Nitrate Electrolyte Research Articles

Effect of Aqueous Electrolyte Composition on Efficiency of Electrochemical Post-Processing of Additive Manufacturing Products from Ti-6Al-4V Alloy Obtained by Selective Electron Beam Melting

The influence of the anionic composition of an aqueous electrolyte on the efficiency of the electrochemical leveling of the initial microgeometry of samples obtained by the selective electron beam melting (SEBM) at the following mode parameters was studied: current density – 20 A/cm2, initial interelectrode gap – 0.3 mm, average speed of electrolyte pumping – 12 m/c. Aqueous solutions of sodium chloride, nitrate, perchlorate and bisalt electrolytes based on them were studied. It was that aqueous solutions of sodium perchlorate have the best microleveling properties among the studied working media, which provides the ability to reduce the parameters Ra and Rz from values of 35 and 180 μm, respectively, to values of 3.2 and 20 μm during electrolysis of 30 s in a direct-flow electrolyzer. It was established that the microgeometry leveling corresponds to the model of the secondary distribution of dissolution rates; two main factors were identified that significantly influenced on the result: polarization of the electrodes and a decrease in the oxidation state of metal ions passing into the solution during electrochemical machining in the vicinity of the depression in relation to the protrusion due to changes in the local conditions of electrolysis. Microetching along grain boundaries in the studied electrolytes was not detected at the accepted parameters of the electrolysis mode.

The influence of Sodium Nitrate electrolyte on Aluminium scrapped wheel in the ECM process

The influence of Sodium Nitrate electrolyte on Aluminium scrapped wheel in the ECM process

Reaction Mechanisms of High-Rate Copper Electrochemical Machining in Nitrate Electrolytes.

The high-rate electrochemical dissolution of copper in nitrate electrolytes is investigated primarily via polarization curves, while varying parameters such as the electrolyte flow velocity, the electrolyte resistance, the anode geometry, and the temperature. This study focuses on the re-rise in current at high voltages after the limiting current plateau. As a result of the studies, a change in the complexation mechanism from hydration to "solvo-nitration" is proposed, which requires an additional potential drop within the electrochemical double layer.

Reaction Mechanisms of High‐Rate Copper Electrochemical Machining in Nitrate Electrolytes

Reaction Mechanisms of High‐Rate Copper Electrochemical Machining in Nitrate Electrolytes

Electrodeposition behaviour of samarium in 1,3-dimethyl-2-imidazolidone solvent

Abstract The present study investigates the electrochemistry spectroscopy of Sm(III), and electrodeposition of samarium metal in neutral ligand-based ionic liquid (solvate ionic liquid). Mixture consisted of a samarium precursor (either samarium triflate or samarium nitrate hexahydrate) in the solvate ionic liquid, 1.3-dimethyl-2-imidazolidone (DMI). FT-IR analysis of Sm(III)-DMI electrolytes indicates that Sm3+ ion coordinates with DMI through carbonyl group (C=O); the band splits into two with emergence of new peak at 1630 cm−1 and 1649 cm−1 for the triflate and nitrate solutions, respectively. Raman spectroscopy also confirms the solvation of Sm(III) with DMI through oxygen atom of the carbonyl group. Voltametric behaviour of Sm(III) ion indicates two-step reduction mechanism via Sm(III)/Sm(II) at ca. −2.0 V and Sm(II)/Sm(0) at ca. −3.0 V vs. Ag/Ag+ for both samarium(III)-containing electrolytes. Diffusion coefficient value of Sm(III) was determined to be 2.185 × 10−6 cm2/s and 2.418 × 10−8 cm2/s for triflate and nitrate electrolytes, respectively. Electrodeposition of samarium was achieved through constant potential electrolysis using copper substrate as the working electrode which yielded compact deposits from triflate-DMI and non-uniform granular deposit from nitrate-DMI electrolyte. Ex situ X-ray photoelectron spectroscopy analysis of the as-deposited samples revealed the presence of metallic Sm (1081 eV) co-existing with its oxide form (1083 eV).

In-situ evidence for the existence of surface films in electrochemical machining of copper in nitrate electrolytes

This contribution analyzes the electrochemical etching of copper in a sodium nitrate electrolyte using in-situ Raman spectroscopy. Experiments were conducted in a specially designed process chamber at voltages below, at, and above the limiting current plateau. Below the plateau, a Raman peak at 1050 cm–1 is detected, which is attributed to the symmetrical nitrate ion. However, the line shape changes at and above the plateau. Detailed line shape analysis indicates the presence of a copper nitrate surface film by ex-situ comparison with copper nitrate solutions. In addition, the conductivity and pH of copper nitrate solutions were determined. A 5 M copper nitrate solution exhibits a low conductivity of 55 mS cm–1 and a pH close to 0. A significant influence, especially of the low pH, on the surface structure and therefore on the etching mechanism is assumed.

A unique choline nitrate-based organo-aqueous electrolyte enables carbon/carbon supercapacitor operation in a wide temperature window (-40°C to 60°C).

Some drawbacks of aqueous electrolytes, such as freezing at low temperatures and extensive evaporation at high temperatures, restrict their industrial viability. This article introduces a stabilized neutral aqueous choline nitrate electrolyte with a 10 vol.% methanol additive that improves the temperature stability of the electrolyte via enhanced hydrogen bonding with the choline cation and water and maintains the good state of health of the supercapacitor cells under extreme operating conditions. The symmetric carbon/carbon supercapacitor in 5mol/kg choline nitrate + 10 vol.% methanol (σ = 76ms/cm at 25°C) exhibits 103F/g at room temperature during galvanostatic charge/discharge up to 1.5V, which decreases to 78F/g at -40°C due to the suppressed Faradaic reactions occurring at the carbon electrode. However, under similar charge/discharge conditions, the capacitance increases to 112F/g when the supercapacitor operates at 60°C. This capacitance increase at high temperatures is due to the Faradaic reactions related to enhanced hydrogen adsorption and desorption. The most remarkable aspect of the proposed supercapacitor is its ability to maintain capacitance and power performance during high voltage floating at 1.5V at three tested temperatures (-40°C, 24°C, and 60°C).

Fabricating Precise and Smooth Microgroove Structures on Zr-Based Metallic Glass Using Jet-ECM.

Zr-based metallic glasses (MGs) are promising materials for mold manufacturing due to their unique mechanical and chemical properties. However, the high hardness of metallic glasses and their tendency to crystallize at high temperatures make it challenging to fabricate precise and smooth microscale structures on metallic glasses. This limitation hampers the development of metallic glasses as molds. Jet electrochemical machining (jet-ECM) is a non-contact subtractive manufacturing technology that utilizes a high-speed electrolyte to partially remove material from workpieces, making it highly suitable for processing difficult-to-machine materials. Nevertheless, few studies have explored microgroove structures on Zr-based MGs using sodium nitrate electrolytes by jet-ECM. Therefore, this paper advocates the utilization of the jet-ECM technique to fabricate precise and smooth microgroove structures using a sodium nitrate electrolyte. The electrochemical characteristics were studied in sodium nitrate solution. Then, the effects of the applied voltages and nozzle travel rates on machining performance were investigated. Finally, micro-helical and micro-S structures with high geometric dimensional consistency and low surface roughness were successfully fabricated, with widths and depths measuring 433.7 ± 2.4 µm and 101.4 ± 1.6 µm, respectively. Their surface roughness was determined to be 0.118 ± 0.002 µm. Compared to non-aqueous-based methods for jet-ECM of Zr-based MGs, the depth of the microgrooves was increased from 20 μm to 101 μm. Furthermore, the processed microstructures had no uneven edges in the peripheral areas and no visible flow marks on the bottom.

Струмовий режим при електрохімічному 3d-друці виробів із міді

The peculiarities of the use of copper nitrate electrolytes in local electrodeposition or electrochemical 3D printing systems have been studied. A model of the current mode in electrochemical 3D printing has been proposed. The possibility of obtaining electrochemically 3D printed objects with a profile height up to 100 μm with a compact fine-crystalline metal structure at a current density of 2 A/dm2 in a copper nitrate electrolyte with a content of 300 g/l and with the simultaneous introduction of gloss-forming additives of the Rubin complex (KIESOW OBERFLÄCHENCHEMIE GmbH & Co) and glycine is shown.

Ammonia Electrosynthesis from Nitrate Using a Ruthenium-Copper Cocatalyst System: A Full Concentration Range Study.

Electrochemical synthesis of ammonia via the nitrate reduction reaction (NO3RR) has been intensively researched as an alternative to the traditional Haber-Bosch process. Most research focuses on the low concentration range representative of the nitrate level in wastewater, leaving the high concentration range, which exists in nuclear and fertilizer wastes, unexplored. The use of a concentrated electrolyte (≥1 M) for higher rate production is hampered by poor hydrogen transfer kinetics. Herein, we demonstrate that a cocatalytic system of Ru/Cu2O catalyst enables NO3RR at 10.0 A in 1 M nitrate electrolyte in a 16 cm2 flow electrolyzer, with 100% faradaic efficiency toward ammonia. Detailed mechanistic studies by deuterium labeling and operando Fourier transform infrared (FTIR) spectroscopy allow us to probe the hydrogen transfer rate and intermediate species on Ru/Cu2O. Ab initio molecular dynamics (AIMD) simulations reveal that adsorbed hydroxide on Ru nanoparticles increases the density of the hydrogen-bonded water network near the Cu2O surface, which promotes the hydrogen transfer rate. Our work highlights the importance of engineering synergistic interactions in cocatalysts for addressing the kinetic bottleneck in electrosynthesis.

Methods for Electrolyte Treatment and Hexavalent Chromium Reduction in Industrial Electrochemical Machining (ECM)

Electrochemical Machining (ECM) is a metal removal process that operates on the principle of anodic dissolution. ECM has the ability to produce complex shapes in difficult-to-machine alloys with precision and excellent surface finish. However, since most of these alloys contain chromium, one of the major challenges to ECM’s wider utilisation in industry is how to eliminate the resulting hexavalent chromium (Cr+6) from the spent electrolyte. This paper presents methods for controlling the Cr+6 level to within the permitted guidelines for an industry application of ECM, and reducing it to trivalent chromium (Cr+3), to then precipitating it from the electrolyte solution,The workpiece material – Triboloy (Co; Mo; Cr alloy) has hitherto not been machined by ECM and hence no literature exists on how to treat the by-products generated. This research involves experimental analysis of various Cr+6 to Cr+3 chemical reduction methods for ECM of Tribaloy in sodium nitrate electrolyte, using spent electrolyte samples. The reduction in Cr+6 is assessed over time. It was observed that the concentration of Cr+6 decreased within a span of two minutes. Subsequently, the solution pH level was increased by the addition of an alkali to precipitate the Cr+3 ions, which then can be filtered out from the solution. The optimum solution for hexavalent chromium is thus implemented in the industrial electrolyte system for successfully machining the Tribaloy component.

All-inorganic nitrate electrolyte for high-performance lithium oxygen battery

All-inorganic nitrate electrolyte for high-performance lithium oxygen battery

Further extension of the Madrid-2019 force field: Parametrization of nitrate (NO3−) and ammonium (NH4+) ions

The importance of nitrate and ammonium salts both in the environment and in biological processes cannot be questioned. In this work, using the TIP4P/2005 water model, aqueous solutions of nitrate and ammonium electrolytes are parametrized using scaled charges while keeping a rigid structure and nonpolarizable charge distributions. The models are optimized by systematically testing a set of properties for twelve electrolytes—eight nitrate and four ammonium salts—thus, enlarging the number of potential chemical species encompassed within the Madrid-2019 force field for ions. The capacity of the force field for predicting densities, ion–ion and ion–solvent structures, and transport properties of the solutions comprised by the trial batch of salts was tested and discussed. Both the dependence of the densities with the salt concentration and the solution structure were nicely reproduced by the models in the whole concentration range without any trace of precipitating events and with improved accuracy in comparison with recently reported models, while the agreement of the simulated transport properties with experimental data ranges from good to reasonable, depending on the ion/counterion pair. These scaled charge models might be considered as force fields embodying a reasonable compromise between exactness and general applicability and also as an important step in the development of accurate models for polyatomic ions.

Real-time monitoring of process current and its correlation with micro-feature accuracy and surface topography in electrochemical micromachining of nitinol

The nickel-titanium alloy known as Nitinol classified as a shape memory alloy is distinguished by its exceptional attributes, including shape memory effect, biocompatibility, and superelasticity. However, its thermo-mechanical dependent transformation behavior makes it difficult to process using traditional methods. Electrochemical micromachining (ECMM), a non-traditional fabrication method, uses anodic dissolution process to produce microfeatures on Nitinol. The current work emphasizes the impact of process current on the machining accuracy and surface topography of microchannels produced during ECMM of Nitinol utilizing ethylene glycol-based sodium nitrate electrolyte. The ECMM process parameters that were studied are pulsed potential, molar concentration, and micro-tool scan rate, and the development of the process current resulting in variation of these parameters during microchannel fabrication was closely observed. The statistical parameters, namely, the average process current and the process current fluctuation, were derived from the process current data that were further analyzed with respect to input parameters. The machining accuracy and the surface topography of the microchannel are analyzed by measuring the width overcut, channel depth, stray region, width standard deviation, and average surface roughness of the fabricated microchannel. The results showed that monitoring the process current in real-time is an effective way of controlling the process, particularly when it comes to fabricating micro-features that must adhere to strict predetermined criteria.

Preparation of Ag@lignin nanotubes for the development of antimicrobial biodegradable films from corn straw

Current environmental and energy issues have attracted considerable attention from industries, governments, and academia. Developing alternative diverse petrochemical-based plastics with biodegradable packaging materials from renewable resources is critical for ensuring both sustainability and safety. In this study, biodegradable films are fabricated from corn straw via a facile sol-gel process. Furthermore, these films are imbued with antimicrobial properties by coupling with silver@lignin nanotube hybrid antibacterial agents, formed via the in situ reduction of silver ions into elemental silver by lignin (mild reducing agent), followed by the self-assembly of lignin molecules into nanotubes assisted by an aqueous silver nitrate electrolyte solution. The developed antibacterial corn straw film exhibits strong mechanical and antibacterial properties, with a tensile strength and elongation at break of 68.7 MPa and 11.3 %, respectively, under optimum conditions and antibacterial activity against Escherichia coli and Staphylococcus aureus of 99.9 % and 97.2 %, respectively. The as-prepared corn straw films exhibit high hydrophobicity and ultraviolet resistance. The morphology, structure, and thermal properties of the corn straw films were characterized using Fourier transform infrared spectroscopy, scanning electron microscopy, energy-dispersive spectroscopy, X-ray diffraction, and thermogravimetric analysis. This study provides a straw-based biodegradable packaging film with antimicrobial properties.

Bikitaite composite polymer electrolyte for high-performance solid-state lithium metal battery

Ceramic-polymer hybrids promise to form composite electrolytes with high ionic conductivity, good stability, and electrode compatibility that conventional ceramic or polymer electrolytes cannot achieve. Using ceramic fillers in polymer electrolytes frequently results in significantly improved ion conduction. This study employs a representative composite electrolyte based on poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP), Li zeolite Li2(Al2Si4O12) (bikitaite, BKT) ceramics, and an ether-based dual salt containing Li nitrate (EDSN) electrolyte as a plasticizer. The resulting composite electrolyte composed of PVdF, EDSN, and BKT has a superior ionic conductivity of 1.03 × 10–3 S cm−1, a broader electrochemical window of 4.8 V, and a high Li transference number of 0.61. The assembled solid-state LiFePO4/Li metal battery demonstrates a long lifespan, with an outstanding capacity retention of 86% after 450 cycles at 0.3C. The developed electrolyte with long cycling stability may serve as a model for developing solid electrolytes for Li metal secondary battery applications.

Room-temperature electrochemical deposition of nanostructured ZnO films on FTO substrate and their photoelectrochemical activity

The possibility of fabrication of nanostructured ZnO layers on conductive glass substrates via simple room-temperature electrodeposition was studied in detail. The process was carried out in zinc nitrate electrolyte at different potentials for various durations. The morphology, composition, and semiconducting properties of the deposits were examined by various techniques. As-synthesized materials were found to be amorphous and co-deposition of the metallic Zn at more negative potentials was confirmed. Nevertheless, thermal treatment in air results in the successful conversion of the as-deposited precipitate to the wurtzite ZnO. The potential of −1.5 V vs. SCE was identified as optimal to achieve both full coverage of the glass substrate, as well as uniform morphology of the deposits. In general, the photoelectrochemical performance of such kind of ZnO photoanodes was found to be significantly dependent on the electrodeposition duration since this parameter strongly affected the thickness, surface morphology, as well as semiconducting properties of the obtained material. In consequence, the photoanode deposited at −1.5 V vs. SCE for 40 min exhibited the most promising photoelectrochemical activity under studied conditions.

Peculiarities of Lead Electrolysis in Nitrate Electrolytes

Peculiarities of Lead Electrolysis in Nitrate Electrolytes

Influence of Silver-Coated Tool Electrode on Electrochemical Micromachining of Incoloy 825

Incoloy 825 alloy is often used in calorifiers, propeller shafts, and tank vehicles owing to the improved resistance to aqueous corrosion. The electrochemical micromachining process can be utilized to machine such an engineering material owing to higher precision and lower tool wear. In the present study, an investigation was performed to enhance the process of creating micro-holes using silver-coated copper tool electrodes. The sodium nitrate electrolyte was used under different levels of input parameters such as voltage, electrolyte concentration, frequency, and duty cycle with a view to improving material removal rate, conicity, overcut, and circularity. It was found that silver-coated copper tool electrode had a high material removal rate (MRR), better overcut, conicity, and circularity compared to uncoated copper tools in most cases, due to its high corrosive resistance and electrical conductivity. From SEM and EDS analysis, it was observed that better surface topography of the micro-holes is obtained with silver-coated copper tool electrode while machining Incoloy 825 alloy in the micromachining process.

Mechanism of nitro-byproducts formation during persulfate-based electrokinetic in situ oxidation for remediation of anthracene contaminated soil

Persulfate-based electrokinetic (EK) chemical oxidation appears to be a novel and viable strategy for the in situ remediation of polycyclic aromatic hydrocarbons (PAHs) polluted soil; however, the possible toxic byproducts of PAHs have been overlooked. In this study, we systematically investigated the formation mechanism of the nitro-byproducts of anthracene (ANT) during the EK process. Electrochemical experiments revealed that NH4+ and NO2- originating from nitrate electrolyte or soil substrates were oxidized to NO2• and NO• in the presence of SO4•-. Liquid chromatography quadrupole time-of-flight mass spectrometry (LC-QTOF-MS/MS) analysis with 15N labeling revealed the formation of nitro-byproducts (14 kinds), including 1-hydroxy-4-nitro-anthraquinone and its similar derivatives, 4-nitrophenol, and 2,4-dinitrophenol. The nitration pathways of ANT have been proposed and described, mainly including the formation of hydroxyl-anthraquinone-oxygen and phenoxy radicals and the subsequent addition of NO2• and NO•. ANT-based formation of nitro-byproducts during EK, which is usually underestimated, should be further investigated due to their enhanced acute toxicity, mutagenic effects, and potential threat to the ecosystem.