation of ICM mediated by HO. The presence of a TiO₂ NT interlayer yielded nearly 4-fold increase in anode stability and dislocated the oxygen evolution reaction by +0.2 V. Thus, TiO₂ NT interlayer enhanced electrode stability and service life, and the electrocatalytic activity for the degradation of persistent organic contaminants.

Preparation of a SnO2–Sb electrode on a novel TiO2 network structure with long service lifetime for degradation of dye wastewater

Developing effective electrodes with long service lifetime for electrochemical degradation of dyes is of paramount importance for their practical industrial applications. We constructed a novel SnO₂–Sb electrode (Ti/TiO₂-NW/SnO₂–Sb electrode) based on a uniform TiO₂ network structure decorated Ti plate (Ti/TiO₂-NW) for a long-term electrocatalytic performance. The SnO₂–Sb coating layer on this electrode was grown on the Ti/TiO₂-NW by pulse electrodeposition. The introduction of the three-dimensional TiO₂-NW enhances the bonding strength between the Ti substrate and the SnO₂–Sb surface coating. An accelerated life test shows that the service life of Ti/TiO₂-NW/SnO₂–Sb electrode is 11.15 times longer than that of the traditional Ti/SnO₂–Sb electrode. The physicochemical properties of the electrodes were characterized through SEM, EDS, XRD and HRTEM. In addition, through LSV, EIS, CV and voltammetric charge analysis, it is found that compared with the traditional electrode, the Ti/TiO₂-NW/SnO₂–Sb electrode possesses a higher oxygen evolution potential, a lower charge transfer resistance and a larger electrochemical active surface area. Besides, this novel electrode also exhibits an outstanding electrocatalytic oxidation ability for degradation of acid red 73 in simulated sewage. After a 5 hours' test, the removal efficiency of acid red 73 and the COD reached 98.6% and 71.8%, respectively, which were superior to those of Ti/SnO₂–Sb electrode (89.1% and 58.8%). This study highlights the excellent stability of the Ti/TiO₂-NW/SnO₂–Sb electrode and provides an energy-efficient strategy for dye degradation.

A novel TiO₂ network structure modified SnO₂–Sb electrode has been prepared by electrodeposition with long service lifetime and low energy consumption.