Comparison of electrocatalytic characterization of Ti/Sb-SnO2 and Ti/F-PbO2 electrodes

Catalytic electrodes' characterization study serving polluted water treatment: environmental healthcare and ecological risk assessment

Pesticide residues in the environment have irreparable effects on human health and other organisms. Hence, it is necessary to treat and degrade them from polluted water. In the current work, the electrochemical removal of the fenitrothion (FT), trifluralin (TF), and chlorothalonil (CT) pesticides were performed by catalytic electrode. The characteristics of SnO2-Sb2O3, PbO2, and Bi-PbO2 electrodes were described by FE-SEM and XRD. Dynamic electrochemical techniques including cyclic voltammetry, electrochemical impedance spectroscopy, accelerated life, and linear polarization were employed to investigate the electrochemical performance of fabricated electrodes. Moreover, evaluate the risk of toxic metals release from the catalytic electrode during treatment process was investigated. The maximum degradation efficiency of 99.8, 100, and 100% for FT, TF, and CT was found under the optimal condition of FT, TF, and CT concentration 15.0 mg L-1, pH 7.0, current density 7.0 mA cm-2, and electrolysis time of 120 min. The Bi-PbO2, PbO2, and SnO2-Sb2O3 electrodes revealed the oxygen evolution potential of 2.089, 1.983, 1.914 V, and the service lifetime of 82, 144, and 323 h, respectively. The results showed that after 5.0 h of electrolysis, none of the heavy metals such as Bi, Pb, Sb, Sn, and Ti were detected in the treated solution.

Preparation of Porous Ti/RuO2-IrO2@Pt, Ti/RuO2-TiO2@Pt and Ti/Y2O3-RuO2-TiO2@Pt Anodes for Efficient Electrocatalytic Decomposition of Tetracycline

Electrocatalytic oxidation (ECO) has attracted attention because of its high efficiency and environmental friendliness in water treatment. The preparation of anodes with high catalytic activity and long service lifetimes is a core part of electrocatalytic oxidation technology. Here, porous Ti/RuO₂-IrO₂@Pt, Ti/RuO₂-TiO₂@Pt, and Ti/Y₂O₃-RuO₂-TiO₂@Pt anodes were fabricated by means of modified micro-emulsion and vacuum impregnation methods with high porosity titanium plates as substrates. The scanning electron microscopy (SEM) images showed that RuO₂-IrO₂@Pt, RuO₂-TiO₂@Pt, and Y₂O₃-RuO₂-TiO₂@Pt nanoparticles were coated on the inner surface of the as-prepared anodes to form the active layer. Electrochemical analysis revealed that the high porosity substrate could result in a large electrochemically active area, and a long service life (60 h at 2 A cm^-2 current density, 1 mol L^-1 H₂SO₄ as the electrolyte, and 40 °C). The degradation experiments conducted on tetracycline hydrochloride (TC) showed that the porous Ti/Y₂O₃-RuO₂-TiO₂@Pt had the highest degradation efficiency for tetracycline, reaching 100% removal in 10 min with the lowest energy consumption of 167 kWh kg^-1 TOC. The reaction was consistent with the pseudo-primary kinetics results with a k value of 0.5480 mol L^-1 s^-1, which was 16 times higher than that of the commercial Ti/RuO₂-IrO₂ electrode. The fluorospectrophotometry studies verified that the degradation and mineralization of tetracycline were mainly ascribed to the •OH generated in the electrocatalytic oxidation process. This study thus presents a series of alternative anodes for future industrial wastewater treatment.

Electrocoagulation coupled with conductive ceramic membrane filtration for wastewater treatment: Toward membrane modification, characterization, and application

Membrane separation is an effective solution for pollutant removal, however, achieving high permeability and antifouling ability remains a pressing challenge for its widespread application. In this study, a novel method of coating flat ceramic membranes (CMs) with a conductive film (Sb-SnO₂) was developed to enhance the filtration and antifouling performance of CMs when the membrane filtration was coupled with electrocoagulation. After comparing the parameters, including the film sheet resistance and pure water flux, with those of other coating methods (i.e., gel coating and immersion hydrolysis), a well-fixed conductive coating with optimal permeability and stability was generated using spray pyrolysis with a substrate ceramic membrane surface temperature of 475 °C, precursor concentration of 0.5 M (calculate as SnO₂), and spraying amount of 50 mL (120 cm²), during membrane modification. Batch filtration experiments using wastewater from the mechanical industry demonstrated that the conductive ceramic membrane (CCM) cathode integrated with electrocoagulation at an electric field of 2.8 V/cm (3.0 mA/cm²) achieved permeate fluxes that were 0.34, 0.70, 0.75 and 1.41 times higher than those of sole CM separation after four cycles. Moreover, the membrane separation process was dominated by the standard pore-blocking model, and its correlation coefficient decreased with the exertion of the electric field, indicating that membrane filtration fouling changed from irreversible to reversible. This CCM combined with electrocoagulation exhibited significant potential for alleviating membrane fouling and widespread application, and could act as a promising technology for industrial wastewater treatment.

Optimized terbium doped Ti/PbO2 dimensional stable anode as a strong tool for electrocatalytic degradation of imidacloprid waste water

The presence of pesticides in water has emerged as a momentous environmental issue over the past decades. Herein, a terbium doped Ti/PbO₂ (denoted as Ti/PbO₂-Tb) dimensionally stable Ti/PbO₂-Tb anode has been successfully prepared by one-step electrodeposition path for electrocatalytic degradation of imidacloprid (IMD) wastewater with high efficiency. Ti/PbO₂-Tb electrode presents higher oxygen evolution potential, lower charge transfer resistance, stronger stability, longer service lifetime and outstanding electrocatalytic activity than Ti/PbO₂ electrode. The optimum condition for IMD oxidation is obtained by analyzing the effects of some critical operating parameters including temperature, initial pH, current density and electrolyte concentration. It is proved that 70.05% of chemical oxygen demand and 76.07% of IMD are removed after 2.5 h of degradation under current density of 8 mA cm^-2, pH 9, temperature 30 °C and 7.0 g L^-1 NaCl electrolyte. In addition, the electrode displays commendable energy saving property as well as favorable reusability. The degradation mechanism of IMD is proposed by analyzing the intermediates identified by LC-MS. The present research provides a feasible strategy to degrade IMD wastewater by Ti/PbO₂-Tb electrode.

Dimensionally stable Ti/SnO2-RuO2 composite electrode based highly efficient electrocatalytic degradation of industrial gallic acid effluent

In this work, dimensionally stable Ti/SnO₂-RuO₂ electrode is successfully prepared using thermal decomposition method for the electrocatalytic degradation of high-concentration industrial gallic acid (GA) effluent in detail. The surface morphology, crystal structure and element analysis of as-prepared Ti/SnO₂-RuO₂ electrode are characterized by scanning electron microscopy, X-ray diffraction and X-ray fluorescence spectrometer, respectively. In addition, cyclic voltammetry, polarization curve and accelerated life tests are exploited to investigate the electrocatalytic activity and stability of Ti/SnO₂-RuO₂ electrode. Orthogonal experiment shows that, among the factors (current density, temperature and initial pH), current density is pivotal parameter influencing the degradation efficiency of industrial GA effluent. COD removal and degradation efficiencies of GA effluent reach up to 76.9% and 80.1% after 6 h, respectively, at the optimal conditions (current density of 10 mA cm^-2, pH 6 and 35 °C). The degradation of GA effluent follows pseudo-first-order reaction kinetics. This work provides an in-depth theoretical support and application of electrocatalytic technology to the treatment of high-concentration industrial GA effluent.

Electrochemical degradation of ciprofloxacin with a Sb-doped SnO2 electrode: performance, influencing factors and degradation pathways

Sb-doped SnO₂ electrodes were prepared with the practical sol–gel method and were used for the electrocatalytic degradation of ciprofloxacin (CIP) in aqueous solution. Results from the electrochemical characterization (including cyclic voltammetry, linear sweep voltammetry, and electrochemical impedance spectroscopy) showed that the electrode with 16 coating times (SSO-16) had the highest oxygen evolution potential of 2.2 V (vs. SCE) and the highest electrochemically active area of 3.74 cm². The results of scanning electron microscopy and X-ray diffraction showed that the coating times could affect the surface morphology and crystal structure of the electrodes, and the SSO-16 electrode had a denser surface, higher crystallinity, and smaller grain size (28.6 nm). Moreover, the experimental parameters for CIP degradation with SSO-16 were optimized, and the removal ratio of CIP reached to almost 100% within 60 min. In addition, the possible degradation pathways of CIP were proposed. And the stability and reusability of the SSO-16 electrode were also studied. These results are valuable for the preparation of high electrocatalytic performance electrodes by a sol–gel coating method for electrochemical degradation of antibiotics.

Sb-doped SnO₂ electrodes with different coating times were prepared by an optimum sol–gel method and the application on the electrocatalytic degradation of ciprofloxacin in aqueous solution were investigated.

Magnetic Assembled Anode Combining PbO2 and Sb-SnO2 Organically as An Effective and Sustainable Electrocatalyst for Wastewater Treatment with Adjustable Attribution and Construction

A new electrode consisting of a Ti/PbO₂ shell as main electrode (ME) and numerous Fe₃O₄/Sb-SnO₂ granules as auxiliary electrodes (AEs) was developed for flexible electrochemical oxidation (EO) treatment of wastewater. Material and electrochemical characterizations were carried out to study the impacts of the loading amount of the AEs on the attribution and construction of the electrode. Lignin, a complex group of polymeric macromolecules, was selected as the representative actual contaminant to test the real EO capability of the assembled electrodes with different AE loading amounts. The stability and recyclability of the electrodes were also investigated. Results showed that the roughness and the surface area of the electrode were increased with the increased loading amount of AEs, while improvement of the electrode properties was achieved only with the appropriate amounts of AEs. The optimum AE loading (such as 0.25 and 0.5 g on 6 cm² ME) boosted the EO performance of the anode toward lignin by ∼20%, making the electrode more capable in benzene ring opening. Excessive AEs were found to be unavailing, which only increased the percentage of the less accessible catalytic active sites. Moreover, a preliminary operating mechanism of this 2.5D electrode was proposed to evaluate the effect of AEs and further reveal the relationships of structure and activity of the 2.5D electrode. Finally, the electrode's lifetime was lengthened and further boosted via loading AEs and the subsequent recycling of AEs.

A comprehensive study on the electrocatalytic degradation, electrochemical behavior and degradation mechanism of malachite green using electrodeposited nanostructured β-PbO2 electrodes

This work has investigated the electrocatalytic degradation of malachite green (MG) in aqueous solution with G/β-PbO₂, SS316/β-PbO₂, Ti/β-PbO₂ and Pb/β-PbO₂ electrodes. These electrodes show high oxygen evolution over-potential and excellent electrochemical degradation efficiency for organic pollutants. The optimum conditions for the degradation of MG were obtained by studying the effects of different parameters, such as initial current densities and initial MG concentration. The remaining organic compounds concentrations (color) and chemical oxygen demand (COD) removal efficiency were investigated and compared. The results indicate that the efficiency of G/β-PbO₂ electrode for both color and COD removals is more than those of other electrodes. At the optimum conditions, the color and COD removal efficiencies of MG reached up to 100% and 94%, respectively. The observed degradation rate of MG was found to vary in the order G/β-PbO₂> SS316/β-PbO₂> Ti/β-PbO₂> Pb/β-PbO₂. Moreover, in this paper, the electrochemical behavior and adsorption characteristic of MG in aqueous solutions with different pH values were studied in details at glassy carbon electrode using both constant-current coulometry and cyclic voltammetry techniques. This study has led to the proposed mechanism for the oxidation pathway of MG and determine the absorption properties of MG in acidic, neutral and basic solutions. We also proposed the mineralization pathway of MG at β-PbO₂ electrode.