Interelectrode Distance Research Articles

Electrochemical reduction of aqueous nitrate using metallic silver particles as spatially suspended catalyst

Increasing nitrate concentrations in water sources is a serious concern. The current study demonstrates the electrochemical reduction of nitrate in the presence of silver metallic particles (AgMPs). Using Ti/RuO2 anode and a Ti cathode, nitrate removal in undivided and divided cells was limited to 18% and 77%, respectively, in the absence of AgMPs. Total Nitrogen (TN) removal in undivided and divided cells was nil and 29.5%, respectively, in the absence of AgMPs. Under identical conditions, the presence of 8 mM AgMPs increased nitrate removal to 63% and 99%, respectively, with significant improvement in nitrate conversion to N2. The effect of various parameters on nitrate removal and selectivity of products was studied using a divided cell: concentration of AgMPs, inter-electrode distance, cathode material, current density, initial nitrate concentration, and reusability of AgMPs. In the presence of 8 mM AgMPs, nitrate removal using different cathodes was Ti ≈ Fe > Cu > SS > Fe/Sn. The cathode type also affected the selectivity, with the maximum conversion to N2 achieved with the Ti cathode. Nitrate removal and conversion to N2 improved with the increase in current density up to 10 mA/cm2. Overall, the presence of AgMPs substantially improved nitrate removal and conversion to N2. The production of reductive species (AgHx) by the intercalation of nascent hydrogen on metallic silver appears to promote catalytic nitrate reduction. AgMPs could be reused up to 10 times with consistent performance. This work offers a new approach to nitrate reduction using an efficient and reusable catalyst.

Larger and Denser: An Optimal Design for Surface Grids of EMG Electrodes to Identify Greater and More Representative Samples of Motor Units.

The spinal motor neurons are the only neural cells whose individual activity can be noninvasively identified. This is usually done using grids of surface electromyographic (EMG) electrodes and source separation algorithms; an approach called EMG decomposition. In this study, we combined computational and experimental analyses to assess how the design parameters of grids of electrodes influence the number and the properties of the identified motor units. We first computed the percentage of motor units that could be theoretically discriminated within a pool of 200 simulated motor units when decomposing EMG signals recorded with grids of various sizes and interelectrode distances (IEDs). Increasing the density, the number of electrodes, and the size of the grids, increased the number of motor units that our decomposition algorithm could theoretically discriminate, i.e., up to 83.5% of the simulated pool (range across conditions: 30.5-83.5%). We then identified motor units from experimental EMG signals recorded in six participants with grids of various sizes (range: 2-36 cm2) and IED (range: 4-16 mm). The configuration with the largest number of electrodes and the shortest IED maximized the number of identified motor units (56 ± 14; range: 39-79) and the percentage of early recruited motor units within these samples (29 ± 14%). Finally, the number of identified motor units further increased with a prototyped grid of 256 electrodes and an IED of 2 mm. Taken together, our results showed that larger and denser surface grids of electrodes allow to identify a more representative pool of motor units than currently reported in experimental studies.

Modeling of Formation of Metal Microstructures by Local Electrodeposition on Conducting Substrate

The formation of metal microstructures on metal substrates is theoretically analyzed by the example of local silver electrodeposition using the numerical simulation of interrelated electrochemical and homogeneous chemical reactions.The distributions of the concentrations of the participants in the reactions and the current density of silver ion reduction are calculated for various concentrations of solution components and interelectrode distances. The degree of localization of metal deposition depends on the distribution of the concentrations of electroactive silver cations and the nonelectroactive complex of this metal near the anode. The conditions for reaching the maximum rate of local silver electrodeposition are determined.

Preparation of wells using an electrohydraulic drill and modeling of heat transfer processes in heat transfer elements of a heat pump

The article discusses the use of innovative electrohydraulic technology in the preparation of vertical ground heat exchangers to create heat supply using heat pumps. The discharge energy in the operating range varied E=900÷2600 J. The most economical mode of operation of the electrohydraulic installation is carried out with the following parameters: discharge voltage 30÷51 kV, capacitor bank capacity 2 µF and interelectrode distance 8÷15 mm. It is determined that the optimal energy of destruction of natural materials depends on their thickness. Based on the research, the limits of the electrophysical parameters of the approach were established, at which the concentrated destruction of hard rocks – the main stones ‒ begins. The effective amount of energy for the destruction of stones with a thickness of 53 mm is 900 J. For stones with a thickness of 78 mm, there should be 2600 J. If to increase the energy of the discharges to 1837 J, the process of complete destruction of the stones is underway. Using an electro hydraulic drill, we have prepared vertical wells up to 25 m deep. In the future, we have installed special temperature sensors along the length of the pipes, inside the well. Using a software product (Temp Keeper), data from temperature sensors are received in real time. This program allows to visually monitor temperature changes occurring at a local point. Temperature and time dependences are also obtained at coolant velocities of 0.2÷0.4 m/s. A significant decrease in the temperature in the well and at the outlet was observed at a coolant velocity of 0.35 m/s for one hour. The study conducted on the basis of the data obtained enables to achieve higher optimal drilling performance compared to conventional installations

Towards Multiphase Modeling and Simulation of Alkaline Water Electrolysis through Pore-Resolved Foam Electrodes

In today’s world, concern is growing about the future of energy. Despite very ambitious international climate goals by 2050, global energy-related carbon dioxide (CO2) emissions keep increasing. In order to tackle this problem, hydrogen (H2) might become a significant part of the solution since it is a way to produce, store, move and use energy in a clean way. However, more than 95% of the actual hydrogen production is made of grey hydrogen, e.g. H2 produced from fossil fuels, which leads to high CO2 emissions [1]. One way to decarbonise this energy vector is to use renewable energies (solar panels, wind turbines, etc.) to produce green hydrogen via water electrolysis.Among the various technologies available to perform water electrolysis, alkaline water electrolysis (AWE) is the most mature one. In general, AWE consists of two planar electrodes separated by a certain distance and operating in a liquid alkaline electrolyte solution (e.g. KOH, potassium hydroxide). Recent studies show that it is possible to significantly increase the performance of such electrolysers by substituting the traditional gap-cell design by a zero-gap cell [2,3]. To do so 3D electrodes such as foams and 3D-printed structures are used, leading to an increase of the surface area and as a result, to a higher hydrogen production rate. These 3D electrodes are incorporated between the planar current distributors at either side of a membrane or diaphragm, reducing the interelectrode distance to the thickness of the separator. In the case of traditional cells, the hydrogen bubbles will tend to evolve only from the surface of the 2D current distributor plates, while for zero-gap cells gases evolve inside the porous structure. The process can be improved even more by forcing the electrolyte flow, favouring bubble removal. Finally, a bi-layer configuration with a catalyst layer presenting high specific surface area near the separator along with a porous transport layer (PTL) allows for a very high hydrogen production in the catalyst and an easy evacuation of the bubbles through the PTL.Recent experimental results in our group validate the enhanced performance of a bi-layer foam configuration where a fine foam acts as the catalyst layer and a coarser one as the PTL. In order to have a better understanding of the electrolyte flow behaviour inside these 3D electrodes, Computational Fluid Dynamics (CFD) was used as a tool to simulate the single-phase flow numerically. The purpose of this is to determine optimal flow parameters in order to favour hydrogen bubble removal while benefiting from the high surface area of the 3D electrodes. Up to now, it appears that this kind of analysis has rarely been addressed in the literature [4].In our specific case, the foams used as the catalyst and the PTL have characteristic pore sizes of 450 µm and 3000 µm, respectively. In order to obtain an accurate geometric representation, the foams were scanned using high-resolution micro-CT (computed tomography). A computational mesh was then obtained by reconstructing the highly detailed scanned data. The incompressible Navier-Stokes equations for the single-phase flow were solved using the Finite Element Method (FEM) implemented in MigFlow software [5]. In Figure 1 we present results from a simulation with the PTL width being three times the width of the catalyst layer, and the inlet velocity 1 m/s. It appears that the electrolyte velocity in the direction perpendicular to the flow is the highest in the area close to the interface between the catalyst and the PTL, meaning that this configuration would help extracting hydrogen bubbles off the catalyst layer, towards the coarser porous region.It is important to note that the results obtained in this case were not considering the gas phase. We are currently working on the development of a multiphase pore-resolved model to see whether the assumption of optimal bubble removal is confirmed for multiphase flow. To this end, a Eulerian-Eulerian two-fluid model must be implemented for the liquid electrolyte and the gaseous bubbles. One key aspect is to correctly define closure relations for the interfacial exchange terms that appear in the momentum equations. Hydrogen bubble formation, growth and escape from the porous electrodes might also be considered. This work is a first step towards the modeling of the whole alkaline water electrolysis process through 3D porous electrodes. Figure 1

(Invited) Design and Modeling of Resistive Switching Devices for Neuromorphic Applications

Resistive switching devices are a critical component for the realization of computational systems that mimic biological neural systems. In biological systems, connection weights between the neurons are dependent on the time lapse between the neurons’ action potentials. Resistive switching devices (memristors) with multiple conductance states can mimic this biological spike-time-dependent plasticity (STDP) behaviour, with multiple conductance states being analogous to different synaptic weights. Additionally, memristors are one of the contenders as storage elements in non-volatile memories. The change in conductance in memristors can be broadly attributed to vacancy migration inside the switching layer (valence change memory) or the formation of metallic filaments inside the switching layer (electrochemical metallization).Electrochemical metallization-based memristors with vertical transport and small inter-electrode distances have been reported recently. Their device characteristics exhibit multiple conductance states with relatively low switching voltages, which makes them well-suited for low-power neuromorphic applications. Our work models the transport in these memristors, focusing on explaining and capturing their current-voltage characteristics. Our model also captures the switching dynamics (with an emphasis on estimating switching energies and delays) and explains the experimentally observed STDP behaviour in these devices. We have proposed models for filament growth and dissolution along one dimension (axial) and two dimensions (axial and radial). The simulation results obtained using our model (and implemented in Verilog-A) have been validated with experimental data from multiple sources. Our work demonstrates the flexibility of including different transport mechanisms in a unified framework.We have characterized valence change memory (VCM) memristors with HfO2 and HfZrO2 as switching layers. They exhibit bipolar switching, negative differential resistance, multiple conductance states, and STDP behaviour, which have been analyzed. We have also modeled the transport in these VCM-based memristors, and simulated the I-V and dynamic switching characteristics, and STDP behaviour in these devices. We have simulated arrays of, both, ECM and VCM devices using the proposed models, and tried to demonstrate a typical pattern classification problem using in-memory computation. We believe that our models provide useful insight into the design of memristors for neuromorphic and memory applications.

Electrodynamic suspension of particles with finite electrical conductivity

The electrodynamic suspension of micrometric inertialess particles with finite electrical conductivity in the gap between two parallel horizontal electrodes subjected to a DC potential difference is analyzed in a collision-dominated regime in which the mean free path between particle collisions is small compared with the interelectrode distance. Operation with a constant number of suspended particles and with an excess of particles deposited on the lower electrode are modelled. Stationary solutions in a laterally unbounded gap are computed and their linear stability is analyzed. In both cases, these solutions become unstable when the number of suspended particles increases, and they transition to time dependent solutions. Numerical computations show that particle and charge accumulations develop at the lower electrode and eventually become electrohydrodynamic plumes rising across the gap. The electric current carried by the suspended particles from the lower to the upper electrode is a rapidly increasing function of the particle conductivity.

Phosphorus removal and recovery from anaerobic bioreactor effluent using a batch electrocoagulation process

Abstract A batch monopolar electrocoagulation system was developed and studied for the removal of phosphorus from anaerobic bioreactor effluent using iron as an electrode material. The study focused on the optimization of the independent variables, such as initial pH, retention time (RT), current density (CD) and inter-electrode distance (IED) using the response surface methodology (RSM) to maximize the removal of total phosphorus (TP). A quadratic model was fitted to the experimental data for TP removal. The optimal parameters were found to be pH of 6.75, RT of 11.06 min, CD of 300 A/m2, and inter-electrode distance of 1.5 cm resulting in 98.05% TP removal and energy consumption of 1.28 kWh/m3. A kinetic study for TP removal revealed that at optimal conditions, removal followed first-order kinetics (K = 0.185 m/min). Phosphorus was recovered from the post-precipitated sludge through combustion at 900 °C followed by acid leaching with sulfuric acid. Acid leaching tests were carried out with sulfuric acid for the post-precipitated sludge obtained at the optimum conditions. It resulted in around 91% of phosphorus recovery at a liquid-to-solid ratio of 100 mL/g.

Cyanide effluent treatment by electrocoagulation using airlift reactor: Modeling and optimization by response surface methodology

The extraction processes of gold, silver, and various metals from ores consume 13% of 1.1 million metric tons of hydrogen cyanide produced worldwide annually. Therefore, developing efficient processes to treat the issuing effluents before releasing them into the environment is imperative. In this context, the present study aims to evaluate the effect of three factors: inter-electrodes distance (d), current density (J) and electrolysis time (t) on the cyanide removal efficiency by a combination between Electro-Coagulation process and Internal Loop Airlift Reactor. Employing an airlift reactor enables an effective dispersion of the coagulant without the need for additional stirring. The optimization of the process was conducted using Response Surface Methodology in conjunction with Box–Behnken Design. The statistical analysis results reveal that electrolysis time(t)and current density (J) have significant effects on reactor performance to reduce cyanide with a confidence level of 99%, and 97.5%, respectively. The multiple regression analysis method demonstrates the model's overall predictability as the coefficient of determination was 98 % for the cyanide removal efficiency. The investigation inside the RSM 2 and 3-dimensional graphs allowed us to define the optimal domains of the variables to reduce cyanide. At a current density of 68 A.m−2 and an inter-electrodes distance of 13mm during 57.5min of electrolysis time, 98.27% of cyanide removal is achieved. The knowledge obtained through this study using the airlift reactor operating in batch mode and the EC process for the treatment of cyanide effluent confirms EC's ability to successfully remove cyanide and might be useful for the transposition from batch to continuous mode.

A 1D model for prediction of dry electrical discharge machining (dry-EDM) plasma characteristics

This paper introduces a one-dimensional (1D) model for predicting the properties of electrical discharge machining (EDM) plasma in the air as the dielectric medium. The model solves the governing equations of particle balance (drift-diffusion) and energy balance to determine key plasma properties, including electron and chemical species density, plasma temperature, plasma potential and current, plasma conductivity, and heat flux to the electrodes, as a function of axial inter-electrode distance and time. Validation studies are conducted using experimental data from the literature to assess the reliability of the model. Specifically, the electron density, plasma temperature, plasma voltage, and discharge current are compared between the model predictions and experimental measurements from the literature, demonstrating the model’s accuracy in capturing complex plasma behavior. Simulation experiments are performed to investigate the impact of two key process parameters, the open gap voltage and inter-electrode gap, on the plasma characteristics. The model offers valuable insights into the effect of these parameters on heat flux and energy consumption during the dry-EDM process, which can lead to improved productivity and energy efficiency.

Electrohydraulic Crimping of Tubes within Rings

Crimping processes are commonly used in industry to join two tubular parts together. In the case of positive clearance crimping, one of the two parts must be plastically deformed to fill the initial clearance and block elastic deformations in the second one. The strength of the assembly will then depends on the residual contact pressure established at the interface. Quasi-static processes are the most commonly used to perform these operations, but over the past two decades, there has been a growing interest in the use of dynamic crimping by magnetic pulse. Processes that generate high-strain rate allow to reduce the springback, which is of great interest for crimping. However, its use is limited if the part to be deformed is made of a poor electrical conductor material or if its dimensions are too small. This paper presents an alternative for dynamically crimping tubes within rings using electrohydraulic process. An experimental equipment has been designed to guide and amplify pressure waves to the area to be deformed. Two amplifiers called acoustic and mechanical pulse shapers (APS and MPS) have been tested and allow to reach hoop strain rate at about 1000 and 100 s−1 respectively. An analytical model was also built allowing to define the stored energy and the inter-electrodes distance to maximize the pressure. Results of push-out tests are also presented and demonstrate the ability of the electrohydraulic crimping process coupled with the MPS to crimp small 316L tubes into rings made of the same material, but achieving crimping successfully with the APS still require further work.

Assessment of the Interelectrode Distance Effect over the Omnipole with High Multielectrode Arrays.

The development of high-density multielectrode catheters has significantly advanced cardiac electrophysiology mapping. High-density grid catheters have enabled the creation of a novel technique for reconstructing electrogram (EGM) signals known as "omnipole," which is believed to be more reliable than other methods, especially in terms of orientation independence. This study aims to evaluate how distance affects the omnipolar reconstruction of EGMs by comparing different configurations. Using an animal set up of perfused isolated rabbit hearts, recordings were taken using an ad hoc high-density epicardial multielectrode catheter. Inter-electrode distances ranging from 1 to 4 mm were analysed for their effect on the quality of resulting EGMs. Two biomarkers were computed to evaluate the robustness of the reconstructions: the areas contained within the bipolar loops and the amplitudes of the omnipoles. We hypothesised that both bipolar and omnipolar electrograms would be more robust at shorter inter-electrode distances. The results showed that an increase in distance triggers an increase in loop areas and amplitudes, which supports the hypothesis. This finding provides a more reliable estimate of wavefront propagation for the cross-omnipolar reconstruction method. These results emphasise the importance of distance in cardiac electrophysiology mapping and provide valuable insights into the use of high-density multielectrode catheters for EGM reconstruction.Clinical Relevance- The results of this study have direct clinical relevance in the application of the described techniques to recording systems in the cardiac electrophysiology laboratory, enabling clinicians to obtain more precise characterisation of signals in the myocardium.

Cathodic microenvironment reconstruction boost electrocoagulation treatment of photovoltaic wastewater

Electrocoagulation has emerged as a rapidly advancing area in the field of wastewater treatment due to its capability to eliminate pollutants that are typically resistant to filtration or chemical treatment methods, as well as its overall effectiveness, which is often impeded by the formation and growth of flocs. In this study, simulated photovoltaic wastewater was treated using the electrocoagulation method, with cathodic water reduction employed to induce a highly efficient electrocoagulation rate towards the removal of SiO2 and F−. Our results demonstrate that the optimal conditions for this process involved the use of an Al anode, Nickel foam as cathode, an inter-electrode distance of 1.0 cm, a current density of 30 mA cm−2, a stirring speed of 300 rpm, sodium chloride as supporting electrolyte, and an initial pH of 7. Our experimental findings indicated satisfactory performance with respect to EC, as evidenced by the reduction of F− content from 25 mg L−1 to 3.68 mg L−1, and the complete removal of SiO2 from 16 mg L−1. Furthermore, electrochemical analysis and texture characterization revealed that the overall rate of flocculation was dependent on the cathodic material, with in-situ generated OH− in the electrolysis cell influencing the microenvironment of iron hydroxide floc formation and sedimentation. Our study offers conclusive evidence that the optimal cathodic material capable of intensifying OH− concentration from water dissociation is key to achieving superior electrocoagulation performance.

Electrochemical treatment of wastewater containing urea-formaldehyde and melamine-formaldehyde

The wastewater containing urea-formaldehyde (UF) and melamine-formaldehyde (MF) from the medium-density fiberboard (MDF) lamination factory disposed into the waterbodies adversely affects human health and aquatic life. Therefore, its treatment before discharge is necessary. Researchers have used various techniques to treat this type of wastewater in the past, but none have tried electrochemical (EC). However, EC can potentially remove pollutants such as chemical oxygen demand (COD), total organic carbon (TOC), formaldehyde (FA), total nitrogen (TN), nitrogen nitrate (NO3–N), and other hydrocarbons. Hence, this study uses the EC technique to treat wastewater containing UF and MF with aluminium electrodes. The experiments were run in batch mode with a 250 mL working volume in a 500 mL Pyrex glass beaker using a variable DC power supply (0–30 V and 0–5 A). The impacts of various parameters, including reaction time (RT) 30–240 min, current density (CD) 8.66–51.94 mA/cm2, inter-electrode distance (IED) 1–2 cm, and mixing speed in the range of 60–120 rpm were examined to achieve the best pollutant removals. The best removal percentage was reached at the optimized conditions of 150 min RT, 43.28 mA/cm2 CD, 1.5 cm IED, and 80 rpm: 81.1% TOC, 61.5% COD, 76.7% TN, 28.3% NO3–N, and 55.2% FA. During the EC process, electrodes and energy consumption were estimated at around 2.367 (g/L) and 0.18 (kWh/L), respectively. A kinetic analysis was also carried out to determine the pollutant's removal trend. This study concluded that the pseudo-first-order kinetic model was the best fit for removing TOC and FA with regression coefficients of 0.96 and 0.83, respectively.

Combined ozone, photo, and electrocoagulation technologies-An innovative technique for treatment of distillery industrial wastewater

Electrocoagulation with ozone and photo is a hybrid electrochemical and AOP techniques used to treat wastewater and industrial effluent. In the present study, the effects of combining O3, UV, and EC processes on color removal as well as the related COD removal and EEC from the treatment of DIW were assessed. The results showed that, compared to other hybrid processes like O3/EC, UV/EC, UV/O3, and single processes of EC, O3, and UV, the combined process of O3/UV/EC is significantly more effective for treating DIW in terms of COD removal (98.99%) and complete color removal with a required EEC of 9.7 kWhr m-3. Number of process variables, including reaction time (1 to 5 hr), O3 (0.8 to 4 g L-1), UV (8 to 32 W), current density (0.08 to 0.23 A dm-2), pH (1 to 11), COD (1000 to 6000 mg L-1), inter-electrode distance (0.75 to 3.75 cm), and combination of electrodes were studied to analyze how they affected. The optimum operating circumstances underwent testing and shown outstanding effectiveness in eliminating the COD and determination of EEC from DIW. Overall, it was clear from the results that combined treatment approaches could be more effective in removing the pollutant successfully from DIW.

How far does electrical stimulation activate white matter tracts? A computational modeling study

ObjectiveThe aim of this study was to model how the different parameters of electrical stimulation (intensity, pulse shape, probe geometry) influence the extent of white matter activation. MethodsThe electrical potentials generated by the stimulating electrodes were determined by solving Laplace equation. The temporal evolution of membrane potentials at each nodes of Ranvier of an axon was then computed by solving the coupled system of differential equations describing membrane dynamics and cable propagation. ResultsRegions of unilateral propagation were observed for monophasic pulses delivered with a bipolar probe aligned along the tract. For biphasic pulses, the largest activation areas and depths were found with a high inter-electrode-distance (IED) bipolar probe, oriented orthogonally to the tract. The smallest activation areas and depths were found for bipolar stimulations with the probe aligned parallel to the tract and low IED. For isotropic white matter regions, the activation area and depth were three times larger than for anisotropic white matter tracts. ConclusionsBipolar probes with biphasic pulses offer the greatest versatility: an orthogonal orientation acts as two monopolars (increased sensitivity when searching for a tract), whereas a parallel orientation corresponds to a single monopolar (increased specificity). Activation is more superficial when stimulating highly anisotropic tracts. SignificanceThis knowledge is essential for interpreting the behavorial effects of stimulation and the recordings of axono-cortical evoked potentials.

Electrocoagulation treatment of paint wastewater from equipment cleaning and conversion of by-product sludge into nano-pigment

This work aims to treat paint wastewater from industrial equipment cleaning by electrocoagulation (EC) using aluminum electrodes and reusing residual sludge as a starting material for synthesizing a blue inorganic nano-pigment. An initial pH of the wastewater without adjustment, a current density of 133.33 A/m2, an electrolysis time of 30 min and an inter-electrode distance (IED) of 2 cm were the best operating conditions for EC. The reduction rate of COD and turbidity was about 92% and 99.6%, respectively. At optimum conditions, specific metal consumption and specific electrical energy consumption are about 0.168 kg/m3 and 15 kWh/m3, respectively. The paint wastewater treatment sludge (PWTS) from EC was first characterized and then mixed with cobalt(II) chloride to synthesize an inorganic blue nano-pigment. The effects of Co/Al molar ratios and temperatures were studied. From colorimetric data, the pigment obtained at 1100 °C is more bluish than those synthesized at a lower temperature. This study will have beneficial effects on the environment as well as on the economy because it makes it possible to transform PWTS into value-added products. Treated wastewater can be reused for paint equipment cleaning and EC sludge can be completely transformed into pigment. The zero-waste principle can therefore be achieved.

Plating and Stripping of Lithium Metal Stabilized by a Block Copolymer Electrolyte: Local Current Density Measurement and Modeling

Plating and stripping of lithium protrusions in lithium metal symmetric cells containing a solid block copolymer electrolyte was studied as a function of time in 3D using time-resolved X-ray tomography. These measurements enabled determination of the spatial variation in current densities at the plating and stripping electrodes. The initial interelectrode distance was 27 μm. Correlation functions were calculated to reveal the relationships between current densities at the two electrodes and local electrolyte thickness. Current densities at opposing electrode locations during protrusion growth is uncorrelated until the local interelectrode distance decreases to less than 6 μm, just before the cell shorts. Mass balance was used to determine the area from which lithium ions that form a protrusion were stripped. Computational modeling of the plating and stripping process reveals the interplay between electrochemical and mechanical driving forces and their effect on nonuniform current distribution. Model predictions were compared with experiments without resorting to any adjustable parameters. The computed correlation functions were in qualitative agreement with experiments. Finally, the model was used to calculate contour plots of electrochemical potential within the electrolyte, shedding light on how geometry, salt concentration, interelectrode distance, and mechanical stress influence local rates of electrochemical reaction.

A research of the effect of an underwater electric explosion on the selectivity of destruction of quartz raw materials

The work is devoted to the study of the effect of an electric explosion on the selectivity of the destruction of quartz raw materials. The object of the study is quartz ore of the Nadyrbay deposit of the Republic of Kazakhstan. An electrohydroimpulse plant for crushing and grinding quartz raw materials has been developed and assembled. Using the electrohydroimpulse method, the granulometric composition of quartz can be adjusted. This makes it possible to adjust the magnitude of the voltage in the discharge channel and time. In this technology, quartz ore processing was carried out with an increase in the discharge voltage of the storage from 14 kV to 25 kV, the length of the interelectrode distance from 8 to 12, the capacitance of the capacitor 0.5 µF, 0.75 µF and the processing time of 5 min. Using the electrohydroimpulse method, quartz ore particles with an initial fraction of 5 mm, 10 mm and 1 mm were crushed to 0.8. The results of the grinding of quartz raw materials with the influence of an underwater electric explosion in a liquid medium allowed us to determine the degree of grinding of the material. The obtained results can be used in the course of studying the characteristics of crushing and grinding of ores. In the food industry, quartz sand within 0.25–0.5 millimeters can be used as a filler to create filters for water purification, as well as products from oil, industrial effluents, etc. Particles ranging in size from 0.5 to 1 millimeter can be used for rough processing of metal, stone and glass. The structural and quantitative analysis of powdered quartzite samples was made using a scanning electron microscope and the stoichiometry of the elements was calculated

Multi-walled carbon nanotube-functional ionophore based composite potentiometric sensor for selective detection of lead in water

A functional ionophore (tetramethyl thiuram disulfide or TMTDS) and multi-walled carbon nanotubes (MWCNTs)-based composite paste was prepared by a novel and simple approach, to fabricate a two-electrode system for detection of lead ions in drinking water, by potentiometric method. Homogenous and properly dispersed paste was obtained by blending TMTDS and MWCNTs powder in silicon oil. The working electrode contained the ionophore and the potential between working and reference electrodes were used for assessing performance of the proposed sensor. Effect of various operating conditions, such as, concentration of TMTDS in working electrode, solution pH, temperature, inter-electrode distance and sensing time was carried out to obtain the best sensor. Highest sensitivity was achieved at 24 wt% TMTDS concentration, neutral pH, room temperature (298 K), 2-minute sensing time and 0.5 cm inter-electrode spacing. Following this, the best sensor was used for electrochemical characterization, such as, impedance spectroscopy, cyclic voltammetry, chronoamperometry and differential pulse voltammetry at different lead concentrations. Studies were also performed to show the content of different ions in the leachate solution from the prepared electrode. Compared to other conventional electrodes, synthesized composite paste-based electrode displayed significant enhancement in selective determination of lead. Proposed method offers scope for on-site detection of lead ions, even at trace levels, ranging from 0.2 μg/l till 150 μg/l. Sensitivity of the sensor toward lead ions was calculated and a detection limit of 31 μg/l was observed.