Anode Area Research Articles

Electrochemical oxidation of PFOA and PFOS in concentrated waste streams

AbstractThe electrochemical oxidation (EO) of environmentally persistent perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) with a Magnéli phase Ti4O7 electrode was investigated in this study. After 3 hours (hr) of electrolysis, 96.0 percent of PFOA (10 milligrams per liter [mg/L] in 100 milliliters [mL] 100 millimolar [mM] Na2SO4 solution) was removed following pseudo first‐order kinetics (k = 0.0226 per minute [min]) with the degradation half‐life of 30.7 min. Under the same treatment conditions, PFOS (10 mg/L in 100 mL 100 mM Na2SO4 solution) removal reached 98.9 percent with a pseudo first‐order degradation rate constant of 0.0491/min and the half‐life of 14.1 min. Although, the degradation of PFOA was slower than PFOS, when subjected to EO treatment in separate solutions, PFOA appeared to degrade faster than PFOS when both are present in the same solution, indicating possible competition between PFOA and PFOS during Ti4O7 anode‐based EO treatment with PFOA having the competitive advantage. Moreover, the EO treatment was applied to degrade highly concentrated PFOA (100.5 mg/L) and PFOS (68.6 mg/L) in ion‐exchange resin regenerant (still bottom) with high organic carbon content (15,800 mg/L). After 17‐hr electrolysis, the total removal of PFOA and PFOS was 77.2 and 96.5 percent, respectively, and the fluoride concentration increased from 0.84 mg/L to 836 mg/L. Also, the dark brown color of the original solution gradually faded during EO treatment. In another test using still bottom samples with lower total organic carbon (9,880 mg/L), the PFOA (15.5 mg/L) and PFOS (25.5 mg/L) concentrations were reduced to levels below the limits of quantification after 16‐hr treatment. In addition, the performance of EO treatment using different batch reactor setups was compared in this study, including one‐sided (one anode:one cathode) and two‐sided (one anode:two cathodes) setups. The two‐sided reactor configuration significantly enhanced the degradation efficiency, likely due to the larger anode area available for reactions.

Electroextraction of heavy metals from wastewater for the protection of natural water bodies from pollution

The most promising methods of eluates recycling are electrolysis and electrodialysis. It is possible to obtain metals and purified regeneration solutions for repeated regeneration in case of application of electrochemical methods. The processes of electrolysis of solutions of cadmium and zinc sulfates and chlorides in electrolysers of different types were explored, the influence of conditions of electrolysis on effectiveness of extraction and separation of metals, obtaining inorganic acids for repeated usage in regeneration processes was determined. Single- and double-chamber electrolysers, in which cathode was made of stainless steel and titanium anode was covered with ruthenium oxide, were used. Cathodic and anodic areas in double-chamber electrolysers were separated by the anion exchange membrane MA-41. Solution of cadmium sulfate or of zinc sulfate was found in the cathodic chamber in double-chamber electrolysers. Solution of sulfuric acid with concentration of 50 mg-equiv./dm 3 was in the anodic chamber. It is recommended to carry out electrolysis for two hours when using a single-chamber electrolyser at a voltage of 5 V with the purpose of removing cadmium from sulfuric acid solution and reusing regeneration solution of sulfuric acid. Almost complete removal of cadmium ions and concentration of sulfuric acid in anolyte is achieved in case of using a double-chamber electrolyser. However, in terms of power saving, release of cadmium should be performed in single-chamber electrolysers. However, it is recommended to perform zinc removal from eluates in double-chamber electrolysers. In this case, zinc ions are almost completely removed within four hours at voltage of 25 V. The maximum current efficiency is 42‒80 %. Conditions of separation of zinc and cadmium in the eluate are associated with acidity of the solutions. A stage-by-stage removal of metals – cadmium followed by zinc, is observed during electrolysis of the mixture of cadmium and zinc chlorides in a single-chamber electrolyser. Current efficiency of metals is 30–68 %. In the case of electrolysis of a mixture of zinc and cadmium sulfates, only cadmium (В=100 %) is removed from the solution, while zinc ions completely remain in solution. Zinc is released only at the transfer of the electrolyte to a double-chamber electrolyser

Ammonium and phosphorus recovery and electricity generation from mariculture wastewater by the seawater battery

A magnesium anode seawater battery system was built for recovering NH4-N (ammonium) and P (phosphorus) from mariculture wastewater for the first time. The Mg2+ needed for struvite formation was provided by the anode corrosion. The performances of the system were investigated by the struvite crystallization and electricity generation at different conditions. The results show that the pH value of the wastewater was rapidly increased to pH 9 and stable at about pH 10 by the seawater battery without adjusting pH. The pH range was suitable for struvite crystallization. Satisfied P recovery was achieved and it was about 99% at different conditions. The struvite formation was increased with increasing the P:N molar ratio and 1:1 was found to be suitable for enhancing the struvite crystallization. The recovery ratios of the NH4-N and P were 37.37% and 98.99%, and the residual concentrations of them were 14.09 and 0.55 mg/L, respectively. The optimum pH value was pH 9 and the NH4-N recovery was 48.07% at this pH condition. Increasing temperature could shorten the time needed for recoveries in the range from 15 °C to 35 °C. Expanding the magnesium anode area was benefit for the recovery. Increasing temperature or expanding the anode area could improve the electricity generation. The seawater battery could supply relatively stable electricity, and it was 20 mW during the process treating 0.9 L mariculture wastewater. Our results suggest that the seawater battery system is a possible approach for simultaneous NH4-N and P recovery and electricity production from wastewater.

Effects of metabolic activity of sulphate‐reducing bacteria on heterogeneous corrosion behaviors of copper in seawater

In this paper, wire beam electrode method combined with other analysis methods, that is, electrochemical impedance spectroscopy, scanning electron microscope, and X‐ray photoelectron spectroscopy, was used to investigate effects of metabolic activity of sulphate‐reducing bacteria (SRB) on heterogeneous corrosion behaviors of copper in seawater. Results show that heterogeneous corrosion behaviors of copper are associated with metabolic activity of SRB, that is, the higher metabolic activity of SRB is, the more heterogeneously current of copper distributes. In particularly, on the 5th day of exposure, SRB cells on cathodic and anodic areas display distinct micromorphologies. SRB attach onto corrosion products film surface in anodic area, while they implant in corrosion products film with self‐produced organic nanowires in cathodic area. These organic nanowires may be conductive, and help SRB to obtain electrons from cathodic area directly. The XPS results show that the relative content of corrosion products components on cathodic area is obviously different with that on anodic area when SRB with the high metabolic activity are present.

Nanotechnology in Repair and Protection of Structures State-of-the-Art

There can be many causes of deterioration in concrete structures. Concrete repaired is a specialist activity requiring fully trained and competent consultants and companies at all stages of the process. Often simple “patch and paint” strategies have been employed as short term cosmetic repairs which have failed to address the root cause of the problem and have, as a result, often failed to meet structure owners expectations. Nanotechnology provides insight into the use of nanomaterials in the following areas: Protection against ingress– moisture control– concrete restoratio – structural strengthening– physical resistance to chemicals– preserving or restoring passivity- increasing resistivity– cathodic control– cathodic protection control of anodic areas. This paper is state of the art for using nanotechnology in repair and protection of concrete structures. It is hoped that this paper will help researchers to be aware of the most recent progress in this important field.

In situ electrokinetic isolation of cadmium from paddy soil through pore water drainage: Effects of voltage gradient and soil moisture

Novel equipment based on electrokinetic geosynthetic (EKG) technology was developed for the in situ isolation of heavy metals from paddy soil through pore water drainage. Four mutually independent field plot experiments (A, B, C, and D) were conducted to investigate the effects of soil moisture (complementation or not) and the voltage gradient (0.5, 1.0, and 2.0 V cm−1) on pore water drainage capacity, cadmium (Cd) removal performance, energy consumption, and soil chemical properties. 0.03 M FeCl3 and 0.03 M CaCl2 were used to saturate the soil for 24 h, the reduction in the total soil Cd content was 29.63%, 25.93%, 38.27%, and 41.98% after 7 days of treatment, and the corresponding energy consumption was 3.48, 16.79, 12.23, and 9.47 kWh for plots A, B, C, and D, respectively. Soil moisture complementation and an increase in the electric field intensity favored soil Cd removal, but the most economical operation condition was a voltage gradient of 1 V cm−1 and no soil moisture complementation. Soil pore water drainage through gravity and Cd electromigration were the main drivers of soil Cd isolation; higher pore water drainage resulted in higher soil Cd isolation. Compared with conventional EK technology, ferric hydroxide was precipitated in the cathode area at a pH value higher than 3.0; the precipitation blocked the guiding gutter of the EKG sheet, resulting in an increased level of pore water and a higher concentration of effluent Cd concentration in the anode area. The saturation of low concentrations of FeCl3 and CaCl2 caused 18.60%–30.41% and 366%–516% increases in the soil Fe and Cl contents compared with the untreated control; however, the residual impact was acceptable for rice growth.

A novel electroosmotic chemical treatment for improving the clay strength throughout the entire region

Abstract Electroosmotic chemical treatment can be used to improve clay strength. However, this improvement is often limited to regions near the anode and/or cathode, while the areas between the electrodes remain weak. The objective of this study was to develop a suitable method to improve the clay strength throughout the entire sample. The characteristics of the test clay were studied by varying the concentration of the calcium chloride (CaCl 2 ) solution, injecting a potassium hydroxide (KOH) solution to neutralize the acidic conditions in the anode area, using a fresh sodium silicate solution in the anode compartment, and constantly injecting deionized water after injection of the sodium silicate solution. The results indicated that an increase in the concentration of the CaCl 2 solution reduced the efficiency of injecting the sodium silicate solution in the subsequent treatment stage. The use of a fresh sodium silicate solution may increase the efficiency of injecting the sodium silicate solution into clay, thereby extending the improvement range. When deionized water was injected constantly after injection of the sodium silicate solution, the Ca 2 + ions in the clay migrated toward the cathode during treatment and, simultaneously, a highly alkaline condition formed near the cathode, leading to an enhancement of the pozzolanic reaction and a significant increase in the clay strength near the cathode. Based on these results, an ECT test was conducted using a fresh sodium silicate solution and constant injection of deionized water. The results indicated that the strength of the entire clay sample was improved.

A Multiple-Ring-Modulated JTE Technique for 4H-SiC Power Device With Improved JTE-Dose Window

In this paper, a multiple-ring-modulated junction termination extension (MRM-JTE) technology for large-area silicon carbide PiN rectifier rated at 4500 V is proposed and experimentally investigated using a standard two-zone JTE (TZ-JTE) process without extra process steps or masks. Multiple modulation rings embedded inside JTE region, which is similar to varied lateral doping technology widely used in silicon devices, form a gradual decrease of effective charges in the termination region. MRM combines the advantages of two termination techniques, namely, ring-assisted JTE and space-modulated JTE, to enlarge the optimum JTE-dose window with high reverse blocking voltage in comparison with conventional TZ-JTE. A breakdown voltage of 4940 V at a leakage current of $1~\mu \text{A}$ is achieved from fabricated MRM-JTE rectifiers with a 36- $\mu \text{m}$ -thick N− epilayer doped to ${1.8} \times {10}^{{15}}$ cm−3, which is 92% of the ideal parallel-plane value. A forward current of 50 A has been measured at a forward voltage drop of 3.9 V for devices with an active anode area of 9.2 mm2, corresponding to low differential on-resistance of 1.8 $\text{m}\Omega \cdot \text {cm}^{ {2}}$ . The simulation and experimental results show that the proposed device exhibits approximately 2 times JTE dose tolerance window improvement with respect to the breakdown voltage of 4500 V.

Scale‐Up of BiVO4 Photoanode for Water Splitting in a Photoelectrochemical Cell: Issues and Challenges

AbstractThe monoclinic scheelite‐type BiVO4 is recognized as one of the promising candidate materials for a photoanode because of its 9.1 % theoretical efficiency for half‐cell solar‐to‐hydrogen conversion. Although significant research efforts have been devoted to improving the performance of the photoelectrochemical cell (PEC) of this material, they have mainly been in small anode areas with only a handful of studies on scaled‐up sizes. Herein, a facile metal–organic decomposition synthesis method was used to produce scaled‐up Mo‐doped BiVO4 photoanodes. Multiple modifications were explored and incorporated to enhance the performance of the photoanode. A large‐area (5 cm×5 cm) photoanode was successfully prepared with all modifications. The resulting photoanode gave rise to an initial photocurrent density of 2.2 mA cm−2 at 1.23 V versus reversible hydrogen electrode, under AM 1.5G illumination in a PEC, which remained at 79 % of this value after 1 h of operation. A deleterious effect of the increased anode surface area on the photocurrent density was observed, which we termed the “areal effect”. Understanding the reasons for the areal effect is indispensable for the development of large‐scale PEC devices for water splitting.

New electrodes for biofuel cells

Two new types of electrodes for biofuel elements (BFC) are proposed. One of them is based on a microchannel plate (MCP). Its peculiarity is a special structure with a large number of glass channels being 6-10 μm in diameter with an internal semiconducting surface. The MCP operation is based on the principle of the channel secondary emission multiplication of the electrons. The second type of electrode presented in the work is made of silicon carbide. This type of electrodes has a developed porous structure. The electrode pores account for at least 30% of the total volume. The pore size varies from 10 to 100 μm. Such porosity greatly increases the anode area and volume. This allows us to achieve sorption of a larger number of microorganisms interacting with the anode and transformed by electron donors. The work of the electrodes developed in BFC was tested, their effectiveness was estimated. A comparison is made with electrodes made of carbon cloth, the most widely used material for working with BFC. It is shown that the MCP based electrode is not inferior to the power characteristics of carbon cloth. The generated power when using silicon carbide was slightly lower than the other two electrodes. However, the stability of silicon carbide to aggressive media (alkalis, acids, strong oxidants, etc.), as well as to mechanical damages gives additional advantages to such electrodes compared to the materials that are commonly used in BFC. The noted features are extremely important for the BFC to work in harsh conditions of treatment facilities and to utilize wastewater components.

On the actual anode area that contributes to the current density produced by electroactive biofilms

Even with an increasing interest in scaling-up Microbial Electrochemical Technologies (MET), it is still common to focus on their “fundamentals”. An important example is the production of current density (jmax) by microbial anodes in a three-electrode arrangement (3 EA) configuration, e.g.: a graphite plate of well-defined projected (or geometric) surface area (PSA) and a cathode, both parallel to each other.With such type of anode within a 3 EA configuration, jmax‘s calculation is expected to be straightforward. Nonetheless, certain issues prevail. Occasionally, jmax is wrongly overestimated neglecting the surface of the anode that does not directly face the cathode.Here, grown biofilms of the novel electroactive bacterium Geoalkalibacter subterraneus showed that the actual area of anode that contributes to jmax is the total PSA (or apparent geometric area) immersed in the electrolyte available to form a biofilm regardless the side of the anode that faced or opposed the cathode even in a medium with low conductivity such as urban wastewater, a niche of application for METs.For the sake of normalization, researchers (and especially a “freshman” microbial electrochemist) are encouraged to: A) use the total PSA (or apparent geometric area) immersed in the electrolyte to calculate jmax or B) to cover edges and faces hidden of the anode with an electrical insulator to allow the flow of current on the side of the anode that directly faces the cathode prior calculation of jmax. This normalization can be conducted when the main goal is to quantify (and thus properly report) jmax produced when using (e.g.): a novel i) electroactive bacterium, ii) electrode material or iii) reactor design.

Corrosion Behavior of Metal Active Gas Welded Joints of a High-Strength Steel for Automotive Application

In this work, the corrosion behavior of metal active gas-welded joints of a high-strength steel with tensile yield strength of 900 MPa was investigated. The welded joints were obtained using two different heat inputs. The corrosion behavior has been studied in a 3.5 wt.% NaCl aqueous solution using electrochemical impedance spectroscopy and potentiodynamic polarization tests. Optical microscopy images, scanning electron microscopy and transmission electron microscopy with energy-dispersive x-ray revealed different microstructural features in the heat-affected zone (HAZ) and the weld metal (WM). Before and after the corrosion process, the sample was evaluated by confocal laser scanning microscopy to measure the depth difference between HAZ and WM. The results showed that the heat input did not play an important role on corrosion behavior of HSLA steel. The anodic and cathodic areas of the welded joints could be associated with depth differences. The HAZ was found to be the anodic area, while the WM was cathodic with respect to the HAZ. The corrosion behavior was related to the amount and orientation nature of carbides in the HAZ. The microstructure of the HAZ consisted of martensite and bainite, whereas acicular ferrite was observed in the weld metal.

Integrating sludge microbial fuel cell with inclined plate settling and membrane filtration for electricity generation, efficient sludge reduction and high wastewater quality

Disposal of excess sludge generated in wastewater treatment plants is complicated, energy-consuming and potentially produce secondary pollution. In this study, sludge microbial fuel cell (SMFC) was innovatively introduced into secondary settling tank to complete sludge reduction in situ. Anode of SMFC was embedded in the sediment and cathode suspended in the supernatant, besides, inclined plate anodes were installed in the middle of tank to enlarge the area of anode significantly and facilitate the utilization of biomass in the middle of settler. What’s more interesting is that, due to the inclined arrangement, anodes in the middle of reactors also stopped sludge from floating and accelerated the sludge sedimentation. The results showed that power density increased by 2.1 times, internal resistance decreased 50%, sludge reduction rate increased by 1.5 times with the installation of inclined anodes compared with normal SMFC (without inclined anodes). In addition, inclined anodes provide better conditions for the continuous operation of the reactor. Compared with static-stage, Rint of inclined plate SMFC and normal SMFC during continuous-stage were decreased by 29.77% and 35.67%, respectively. COD and SMP in supernatant decreased by 21.51% and 17.80%, respectively, and the membrane fouling of membrane module arranged in cathode was mitigated significantly.

Characterization of typical patinas simulating bronze corrosion in outdoor conditions

In order to bring the treatment of historical bronze monuments in line with proper engineering practice and cultural heritage regulations, the standardisation of artificially aged surfaces that are comparable with natural ones is still to take place. In this aim, this investigation reports a comparative study of corroded quaternary bronze samples produced by accelerated ageing tests, simulating the unsheltered and sheltered exposure conditions mainly affecting outdoor bronze monuments. The effects of run off in a dropping test (unsheltered simulation) and the exposure to stagnant acid rain in a wet & dry test (sheltered simulation) on a bronze surface were studied. A multi-analytical approach was performed including conventional analytical methods, such as a microscopy examination coupled with elemental and structural analyses of the surface. In addition, a focused ion beam (FIB) was used to produce cross-sections in the size range up to a few tens of nanometres. It is evidenced that the corrosion layers, forming a nano-porous structure, are linked to a decuprification process marked by the preferential dissolution of Cu and Zn and the formation of a SnO species network within the barrier layer. A correlation between the tin content of the alloy and the corrosion amplitude is shown: the anodic areas are related to the lowest tin-content part of the alpha phase (in the centre of the dendrite), while the eutectoid areas (including the delta phase) are cathodic and therefore not attacked. The corroded samples artificially aged are well representative of natural corrosion structures observed on outdoor bronzes.

Influence of side stripe on the corrosion of unlacquered tinplate cans for food preserves

Metal containers are used for packaging foodstuffs; more specifically, the cans used for preserving fruit have a plain body with side seam protected by a lacquer film.The traditionally used side stripe is adopted “out of abundance of caution”, as the tin present on the seam is removed by the welding process. Not using a side stripe would have practical/functional benefits for the entire production chain, with consequent reduction in the cost of the containers and in their environmental impact.Packaging of medium‐acidity products in tinplate cans is based on the principle of cathodic protection of steel by tin. To ensure that this condition persists throughout the product's shelf life, it is necessary for the anode area to be larger than the cathode area. When the seam is protected with lacquer, this condition is met. In cans where no side stripe is applied on the inner seam, the cathode area increases; this could lead to an increase in corrosion rate and consequent reduction of shelf life. However, the use of tinplate with high tin coating weight (D 11.2 g/m2) can limit this effect, under suitable packaging conditions (absence of oxygen).The aim of this study is to analyze the possibility of using cans without lacquer stripe on the electric side seam for the packaging of fruit and, more generally, of medium‐acidity products. Electrochemical measurements of model‐systems, and pack tests were used in the study.

An Inexpensive Paper-Based Aluminum-Air Battery.

Paper-based batteries are an alternative to traditional batteries due to their low cost, portability, and simplicity to operate. In the present work, we demonstrate an improved and inexpensive paper-based aluminum-air battery employing KOH as the electrolyte with sufficient energy to power small devices. The dimensions of the device, electrode size, and electrolyte concentration were optimized with respect to amperage and reproducibility. The maximum amperage of 17.4 mA and maximum power of 3.0 mW was achieved with a 9 cm2 battery with anode and cathode electrode areas of 5.1 cm2 and 3.75 cm2 respectively, using 1.5 M potassium hydroxide (KOH). In a series configuration, the batteries generate sufficient energy to power light-emitting diodes (LEDs), a flashlight, a glucometer, and a pregnancy test.

Salt‐induced iron corrosion under evaporating sessile droplets of aqueous sodium chloride solutions

The corrosion process induced by evaporation of sessile droplets from aqueous sodium chloride solutions on planar iron surfaces was quantitatively investigated. The spatial distribution of the salt inside the evaporating sessile droplet, which is influenced by the initial salt concentration in the droplet bulk, is correlated to the localization of the anodic and cathodic reactions at the electrolyte–metal interface over the footprint droplet area. At low salt concentration, the inverse of the classical well‐accepted Evans model is observed due to the hydrodynamic flows linked to evaporation: the anode area is established near the three‐phase contact line region. Increasing salt concentration leads to a more uniform pitted sessile droplet: we observed locally anodic and cathodic areas over the droplet surface at the metal–electrolyte interface, where local variations in chloride concentrations occur. In addition, the presence of corrosion products and some pits demonstrate that pitting corrosion takes place if the salt concentration reaches a threshold value, experimentally determined by an optical set‐up.

Correlation between reversion of signs of the electric field in the near-cathode plasma and anode fall potential in a short DC glow discharge

Relatively simple probe and optical experiments were performed, confirming the presence of two main scenarios for the formation of the longitudinal characteristics of a short (without positive column) glow discharge. 1. At low pressures, when there is a single point of sign reverse of the electric field at the maximum of the plasma density, the anode fall is negative and the magnitude of the anode fall is small, there is no ionization and the anode area is dark. 2. Upon an increase in pressure, two points of field reversal are to be expected, the sign of the anode fall is positive and the anode fall of potential is comparable to the gas ionization potential; therefore, the intensive ionization directly at the anode, which glows brightly, takes place.

Microstructural and Electrochemical Characterisation of Degradation in Nickel Impregnated Scandia-Stabilised Zirconia Electrode during Isothermal Annealing

The impregnation of nickel into porous ceramic scaffolds has been introduced as a promising alternative fabrication technique for solid oxide fuel cell (SOFC) anode as compared to conventional powder mixing [1]. Nevertheless, the stability of impregnated electrodes has not been extensively studied and understood [2]. SOFCs operate at a temperature range from 500 oC to 1000 oC and are expected to have a life time of 40,000 hours [3]. In this study, we examine the degradation of impregnated electrodes in a wet hydrogen atmosphere at a working temperature of SOFCs. Nickel was impregnated into a porous scandia-stabilised zirconia scaffold through 12 impregnation cycles. The impregnated electrodes contained approximately 40 wt% of nickel. Continuous van der Pauw measurement was carried out when the electrode was aged at 650 oC, 800 oC and 950 oC in an atmosphere with 5 vol% hydrogen and 95 vol% nitrogen, at open circuit. A fall in sheet conductivity was found in the electrode during ageing within 1000 min. The conductivity fall was attributed to nickel microstructural evolution during ageing. Electrochemical impedance spectra were collected at a constant time intervals during isothermal annealing at 650 oC, 800 oC and 950 oC for the impregnated electrode. Four resistance contributions were decoupled by equivalent circuit fitting, i.e. the ohmic resistance, the oxygen transfer resistance and the anodic reaction resistance, and the gas diffusion resistance. The increase in both the ohmic resistance and the polarisation resistances with time revealed the isothermal degradation brought about a diminishing active anode area. A more pronounced decrease in anodic polarisation resistance suggested a reduction in triple phase boundary (TPB) density. Secondary electron images of electrodes before and after ageing showed an increase in nickel particle size and a decrease in the number of particles, providing microstructural evidence of nickel coarsening. Nickel coarsening was identified as the main mechanism of degradation for the electrode in wet hydrogen as it caused a reduction in both TPB sites and percolating nickel paths. Combining time-dependent electrochemical performance with post-mortem electrode microstructure clarifies the physical processes behind the degradation quantified by increasing area specific resistances. [1] M. Lomberg, E. Ruiz-Trejo, G. Offer, and N. P. Brandon, “Characterization of Ni-infiltrated GDC electrodes for solid oxide cell applications,” J. Electrochem. Soc., vol. 161, no. 9, pp. F899–F905, 2014. [2] S. P. Jiang, “Nanoscale and nano-structured electrodes of solid oxide fuel cells by infiltration: Advances and challenges,” Int. J. Hydrogen Energy, vol. 37, no. 1, pp. 449–470, Jan. 2012. [3] H. Tu and U. Stimming, “Advances, aging mechanisms and lifetime in solid-oxide fuel cells,” J. Power Sources, vol. 127, no. 1–2, pp. 284–293, Mar. 2004.

A preliminary study of pilot-scale electrolytic reduction of UO 2 using a graphite anode

Abstract Finding technical issues associated with equipment scale-up is an important subject for the investigation of pyroprocessing. In this respect, electrolytic reduction of 1 kg UO 2 , a unit process of pyroprocessing, was conducted using graphite as an anode material to figure out the scale-up issues of the C anode-based system at pilot scale. The graphite anode can transfer a current that is 6–7 times higher than that of a conventional Pt anode with the same reactor, showing the superiority of the graphite anode. UO 2 pellets were turned into metallic U during the reaction. However, several problems were discovered after the experiments, such as reaction instability by reduced effective anode area (induced by the existence of Cl 2 around anode and anode consumption), relatively low metal conversion rate, and corrosion of the reactor. These issues should be overcome for the scale-up of the electrolytic reducer using the C anode.