Electrochemical Generation Of Ozone Research Articles

Simultaneous ozone and hydrogen peroxide electrosynthesis via defect modulation in Ni, Sb‐doped SnO2 electrocatalysts

AbstractElectrochemical synthesis of green oxidants O3 and H2O2 is valuable for applications, but challenges persist in enhancing the O3 and H2O2 generation activity and combined application. Herein, we modulate the surface Ni active sites and oxygen vacancy defects content in Ni‐Sb‐SnO2 electrocatalysts to enhance selectivity for electrochemical ozone generation (EOP) and two‐electron electrochemical oxygen reduction reactions (2e− ORR). The Ni active sites and oxygen vacancy defects enriched electrocatalysts resulting in an ozone faradaic efficiency of 48.1%, while non‐enriched electrocatalyst obtained 90% selectivity for H2O2. Theoretical calculations revealed that Ni‐Sb‐SnO2 efficiently captures O2 with defective Ovac2 stabilize intermediates, facilitating O3 and H2O2 synthesis. Moreover, concerted EOP and 2e− ORR enable concurrent generation of O3 and H2O2 for efficient synergistic degradation of organic pollutants, while attenuating the energy demands of the electrolyzer. This study provides an appealing strategy for simultaneous production of O3 and H2O2 with applications in wastewater treatment.

Electrochemical generation of ozone for application in environmental remediation

This work focuses on the production, in continuous mode, of ozone using a new electrochemical cell, specially designed and manufactured with 3-D printing to produce in a very efficient way high concentrations of this powerful oxidant. The gaseous ozone produced is tested in the degradation of a synthetic waste containing methomyl. The new cell has been characterized in terms of flow distribution, mass transfer, and production of ozone, being able to reach efficiencies as high as 9.5 g/kWh, which may be even competitive with those produced with the corona discharge technology. The prototype manufactured with an electrode area of 1.5 cm2 can produce a stream containing 30 mg/h of O3. This stream can be used to degrade methomyl. However, the direct bubbling was not found to be very efficient and activation of ozone with the simultaneous irradiation of UV light or the dosing of hydrogen peroxide was needed to improve performance, showing important synergism. The efficient removal of methomyl from wastewater opens the window for the development of alternative technologies to direct anodic oxidation based on the production and dosing of gaseous oxidants such as ozone. The operation of these new technologies does not depend on the salts contained in wastewater and prevents the deterioration in the quality of the waste because it does not leave any residue after application in the treated waste.

ELECTROCHEMICAL OZONE GENERATION FOR PALM OIL MILL WASTEWATER TREATMENT USING NICKEL/ANTIMONY DOPED TIN OXIDE ANODES

Ozonation have been employed in organic matter degradation and discoloration process of wastewater. In this study, nickel-antimony doped tin oxide (NATO) anode was employed to generate ozone for palm oil mill effluent (POME) wastewater treatment. NATO was synthesized varying Ni concentrations and calcination temperatures. The materials were characterized by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDX) and X-ray Photoelectron Spectroscopy (XPS) techniques. All materials showed rutile structure. The electrode displayed a smooth cracked mud surface morphology. Regarding the oxidation state, the binding energies of the Sb 3d3/2 peak were observed at 540.62 eV and 541.51 eV corresponding to Sb3+ and Sb5+, respectively. The key findings show that increasing calcination temperature increases ozone current efficiency obtained from the absorbances of dissolved ozone in liquid phase and current density, which decreases with increasing Ni content. The highest current efficiency and current density (i.e. ca. 30% and 0.18 Acm-2 in 1 M H2SO4 at 2.7V) was achieved at 2%mole ratio Ni content calcined at 650°C. Regarding POME treatment, discoloration and degradation efficiency increased with electrolysis time from the initial chemical oxygen demand (COD) and total organic carbon (TOC) of 1,780 and 96 mgL-1, respectively under the aforementioned conditions. The highest removal efficiency of 80% was achieved within 10 min discoloration and 15 min for TOC and COD. The electrochemical ozone generation using NATO anode have shown high efficiency in the POME treatment due to •OH radicals and O3. NATO is a promising electrocatalyst candidate for wastewater treatment.

A long-term-stable continuous flow electrochemical ozone generator with high current efficiency

An ozone generator with long-term stable operation, high ozone output, and low production energy was investigated based on a high-performance PbO2 gas diffusion electrode.

Phase/Size‐Controlled Synthesis of Nanostructured PbO2Microspheres for Efficient Electrochemical Ozone Generation

AbstractTraditional electrochemically prepared lead dioxide (e‐PbO2) is one of the most used electrode materials for electrochemical ozone production (EOP), because of its high catalytic activity, excellent electrical conductivity, relative stability and low cost. But the electrochemically prepared conditions are complicated and harsh. Bulk PbO2electrodes have the very limited surface area and are inconvenient to process into the fine film electrodes for a PEM electrolyser. In contrast, chemical synthesis is easy to prepare uniform PbO2catalysts with high surface area and catalytic activity. Here, a facile one‐pot approach to prepare a highly active PbO2microsphere catalyst was established and used for the EOP reaction in a PEM ozone generator. Sodium hydroxide could be used to regulate the relative content of α/β allotropic phase and crystallite size of PbO2microspheres. Experiment results revealed that high β phase content and large β‐PbO2crystallite size were beneficial to the high EOP activity. By optimizing the composition and crystal structure, chemically prepared PbO2could have much better EOP performance than e‐PbO2.

Unraveling the Role of F in Electrochemical Ozone Generation on the F-Doped PbO2 Electrode

Unraveling the Role of F in Electrochemical Ozone Generation on the F-Doped PbO₂ Electrode

Effect of Nickel Concentration on Ozone Production using Nickel-Antimony Doped Tin Oxide for Wastewater Treatment

Nickel-antimony doped tin oxide (NATO) catalyst has greatly considered its capability to treat high organic matter and eliminate colour in wastewater as palm oil mill wastewater with electrochemical ozone generation. This study presents the optimal Ni content of NATO and its properties to enhance ozone generation. The NATO anodes were fabricated by dip-coating, varying the Ni content between 0.5% and 5%. The key findings show that all anodes showed a single phase of rutile structure with the cracked mud on the surface. The binding energies of the Sb3d3/2 peak at 540.48 eV and 541.58 eV agree with Sb3+ and Sb5+, respectively. The optimal ozone current efficiency of 37% at the current density of ca. 0.22 A cm-2 in 0.5 M H2SO4 at 2.7V was obtained on the NATO anode with 2% Ni content calcined at 700 oC. The palm oil mill wastewater treatment result showed that decolourisation TOC and COD removal efficiency increased with increasing electrolysis time. The colour removal efficiency achieved was more than 85% for a reaction time of 15 min. The efficiency of TOC and COD removal was reached ca. 80% in 20 min. The overall results appeared that NATO with electrochemical ozone generation could be employed to treat palm oil mill wastewater with high efficiency due to •OH and O3.

Tuning electrochemical water oxidation towards ozone evolution with heterojunction anode architectures

Heterojunction architectures on Ni–Sb–SnO2 (NSS) electrocatalysts tuned electrochemical ozone generation efficiency, described by the potential of zero charge in Sabatier's volcano trends with NSS/SiOx at the apex.

Facile Synthesis of β-PbO2 Nanoparticles Range from 10–30 nm and their Application for Ozone Generation

β-PbO2 is an important high oxygen overpotential anode coating material. Further study on nanoscale β-PbO2 with higher performance and lower cost is a critical issue in order to develop the electrochemical ozone generator. Herein, an improved β-PbO2 nanoparticles synthesizing strategy based on the traditional Pb(OAc)4 hydrolysis method is proposed in this work, which is more scalable for industrial-scale production compared with existed nano β-PbO2 synthesizing methods. The possible mechanism of synthesizing β-PbO2 nanoparticles via Pb(OAc)4 hydrolysis was discussed for the first time. Based on the proposed mechanism, the size and morphology of the β-PbO2 nanoparticles were effectively controlled, and alternative raw material that can significantly reduce costs was developed. SEM, TEM, XRD, and XPS results indicate that pure phase β-PbO2 nanoparticles range from 10–30 nm were obtained. In addition, the use of alternative raw materials reduces the cost by 90%–95% compared to the traditional Pb(OAc)4 hydrolysis method. The β-PbO2 nanoparticles showed good ozone generation performances. The energy consumption per unit ozone of the β-PbO2 nanoparticles is reduced by 51.9% at the optimized operation condition than the reference PbO2 particles used for comparison.

A highly stable microporous boron-doped diamond electrode etched by oxygen plasma for enhanced electrochemical ozone generation

The boron-doped diamond (BDD) electrode, having ultra-high oxygen evolution potential and anodic stability, is potentially considered the ideal candidate for the next-generation ozone generator despite the relatively low current efficiency. In this work, we first report using a microporous BDD electrode etched by oxygen plasma, denoted as p-BDD, to improve the performance of electrochemical ozone generation. Two parameters, including O2 plasma etching temperature and time, are experimentally optimized. We demonstrated that the electrochemically active surface area (ECSA) of the optimal p-BDD is 2.51 times that of the bare BDD, and this p-BDD shows about one-quarter lower charge transfer resistance than the latter. Under the same unit energy consumption, the p-BDD has 3.76 times the ozone generation capacity compared to the latter. The p-BDD shows excellent long-term stability, only having 4.2% of the decrease in the current density up to 40 h of consecutive water electrolysis under the steady-state period, and it also remains a 100% recovery rate in its capability of electrochemical performance after mild treatment by cycling at a diluted sulfuric acid solution for 200 s

Fabrication of several SnO2-based anodes for electrochemical ozone generation: comparison, characterization and application

Fabrication of several SnO2-based anodes for electrochemical ozone generation: comparison, characterization and application

Disinfection of urines using an electro-ozonizer

In this work, the disinfection of urines polluted with Klebsiella pneumoniae (K. pneumoniae) using a commercial electro-ozonizer is described. The device consists of a membrane-electrode assembly flow cell that specially promotes the electrochemical generation of ozone. Results show that a complete disinfection is attained in less than 180 min when working at current intensities higher than 0.5 A. The higher the current intensity, the higher the disinfection rate. Furthermore, the use of an electro-ozonizer for treating diluted urines leads to higher disinfection efficiencies. Ozone and chlorine-based disinfectants (hypochlorite and chloramines) were identified as the main oxidant species involved in killing bacteria. The combined effect of all disinfectants promotes higher removal efficiencies in comparison with the single effect of ozone evaluated in a urine matrix without chlorides, being more remarkable at lower current intensities. The crystal violet assay showed that cell wall is damaged by the electrogenerated oxidants and it is more remarkable by the combined effect of ozone and chlorine disinfectants when increasing the current intensity. Finally, the degradation of total proteins and genetic material (DNA) were also monitored and related to the oxidants produced during the electrochemical process.

Electrolytic Ozone Generation at Pt/Ti Electrode Prepared by Multiple Electrostrike Method

Electrochemical ozone generation at an easily prepared platinum-modified titanium electrode was investigated and compared with that at boron-doped diamond (BDD) and Pt electrodes. The Pt/Ti electro...

INVESTIGATION OF ELECTROCHEMICAL COLOR REMOVAL FROM ORGANIZED INDUSTRIAL DISTRICT (OID) WASTEWATER TREATMENT PLANTS USING NEW GENERATION Sn/Sb/Ni-Ti ANODES

<p>In this study, the application of Sn/Sb/Ni-Ti electrodes for the treatment of waste streams were investigated which is promising for ozone production by electrolysis of water because of their stability and high potential for ozone evolution reaction. These series of anodes have a high electrochemical ozone generation potential at ambient conditions (approximately up to 40% current efficiency). But using and testing of these novel anodes for real wastewater are too limited in the literature. Titanium mesh substrate coated with Sn/Sb/Ni-Ti alloy was used as anode immersed in wastewater at room temperature with platinized titanium cathode. These electrodes used for COD and color removal from OID wastewater in Inegol, Bursa, Turkey. Five operational parameters were evaluated for electrochemical COD and color removal processes, such as pH, salt content, applied voltage/current, current efficiency and contact time. Experimental results showed that after 30 min the electrochemical oxidation efficiency of COD and color could reach up to 98% and 99% respectively at pH 8.2 and temperature of 25°C as the optimum conditions. Current density observed as the most effective parameter for COD and color removal efficiencies. The lowest energy consumption was between 10-25 mA cm-2 of current density with only 0.6 kWh gCOD−1, while the highest energy consumption was 100 mA cm-2 of current density with 9.12 kWh gCOD−1 . The optimum current density value has been found as 50 mA cm-2 with 4.05 kWh gCOD−1 . These results were also supported with ANOVA test.</p>

Compact portable indicator-meter of ozone concentration

Compact portable indicator-meter of ozone concentration is the most suitable device to measure the ozone concentration in the work zone and control its maximum allowable concentration. The analysis of existing ozone measurement methods showed that the amperometric method is the most suitable for designing such indicators-meters. Accordingly, two-electrode electrochemical ozone sensors of the amperometric type based on solid and liquid electrolyte are selected as the primary measuring detectors. Studies of possible schemes for constructing input circuits of the indicator-meter showed that it is advisable to connect an ozone sensor with a solid electrolyte directly to the input of an operational amplifier functioning in a current-voltage converter mode without a load resistor. The ozone sensor with a liquid electrolyte is better to connect to a load resistor of 100 Ohms, the signal from which is fed further to the input of an operational amplifier functioning in a voltage converter mode. The structural and schematic diagrams of the ozone concentration indicator are developed and an experimental sample is made. It is calibrated at 4 mg/m3 point using an electrochemical ozone generator. The ozone concentration produced by an electrochemical generator is tested using the iodometric method and the error does not exceed 5 %. The experimental study of the errors of the indicator-meter of ozone concentration with a sensor based on solid electrolyte was conducted in the main measurement range, taking into account its higher sensitivity and lower error of nonlinearity, compared with the sensor based on liquid electrolyte. The experimental study of the errors of the ozone concentration indicator-meter with a sensor based on a liquid electrolyte is conducted in an extended measurement range. For the tests, two series of studies are conducted with an interval of 1,5 months, which made it possible to establish changes in the sensor characteristics. The study results of two variants of an experimental sample of the ozone concentration indicator-meter with solid and liquid electrolyte sensors showed that the relative measurement error does not exceed 25 % in the ozone concentration range of 0,1-10 mg/m3. And in the range of 0,05-0,5 mg/m3 the error value from full scale does not exceed 22 %. These values correspond to the existing standards.

Anode with the Active Layer for Electrosynthesizing Ozone in a System with Solid Polymer Electrolyte

The synthesis of catalytic coatings on porous titanium electrodes by the method of magnetron sputtering is considered. The content of dopant ions Fe3+ and F– is optimized as regards the activity and stability of the PbO2 catalyst in the reaction of ozone electrogeneration as well as the current efficiency with respect to ozone. It is shown that the best characteristics of the electrochemical ozone generator are observed on the PbO2 catalyst doped with Fe3+ and F– ions in the amount of 3–4 and 1–2 at %, respectively.

Fabrication of Spin-Coated Ti/TiHx/Ni-Sb-SnO2 Electrode: Stability and Electrocatalytic Activity

A novel three-layer anode having the composition Ti/TiHx/Ni-Sb-SnO2 (Ti/TiHx/NATO) was successfully prepared by a spin-coating and pyrolysis process aiming at a long service lifetime and good electrocatalytic properties for ozone formation. The TiHx as an interlayer was produced by electrochemical cathodic reduction of a coated layer of the TiOx on the titanium substrate. Spin coating and thermal decomposition were used to deposit the Sn-Sb-Ni precursor on the surface of the prepared Ti/TiHx electrode. Cyclic and linear scanning voltammetry, Raman spectroscopy, scanning electron microscopy (SEM) and X-ray diffraction (XRD) were used to reveal the electrode performance and morphology. Results show that the onset potential for the oxygen evolution reaction (OER) of Ti/TiHx/NATO is higher than for Ti/NATO. They also indicate that the service lifetime of the Ti/TiHx/NATO is twice as long as the Ti/NATO at a current density of 50 mA.cm−2 at room temperature. Electrochemical ozone generation and degradation of the methylene blue were investigated to confirm selectivity and activity of the electrodes. After 5 min electrolysis, a current efficiency for ozone generation of 56% was obtained the electrode with TiHx while 38% was obtained on Ti/NATO under same conditions. The results also confirm that the Ti/TiHx/NATO has a higher kinetic rate constant and decolorization efficiency for removal of the methylene blue compare to the Ti/NATO. The rate constant for the pseudo-first ordered reaction of methylene blue degradation showed high values of 350 × 10−3 min−1 for Ti/NATO and 440 × 10−3 min−1 for Ti/TiHx/NATO.

Effective degradation of carbamazepine using a novel electro-peroxone process involving simultaneous electrochemical generation of ozone and hydrogen peroxide

An advanced electrochemical oxidation process (electro-peroxone) involving a dual electrode system was developed to degrade recalcitrant carbamazepine (CBZ). During this electro-peroxone (E-peroxone) process, ozone was electrochemically produced by anodic oxidation of water in a membrane electrode assembly (MEA) cell and H2O2 was simultaneously generated by the sparged O2 using a carbon-polytetrafluorethylene (C-PTFE) cathode. The O3 and H2O2 electrogenerated in situ synergistically produce hydroxyl radicals (OH), which are much more easily oxidized than O3. As a result, the removal efficiencies of CBZ and its TOC reached 99.8% and 97.6% after 15min and 90min of E-peroxone treatment, respectively, these figures remaining stable after multiple tests. The E-peroxone process is therefore a promising and effective method for degrading ozone-refractory organic contaminants in wastewater.

Electrochemical generation of ozone in a system with a solid polymer electrolyte

Mechanisms of ozone generation in an electrochemical system with a solid polymer electrolyte and the electrode and catalytic materials used in systems of this kind are considered. The influence exerted by the process parameters and by the type of electrolyte and electrocatalysts on the productivity of the system and on the current efficiency by ozone is analyzed.

Electrochemical Generation of Ozone: Comparison of IrO2 series with Pt/SnO2 anode support in solid membrane cell

Electrochemical Generation of Ozone: Comparison of IrO2 series with Pt/SnO2 anode support in solid membrane cell