Electrolysis Products Research Articles

Electrochemical Preparation of ZrFe2 and ZrFe1.8Ni0.2 Intermetallic Compounds by FFC Cambridge Process

The aim of the present study was to prepare ZrFe2 and ZrFe1.8Ni0.2 intermetallic compounds by FFC Cambridge process. The intermetallic compounds were prepared directly from the mixed oxide precursors, namely ZrO2-Fe2O3 and ZrO2-Fe2O3-NiO, respectively. Electrochemical de-oxidation experiments were carried out with mixed oxide pellet cathode and HD graphite anode by applying a constant cell voltage of 3.1 V in CaCl2 melt at 900 oC. The electrochemical behaviour of oxides was studied by cyclic voltammetry using metallic cavity electrodes (MCEs). The electrolysis was carried out for different durations of time to understand the mechanistic pathway of reduction of ZrO2-Fe2O3. The electro-reduced products were characterized by X-ray diffraction (XRD) technique, scanning electron microscope (SEM) and energy dispersive X-ray spectroscopy (EDS). The reduction intermediates involved Fe, CaZrO3, calcia stabilised zirconia (CSZ), Fe23Zr6, Zr6Fe3O and Zr2Fe. Single cubic C15 phase of ZrFe2 was obtained in 48 h electrolysis product. ZrFe1.8Ni0.2 was also electrochemically synthesized from its oxide precursors viz. ZrO2, Fe2O3 and NiO. Apart from ZrFe1.8Ni0.2 phase, the electro-reduced products had a Zr2Ni phase even after 72 h of electrolysis.

Separation of lanthanides erbium and ytterbium on indium electrodes by modulated potential selective extraction in molten salts and a thermodynamic and kinetic analysis of the process

The main purpose of this paper is to study the extraction and separation of key fragment elements based on the electrolytic refining process of spent fuel dry reprocessing. Firstly, the electrochemical mechanisms of Er(III) and Yb(III) in LiCl-KCl molten salts were investigated on W and In film electrodes with applied cyclic voltammetry (CV), square wave voltammetry (SWV) and open circuit potential (OCP) at 773 K. The results indicated that the reduction behaviour of In(III) and Yb(III) ions were a two-step transfer process and Er(III) ions was a one-step transfer process. Then, the kinetic parameters in electrochemical processes were calculated on an In electrode with different temperatures. The OCP approach was used to determine the equilibrium potential of Er(III)/Er(0) in the temperature range of 773 K∼848 K, and thermodynamic parameters of the In3Er alloy were provided. Based on electrochemical behaviour results, the electrochemical extraction of Er(III) and Yb(III) from LiCl-KCl-ErCl3 molten salts and LiCl-KCl-YbCl3 molten salts at liquid In electrodes was performed by constant potential and constant current electrolysis, respectively. The electrolysis products were determined by X-ray diffraction (XRD), scanning electron microscopy and energy dispersive spectrometry (SEM-EDS), the primary intermetallic compounds generated in the alloys were In3Er and In3Yb. The average extraction rates for Er(III) and Yb(III) were 94.70% and 96.54%, respectively, according to inductively coupled plasma atomic emission spectroscopy (ICP-AES) analysis. Er(III) and Yb(III) were selectively extracted and separated from LiCl-KCl-ErCl3-YbCl3 molten salts by potentiostatic control on the basis of the previously studied Lns (Er and Yb) extraction on In electrodes. The separation rate of Er(III) and Yb(III) by electrochemical selective deposition was 94.21%.

Influence of water electrolysis products on diesel engine performance in Colombia

Restrictions imposed by regulatory frameworks, the high cost of fuels, environmental impacts and the efficiency of internal combustion engines encourage research into reducing the consumption of fossil fuels. Additionally, to think about the alternative energy sources. In compression ignition engines, researchers around the world have been working for years on the use of biodiesel fuel, in order to reduce emissions and the consumption of diesel fuel. In other investigations, water electrolysis products obtained in an HHO gas generator and supplied to an internal combustion engine allow for improving performance, reducing fuel consumption and emissions. HHO gas is a mixture of hydrogen and oxygen resulting from the electrolysis process of water, with energy supplied by an electric source or accumulator. The main objective of this work is to evaluate the influence of an HHO generator products in a diesel engine that operates with diesel fuel produced in Colombia with 10 % biodiesel. The objective of this study is evaluated the influence of gas HHO on mechanical performance, fuel consumption, and polluting emissions in a single-cylinder diesel engine, performing a comparative analysis when the HHO generator operates with different amperages. The results showed a 25 % average reduction in fuel consumption between 1500 y 2500 engine revolutions when the HHO cell operated with 8 amperes. The breaking power maximum value increased a 10 %, and CO and PM10 emissions were reduced by 14 % and 53 %, respectively, at 1000 rpm. It is possible to conclude that supplying water electrolysis products in the fuel-air mixture increases the mechanical performance of a diesel engine and reduces polluting gas emissions. Additionally, research areas are opened in the development of HHO generators and standards for the application of this technology

Characterization of europium doped yttrium nano-oxide prepared by plasma electrolysis in nitrate solution under air atmosphere at room temperature

Europium-doped yttrium oxide is widely used because its unique optical properties, excellent thermal stability, and chemical stability. This paper reports a process for preparing a Y2O3:Eu3+ red fluorescent material through plasma discharge electrolysis at room temperature in a normal atmosphere and a 0.38 M Y(NO3)3 - 0.02 M Eu(NO3)3 mixed rare earth nitrate solution. Several techniques, including emission spectroscopy, X-ray diffraction, TG-DSC thermal analysis, Fourier transform infrared spectroscopy and photoelectron spectroscopy, were performed to characterize the electrolysis process and the obtained products. The results show that the electrolytic products were mainly composed of Y(OH)3, the electrolytic hydroxide products were not obviously granular, and Eu was uniformly distributed in the products. After heat treatment at 400–900 °C, cubic phase yttrium oxide was formed, and the products were irregular spherical, with particle sizes between 30 and 200 nm. After annealing at 800 °C, the products showed strong red emission at 612 nm, corresponding to 5D0→7F2 excitation. In addition, charge transfer band (CTB) absorption was observed in the excitation spectrum, and the emission spectra of fluorescent materials also showed some sharp emission bands generated by the 5D0→7FJ (J = 0,1,3,4) transition. The colour coordinate of the Y2O3:Eu3+ powder produced by plasma electrolysis is close to the standard red coordinate, showing excellent colour properties.

Study of Mass Transfer Enhancement of Electrolyte Flow Field by Rotating Cathode in Through-Mask Electrochemical Micromachining.

To solve the problem of the nonuniform distribution of temperature and electrolytic products in the electrolyte flow field during through-mask electrochemical micromachining, the use of a rotating cathode with surface structures is proposed. The rotation of the cathode increases the efficiency of heat and mass transfer by the electrolyte flow. Simulations are performed to analyze the influence of the type of surface structure, the number of surface structures, and the rotational speed of the cathode on the electrolyte flow field. The results show that the use of a rotating cathode with surface structures significantly improves the mass transfer efficiency of the electrolyte flow field in comparison with a conventional cathode structure, and, in particular, a grooved rotating cathode can increase the outlet flow velocity by about 23%. An experimental demonstration of micropit array processing shows that the use of a grooved rotating cathode increases the mass transfer efficiency by 34% and the processing efficiency by nearly 40% compared with a smooth-surfaced rotating cathode. The grooved rotating cathode also gives the highest machining accuracy. Using this cathode, a uniform micropit array with an average micropit diameter of 201.83 μm, a diameter standard deviation of 3.49 μm, and a depth standard deviation of 0.87 μm is processed.

Controllable synthesis of diazocine - investigation on electroreduction mechanism for intramolecular cyclization of 2,2′- dinitrodibenzyl in the presence of CO2

11,12-dihydrodibenzo[c,g][1,2]diazocine (Diazocine, 12), a molecular switch capable of reversible interconversion between (at least) two states by light, has been widely used in pharmacology and biochemistry. However, most of the synthetic methods so far have been limited by tedious steps, complicated derivatives, and long reaction times, resulting in poor synthetic yields of 12. Here, we propose a green, effective, and controllable strategy for synthesizing 12. The intramolecular cyclization (8-membered ring) of 2,2′-dinitrodibenzyl (1) was achieved by electrochemical reduction in the presence of CO2, and 12 and its derivatives 11,12-dihydrodibenzo[c,g][1,2]diazocine-N-oxide (DDCG-N, 11) were synthesized. The electrochemical reduction mechanism of 1 in the presence of CO2 was investigated by cyclic voltammetry (CV) and in situ FT-IR spectroelectrochemistry. The molecular structures of the electrolytic product (12) and intermediate (11) were confirmed by single-crystal X-ray diffraction, NMR, and MS. The results show that the electrochemical behavior of 1 in acetonitrile (AN) changes from a reversible two-step 1-electron transfer process (in the absence of CO2) to an irreversible 8-electron transfer process (in the presence of CO2). The 12 and 11 can be obtained by controlling the electrolytic potential and time. Under the optimum conditions, the yields of 12 and 11 were 84% and 71%, respectively.

Electrochemical Behavior of a Gold Electrode in the Aqueous Potassium Salt of Bridging 1,2,4,5-Tetraoxane

The behavior of a smooth gold electrode in aqueous solutions of the potassium salt of bridging 1,2,4,5-tetraoxane containing a biperoxide cyclic fragment was studied by cyclic voltammetry. The cathode process was analyzed in detail. It was shown that the process involves four electrons. The products of electrolysis of the potassium salt were studied, and a reaction mechanism was proposed.

ВІДНОВЛЕННЯ ШТОКІВ СИЛОВИХ ГІДРОЦИЛІНДРІВ АВТОМОБІЛІВ ЛЕКТРОЛІТИЧНИМ ХРОМУВАННЯМ

The quality of the repair of parts of military equipment and the increase of their service life largely depends on how it is organized and in what ways the restoration of malfunctioning or damaged parts is carried out. To restore the full functionality of the damaged parts, it is necessary to return them to their initial dimensions, geometric shape, hardness, corrosion resistance and other properties. One of the progressive methods of restoring the working rods of hydraulic cylinders is the application of electrolytic coatings on their working surface. The purpose of the study is to improve the method of restoration of hydraulic cylinder rods by electrolytic chroming with the aim of intensifying the process, improving operational properties and obtaining electrolytic chromium deposits of uniform thickness on the restored rods. The scientific and practical direction of the work consists in the fact that for the first time the technology of process intensification, improvement of the quality of coatings and obtaining of electrolytic chromium deposits uniform in length with the use of an ejector anode design has been considered. The research methodology is to identify the influence of the chrome plating process parameters on the uniformity, microhardness and microcracking of chrome coatings made of universal (250 г/л – СrO3; 2,5 г/л – H2SO4) та кріолітового (10 г/л – Na3AlF6; 250 г/л – СrO3; 2,5 г/л – H2SO4) of electrolytes by the ejector method. The results of the study are the establishment of the dependence of uniformity, microhardness and microcracking on the parameters of the ejector chromium plating process in standard and cryolite electrolytes and the determination of the optimal temperature and current density for use in restoring the rods of hydraulic cylinders of military equipment. The value of the conducted research is that for the first time an ejector anode is used as a positive electrode, which ensures obtaining high-quality and uniform electrolytic coatings directly in the chrome plating bath. Anode-ejector provides height-adjustable suspension suction of gaseous products of electrolysis and renewal of electrolyte in the interelectrode space due to the ejector effect in the anode tubes when the electrolyte is passed under pressure in the jet tubes. Keywords: stom density, anode-cathode distance, uniformity, cracking, microhardness, electrolyte temperature, anode-ejector.

Waste heat recovery of the hydrogen–water mixture from high‐temperature water electrolysis by cascade heat pump for steam generation

AbstractWaste heat recovery is common in high‐temperature water electrolysis production, but the latent heat from the hydrogen–water mixture is not fully utilized, and the electric heater to generate steam consumes much energy. In this research, a cascade heat pump is proposed to recover the latent heat from electrolysis products and generate steam. The heat pump can save as much as 65% electric energy compared with a single electric heater. Although in some cases, the latent heat is not enough to generate sufficient steam, it can still save 46.1% of energy. Also, this research emphasizes the significant influence of hydrogen and water proportion in electrolysis products. Compared with 80% water proportion, 50% water proportion can save 1.67 MW energy just in the water vaporization process for a 10 MW electrolyzer. The payback period is 3.43 years, which makes it worth investing.

Electrolytic Reduction of ZnO in the CaCl2-NaCl Molten Salt

Electrolytic reduction technology plays a significant role in industrial metal production. In present work, cyclic voltammetry (CV) and square wave voltammetry (SWV) were applied to study the electrochemical behaviors of ZnO cathode in the CaCl2-NaCl melt at 873 K. During the experiment, we found that the dissolution-electrodeposition mechanism (ZnO = Zn2+ + O2−, Zn2+ + 2e− = Zn) dominates the electrolytic reduction of ZnO, and the contribution of the direct-reduction from solid phase (ZnO + 2e− = Zn + O2−) is small. Furthermore, the electro-reduction of ZnO was conducted by potentiostatic electrolysis. The peak potential of ZnO to Zn was −0.48 V vs Ag/Ag+. Therefore, the metallic Zn can be obtained at an applied potential of −0.80 V (vs Ag/Ag+). When the applied potential increased to −2.00 V (vs Ag/Ag+), the Zn and CaZn3 alloy were formed simultaneously. The electrolytic products were confirmed by X-ray diffraction (XRD) analysis. This study proved the feasibility of electro-reduction technology to prepare Zn metal through the reduction of ZnO material.

Low-temperature selective synthesis of metastable α-MoC with electrochemical properties: Electrochemical co-reduction of CO2 and MoO3 in molten salts

Metastable molybdenum carbide (α-MoC), as a catalyst and an excellent support for metal catalysts, has been widely used in thermo/electro-catalytic reactions. However, the selective synthesis of α-MoC remains a great challenge. Herein, a simple one-pot synthetic strategy for the selective preparation of metastable α-MoC is proposed by electrochemical co-reduction of CO2 and MoO3 in a low-temperature eutectic molten carbonate. The synthesized α-MoC shows a reed flower-like morphology. By controlling the electrolysis time and monitoring the phase and morphology of the obtained products, the growth process of α-MoC is revealed, where the carbon matrix is deposited first followed by the growth of α-MoC from the carbon matrix. Moreover, by analyzing the composition of the electrolytic products, the formation mechanism for α-MoC is proposed. In addition, through this one-pot synthetic strategy, S-doped α-MoC is successfully synthesized. Density functional theory (DFT) calculations reveal that S doping enhanced the HER performance of α-MoC by facilitating water absorption and dissociation and weakening the bond energy of Mo-H to accelerate H desorption. The present work not only highlights the valuable utilization of CO2 but also offers a new perspective on the design and controllable synthesis of metal carbides and their derivatives.

Experimental study on electrochemical machining of TC11 titanium alloy blades based on cylindrical array microstructure cathodes

Titanium alloys have a wide range of applications in aerospace, however, this material is very sensitive to changes in the flow field during electrochemical machining (ECM) and suffers from frequent short-circuiting and poor surface quality. Studies have shown that optimization and improvement of the cathode structure often improve the processing properties of the material. To process titanium alloy under a steady state, the laser processing system was used to prepare cylindrical array microstructure on the end surface of cathode. The comparison between the original and improved cathode was conducted in ECM experiments. The experimental results showed that serious flow marks existed on the original cathode processing surface. Within the range of processable voltage, short circuits occurred at the processing heights of 1.823 mm and 1.655 mm. The improved cathode can process a bright finish surface without flow marks and there were no short circuits. The influence of two microstructure arrangements on the blade surface quality was also investigated. Compared to inline cylindrical array (ICA) cathode. The processing gap equilibrium flow rate of the staggered cylindrical array (SCA) cathode is about 0.3 L/min higher. The average surface roughness of the blade hub was reduced from 1.632 µm to 0.574 µm. Additionally, there are multiple layers of electrolysis products adhering to the non-machined surface and the machined sidewall of the blade. The oxygen content of the outer layer is higher than that of the inner layer, and the oxygen content of the non-machined surface is significantly higher than that of the machined sidewall. The microstructure cathode designed in this paper realizes the stable processing of titanium alloy in passivation electrolyte.

A gravity-independent single-phase electrode reservoir for capillary electrophoresis applications.

Capillary electrophoresis (CE) holds great promise as an in situ analytical technique for a variety of applications. However, typical instrumentation operates with open reservoirs (e.g., vials) to accommodate reagents and samples, which is problematic for automated instruments designed for space or underwater applications that may be operated in various orientations. Microgravity conditions add an additional challenge due to the unpredictable position of the headspace (air layer above the liquid) in any two-phase reservoir. One potential solution for these applications is to use a headspace-free, flow-through reservoir design that is sealed and connected to the necessary reagents and samples. Here we demonstrate a flow-through HV reservoir for capillary electrophoresis that is compatible with automated in situ exploration needs, and which can be electrically isolated from its source fluidics (in order to prevent unwanted leakage current). We also demonstrate how the overall system can be rationally designed based on the operational parameters for CE to prevent electrolysis products produced at the electrode from entering the capillary and interfering with the CE separation. A reservoir was demonstrated with a 19 mm long, 1.8 mm inner diameter channel connecting the separation capillary and the HV electrode. Tests of these reservoirs integrated into a CE system show reproducible CE system operation with a variety of background electrolytes at voltages up to 25 kV. Rotation of the reservoirs, and the system, showed that their performance was independent of the direction of the gravity vector. This article is protected by copyright. All rights reserved.

Electrochemical behaviour of anthraquinone dyes in non-aqueous solvent solution. Part II. Controlled potential electrolysis of alizarin

This article is the second part of our already published research results (Caram, Banera, Martínez Suárez, Mirífico, 2017). The present work aims to characterise/identify reaction intermediates and final products of the cathodic electrolysis of alizarin (AH2) in solution of DMF and ACN with TBAP and NaClO4 as supporting electrolytes to corroborate the reaction mechanism previously published by us. Intermediates and reaction products are accumulated by controlled potential electrolysis (CPE) of AH2 performed at the potentials of the first, second, and third charge transfers. Progress of the electrolysis is followed by CV. The techniques employed for the characterisation/identification of the involved chemical species are CV, UV–Vis, FTIR, 1H and 13C NMR, ESR, elemental analysis, and quantum chemical computations based on density functional theory (DFT). Some aspects of the mechanism are corroborated, some details are modified, and new insights are obtained. Intermediates are detected by CV, and the structure of some of them (AH2● ─, AH3●, and AH─) is confirmed by ESR and by the identity of the isolated reaction products (1-hydroxy-2-methoxyanthracene-9,10-dione (AH-CH3) by adding an excess of CH3I at the end of the CPE in DMF/TBAP and NaClO4 as the electrolyte systems, and sodium 1-hydroxy-9,10-dioxo-9,10-dihydroanthracene-2-olate (AH-Na) in ACN/NaClO4). Ion pair formation between AH2● ─ semiquinone radical anion with Na+ is significant. The homogeneous dissociation equilibrium AH3─ ⇄AH22– + H+ does not occur, and AH2• – + AH2 ⇄ AH – + AH3• is a slow process more shifted to the right in DMF/TBAP electrolyte medium. AH-CH3 and AH-Na are clear evidence of the self-protonation reaction of AH2• –. Ca. 20 % of the initial moles of AH2 are converted into AH-CH3 in DMF/TBAP and NaClO4 as the electrolyte systems. CPE of AH2 in ACN/NaClO4 results in reaction products that are insoluble and are coating the electrode, ca. 80 % of the initial moles of AH2 are recuperated as pure AH-Na. AH-CH3 and AH-Na contain the carbonyl-quinone groups in their structures. The applied potential does not modify these results. AH-CH3 and AH-Na are electrochemically (CV) characterised. The acidity of the quinone dye, the homogeneous protonation/deprotonation equilibriums, the intramolecular hydrogen bonding, and the easy air oxidation and protonation of some of the intermediates have led to the obtained results.

Study on electrochemical reduction mechanism of p-nitrophenylacetic acid prepared by electrocarboxylation

The direct carboxylation of organic halides under CO2 atmosphere by electrochemical reduction is an effective way to realize the value utilization of waste (CO2), and has great potential in green organic synthesis. P-nitrophenylacetic acid is a chemical raw material in great demand, which can be used not only in medicine and other organic synthesis intermediates but also in biochemical research. In this paper, the electrochemical reduction mechanism of p-nitrobenzyl bromide (PNBB) in N2 and CO2 atmosphere was investigated by cyclic voltammetry (CV), in-situ FT-IR spectroelectrochemistry, and bulk electrolysis experiments. Under N2 conditions, the electrochemical behavior of PNBB in aprotic acetonitrile solvent is a 1-electron irreversible transfer process. However, in the presence of CO2, it is a completely irreversible 2-electron transfer process. The electrolytic products were analyzed by 1H NMR, 13C NMR and MS. The results showed that the electrolytic products were 1,2-bis(4-nitrophenyl) ethane and p-nitrophenylacetic acid under N2 and CO2 conditions, respectively. The successful preparation of p-nitrophenylacetic acid provides more possibilities for the “green” synthesis of helpful chemical products from organic halides.

Electrolytic reduction of Gd2O3-ZnO in NaCl-CaCl2 Molten Salt

The electrochemical behaviors of Gd2O3, ZnO and Gd2O3-ZnO in NaCl-CaCl2 molten salt was studied by cyclic voltammetry and square wave voltammetry, and the corresponding constant potential electrolysis and XRD analysis indicated that the reduction processes were in agreement with the process that 3PI (metal∣oxide∣electrolyte three-phase interline) expanded with time from surface to interior of the cathode. Moreover, the addition of ZnO could promote the electrochemical reduction of Gd2O3. According to the electrochemical behavior (CV) and the characterization (XRD and SEM-EDS) of electrolytic product, the intermetallic compounds, GdZn12, Gd2Zn17 and Gd13Zn58, were generated during the electrolysis of Gd2O3-ZnO cathode without dendritic deposits.

A new voltammetric approach for the determination of the growth retardant paclobutrazol in the presence of difenoconazole in pesticide preparations

Paclobutrazol (PBZ) belongs to the group of triazole pesticides, which act as inhibitors of the synthesis of phytohormones and thereby regulate plant growth. In this study, the electrochemical oxidation of this pesticide was investigated for the first time. PBZ provides on a boron-doped diamond electrode (BDDE) one irreversible anodic peak over a wide pH range of the supporting electrolyte at a significantly positive potential of ca. +1950 mV (vs Ag/AgCl), which is suitable for electroanalytical purposes. Based on the LC-MS analysis of the products of electrolysis, the mechanism of the electrochemical oxidation of PBZ was also proposed. The method developed for the determination of PBZ using differential pulse voltammetry in connection with BDDE in the supporting electrolyte of 0.07 mol L−1 NaOH with 33 % of acetonitrile provided a very low limit of quantification amounted to 2.6 × 10−7 mol L−1. Under optimized conditions, the determination of the studied plant growth regulator is also possible in the presence of the other insecticide difenoconazole, which is usually found in commercial preparations mixed with PBZ. For natural water samples with very low concentrations of pesticides, a method of analyte pre-concentration using strong acid Amberlite® IRC120 H catex was developed. The proposed procedures were successfully applied for the analysis of model solutions, commercially available pesticide preparations, and spiked natural waters.

Increasing RES penetration through H2 technologies on Flores island, Azores: A techno-economic analysis

On Flores island (Azores, Portugal), energy production depends up to 47% on fossil fuels, namely Diesel. To minimize CO2 emissions, the dependency on fuel prices, and to mitigate the consequences of variability and intermittency of renewable energy sources, a new energy system, based on H2 storage was analysed. To achieve the optimal size of the system, a computer model was developed and a multi-objective genetic algorithm function was used to minimize three objectives: the difference of levelised cost of energy (△LCOE), CO2 emissions and the percentage of renewable energy dumped (RRES, dump). From the set of solutions obtained, one that meets RRES, dump ≤ 1%, lowest CO2 emissions and lowest △LCOE is chosen and an economical and energetic analysis is performed. The newly proposed system reduces Diesel consumption by 68,7% (1057487 L/year) and CO2 emissions by 65,9% (2455,1 CO2 tons/year) achieving a renewable energy sources (RES) penetration of 89% (36% increase), but fails to decrease the levelised cost of energy (56,62 €/MWh increase). However, a way to make the project viable through financial support is presented and an alternative to reduce the levelised cost of energy by commercialising the products of electrolysis, hydrogen and oxygen, is proposed. Finally, it is expected that with further research and development of H2 technologies, economic and energetic results will get more advantageous, opening up new perspectives for the future.

Accelerated Separation of Uranium from Lanthanides (La, Ce, Sm) in LiCl-KCl Eutectic by Porous Aluminum Electrodes

In order to optimize the application of Al electrodes in pyrochemical reprocessing of spent nuclear fuel, the feasibility of porous Al electrodes to separate actinides-lanthanides (An-Ln) in LiCl-KCl eutectic melt was explored. The separation efficiencies and rates of U and lanthanides (La, Ce, Sm) on Al electrodes with regular and irregular and without pores were compared. U was selectively recovered in the form of U-Al alloys by controlling the potential (−1.2 V) on both Al rod and porous Al electrodes. X-ray diffraction (XRD) and scanning electron microscopy (SEM)-energy dispersive spectroscopy (EDS) showed that the obtained granular alloys were mainly Al3U and Al4U, and inductive coupled plasma optical emission spectrometry (ICP-OES) indicated that there was almost no Ln in the electrolysis products. Positively, the required separation time was greatly shortened, and the separation rate was effectively improved when porous Al electrodes were used. In addition, the Al honeycomb electrode with regular pores has better kinetic performance compared with Al foam electrodes with irregular pores. The results indicate that the specially designed porous Al electrodes may have a good application prospect for the separation of An-Ln in the pyrochemical reprocessing of spent nuclear fuel.

Greenhouse gas reduction and economic cost of technologies using green hydrogen in the steel industry

Reducing greenhouse gas (GHG) emissions from the steel industry is one of the top priorities for mitigating climate change. Although hydrogen has been considered as a key element to accomplish this task, the effects of various hydrogen-using technologies in steel mills have not been analysed and compared to each other. This paper quantitatively analysed the greenhouse gas reduction in steel mills by the use of hydrogen produced from electrolysis with renewable electricity. The four following methods of using green hydrogen were proposed and analysed: 1) use of hydrogen directly in the hydrogen steelmaking process, 2) use of hydrogen to convert byproduct gases produced from steel mills into methanol, 3) use hydrogen to convert the byproduct gases into methane, and 4) sell hydrogen to the hydrogen station and use of oxygen, another product of electrolysis, to reduce the use of air separating unit in steel mills. Not only the greenhouse gas reduction benefits but also the economic cost of these four methods were evaluated. As those results can vary according to country, the economic cost and GHG reduction benefits were determined for the representative steel-producing countries of China, India, Japan, the United States, Russia, South Korea, and Germany. The economic cost was evaluated not only for the present (2020) but also for the future (∼2040) because these methods are more likely to be implemented in the future. Currently, in the representative steel-producing countries, Method 1 was analysed to have the largest GHG reduction among the four methods; but it also showed the largest cost because of its large capital expenditures and electricity cost. Method 2, which converts the byproduct gases into methanol, was shown to offer larger GHG reduction and smaller economic cost than Method 3, which converts the byproduct gases into methane. Comparing Methods 1 and 2, Method 2 offered smaller GHG reduction but a much smaller economic cost than Method 1. Although the cost of Method 4 is currently the smallest, the economic cost of Method 2 is predicted to become lower than that of Method 4 in the future, near 2030, because the future prices of hydrogen and the CO2 allowance are expected to decrease and increase, respectively. These results can be utilized when steelmaking country or steelmaking company make their decision on how to decrease the GHG emissions by using green hydrogen.