Influence Of Electrolyte Concentration Research Articles

Influence of Electrolyte Concentration on Metal Removal Rate and Surface Finish Quality in Electrochemical Machining Masking

Electrochemical machining (ECM) is a specialized and precise manufacturing technique involving selective metal removal to achieve the desired shape or form. This article’s primary focus is examining the technical facets associated with the procedure. The elements mentioned encompass the system’s design and optimization, the electrolyte solution’s careful selection, and the precise control of the etching parameters. When considering the overall framework, it is essential to consider important factors such as the concentration of electrolytes, the operational voltage, and the value of the current flowing through the system. The main objective of this study is to evaluate the influence of different concentrations of sodium chloride electrolyte on the metal removal rate (MRR). This will be achieved by utilizing a direct current power supply. The present investigation used aluminum, steel, and stainless steel materials as the substrate for experimentation. These materials were selected to have identical dimensions for the anode and cathode. The main objective of this study is to evaluate the influence of varying concentrations (0.5, 1, 1.5, and 2 mole/liter) of sodium chloride electrolyte on the material removal rate and surface roughness. The findings have been disclosed, revealing the utmost removal rate for aluminum, steel, and stainless-steel materials across all levels of electrolyte concentration. The experimental information is currently presented, related to the rates of metal removal at various electrolyte concentrations of 2 moles per liter. The rates of mass loss observed in aluminum are comparatively higher when compared to those surveyed in steel and stainless steel. The roughness of a machined surface is inversely proportional to the concentration of the electrolyte.

Investigation of ion desolvation in aqueous electrolyte with carbon electrode via electrochemical in-situ Raman

Energy storage is an essential means to stabilize the fluctuation of renewable energy generation. Based on desolvation of electrolyte ions, high density charge storage in nanoporous electrodes has attracted widespread attention. The mechanism of ion transport within nanopores is currently under exploration. In this work, electric double layer capacitor was established using porous carbon electrode. Electrolytes with different hydrated/desolvatd ion radii were selected. The ion desolvation process was observed indirectly and concisely by using electrochemical in situ Raman technique on the carbon electrode. It was found that for ion with bigger solvation shells, its Raman intensity fluctuated with the cell charging voltage, which was caused by the desolvation of electrolyte ions. The desolvated ion has a strong polarization effect on the electron cloud of carbon. The influence of electrolyte concentrations on desolvation was also explored. High concentration electrolyte exhibits greater increase in Raman peak intensity. Our approach provides a way to study the physical mechanism and interface behavior of ion desolvation in electrochemical devices.

Experimental study of a carbon-based planar supercapacitor in an aqueous electrolyte

One of the remarkable characteristics of supercapacitors is their ability to rapidly charge/discharge compared to a battery. The increase in the charging rate adversely affects the capacitance reduction. To address this issue, a planar interdigitated electrode that provides a good rate capability is implemented. In this paper, leveraging cyclic voltammetry, we investigate the specific capacitance of three difference patterns of carbon-based planar electrodes and conventional sandwich supercapacitors using two electrodes system of cyclic voltammetry technique. The capacitance of all planar samples reach the maximum peak, which is higher than its initial value even after increasing the scan rate by 50-fold. The narrow planar electrode fringe has a strong electric field and enhances the capacitance. The optimum applied scan rate can be manipulated by varying the electrolyte concentration. Thus, a simplified model of charge storage behavior is proposed. Furthermore, the influence of electrolyte concentration and applied scan rate on the total capacitance is discussed. The excellent rate capability observed herein demonstrates the superior electrochemical performance of supercapacitor with planar electrode configuration beyond the conventional sandwich structure.

The influence of electrolyte concentration and solvent on operational voltage of Li/CFx primary batteries elucidated by Nernst Equation

Fluorinated carbons (CFx) have the highest energy density as the cathode of lithium primary battery. They demonstrate distinct behaviors in different electrolytes. While, the reaction mechanism is still unclear. In this work, the influences of electrolyte in aspects of Li-ion concentration, anion species, and solvent species on the performances of Li/CFx batteries are explored. Contrary to conventional wisdoms that electrolytes play a role as a Li-ion conductor and only limit the kinetics, we found that the electrolyte can determine its thermodynamic behavior. In detail, a lower Li-salt concentration and a solvent solvating Li+ with more molecular numbers provide higher operational voltages in Li/CFx battery. This can be well elucidated by Nernst Equation. Interesting, in Li-free electrolyte (0 M DMSO), fluorinated graphene cathode can still work, offering an impeccable specific discharge capacity of 738 mAh g−1 with a specific energy of 1968 Wh kg−1 at 0.1C.

Corrosion Experimental Research on Local Damage of Epoxy-Coated Steel Bars in Concrete Under Marine Environment

Epoxy coating has been proven to protect steel bars from corrosion. However, the damage of epoxy coating is inevitable, and this may lead to more serious corrosion of steel bar. In order to study the corrosion resistance of steel bars with damaged epoxy coating, two groups of coating-damaged bar and one group of coating-intact rebar were designed, and six specimens were made. The influence of electrolyte concentration on the corrosion rate of steel bars was studied by setting different concentrations. After 30 days of accelerated corrosion, electrochemical data were recorded by the electrochemical workstation. The experimental result shows that the steel bars with coating damage have obvious polarization curve characteristics of corrosion, and corrosion resistance decreases obviously. According to the corrosion current and potential, the larger the damaged area of the coating, the faster will be the corrosion rate. According to the polarization curve data, the polarization resistance is modified, and the result is closer to the real polarization resistance value. The calculated corrosion rate shows that the corrosion rate of reinforcement is affected by both electrolyte concentration and coating damage area, and electrolyte concentration has a greater influence on the corrosion rate.

Influence of electrolyte concentration, sodium adsorption ratio and cation combinations on relative saturated hydraulic conductivity of saline soil

Influence of electrolyte concentration, sodium adsorption ratio and cation combinations on relative saturated hydraulic conductivity of saline soil

1-D fractal model for bentonite colloid diffusion without seepage

This paper investigates the 1-D diffusion process of bentonite particle, which is affected by the friction related to the fractal structure of colloid pore. The expression of the pore tortuosity containing pore fractal dimension is deduced to determine the friction, and the evolution rule of pore fractal dimension during diffusion with bentonite volume fraction is reached. The rationality of the modified fractal model is validated via 1-D diffusion test and nuclear magnetic resonance (NMR). Then the influences of electrolyte concentration, initial volume fraction of bentonite, and surface charge density on the colloid diffusion process are analyzed. The results show that the diffusion of bentonite decreases with the increase of electrolyte concentration, and increases with the increase of initial volume fraction and surface charge density. The interfacial volume fraction is correlated with the concentration of electrolyte solution, but not with the initial volume fraction and surface charge density.

The influence of electrolyte concentration on nanofractures fabricated in a 3D-printed microfluidic device by controlled dielectric breakdown.

A three-dimensional-printed microfluidic device made of a thermoplastic material was used to study the creation of molecular filters by controlled dielectric breakdown. The device was made from acrylonitrile butadiene styrene by a fused deposition modeling three-dimensional printer and consisted of two V-shaped sample compartments separated by 750µm of extruded plastic gap. Nanofractures were formed in the thin piece of acrylonitrile butadiene styrene by controlled dielectric breakdown by application voltage of 15-20kV with the voltage terminated when reaching a defined current threshold. Variation of the size of the nanofractures was achieved by both variation of the current threshold and by variation of the ionic strength of the electrolyte used for breakdown. Electrophoretic transport of two proteins, R-phycoerythrin (RPE; <10nmin size) and fluorescamine-labeled BSA (f-BSA; 2-4nm), was used to monitor the size and transport properties of the nanofractures. Using 1mM phosphate buffer, both RPE and f-BSA passed through the nanofractures when the current threshold was set to 25 µA. However, when the threshold was lowered to 10 µA or lower, RPE was restricted from moving through the nanofractures. When we increased the electrolyte concentration during breakdown from 1 to 10mM phosphate buffer, BSA passed but RPE was blocked when the threshold was equal to, or lower than, 25 µA. This demonstrates that nanofracture size (pore area) is directly related to the breakdown current threshold but inversely related to the concentration of the electrolyte used for the breakdown process.

Influence of electrolyte concentration on static and dynamic Lead-Acid battery

Electrolyte concentration is one of the important parameters on Lead-Acid Battery (LAB) outcome. Lead-acid battery has been made with static and dynamic electrolyte treatment where 4 variations of electrolyte concentration (20%, 30%, 40% and 50%) and 1A current applied in the system during charging-discharging test to analyze the relationship of the electrolyte concentration to the battery characteristic and compare static and dynamic lead-acid battery performance. The experiment result that for dynamic lead acid battery, the capacity increases along with the higher concentration from 20% to 40% but decrease at 50% compare to 40% for 3 first cycle charge-discharge test when the static lead-acid battery unwork at concentration 20% and show the increases capacity along with increases concentration. In capacity and efficiency point of view, dynamic lead-acid show better performance compare to static lead-acid battery.

Influence of Electrolyte Concentration on Machining Characteristics of Wire ECM Finishing

Influence of Electrolyte Concentration on Machining Characteristics of Wire ECM Finishing

Fabrication of deep and small holes by synchronized laser and shaped tube electrochemical machining (Laser-STEM) hybrid process

The synchronized laser and shaped tube electrochemical machining (Laser-STEM), a hybrid machining process that combined the advantages of electrochemical machining (ECM) and laser beam machining (LBM), has been proposed and studied. The mechanisms of Laser-STEM were studied theoretically and experimentally. Mathematical model has been developed to study the effects of laser-induced thermal effects on the electrochemical dissolution rate. The influences of electrolyte concentration and laser power on the laser attenuation coefficient have been studied. Results showed that the side gap could be decreased by 62.7% and the feeding rate could be raised by 108% when utilizing Laser-STEM with a proper laser power for drilling small holes, compared with that without laser assistance. Moreover, the performance of Laser-STEM has been investigated, in terms of laser power and pulsed voltage. Experimental results showed that the machining efficiency increased with higher laser power, pulse voltage, and feeding rate, and the precision could be improved with the higher laser power and feeding rate and a smaller pulsed voltage. Finally, small holes with a diameter of 1.25 mm and free of recast layer have been fabricated on the aluminum alloy workpiece of 5 mm in thickness.

Effect of electrolyte concentration on morphological and photoluminescence properties of free standing porous anodic alumina membranes formed in oxalic acid

The free-standing porous anodic alumina membranes (AAM) were prepared in oxalic acid by varying electrolyte concentration from 0.1 to 0.9 M with a constant potential of 40 V at 8 °C. The influence of electrolyte concentration on the morphological and optical features of AAM has been studied. Regularity ratio (RR) of AAM was measured using WSxM software, highest RR obtained for AAM formed in 0.3 M. From X-ray diffraction (XRD) analysis, it was found that prepared AAM were amorphous in nature. UV–Vis absorbance spectra reveal that absorbance bands slightly moves towards the higher wavelength side with increasing electrolyte concentration. Photoluminescence (PL) of AAM has been studied and related with RR of AAM. PL measurements of AAM exhibit strong PL peak in blue region, having a slight change with increasing electrolyte concentration. PL bands were originating from two kinds of oxygen-deficient defects (F and F+), their distributions were discussed on the basis of PL spectrum.

Overlooking the obvious? Influence of electrolyte concentrations on seizure quality parameters in electroconvulsive therapy.

Clinical response to electroconvulsive therapy (ECT) depends on eliciting a generalized seizure. Though there are multiple ictal and other parameters to assess seizure quality, factors that influence these parameters have only been identified to a limited extend in antecedent studies (e.g., stimulus dosage, age). In the context of ECT, electrolyte concentrations have hardly been investigated so far-although hyponatremia is one well-known clinical factor to increase the risk of spontaneous seizures. In 31 patients with unipolar or bipolar depressive disorder, blood concentrations of sodium (Na), potassium (K), and calcium (Ca) were measured immediately prior to repeated sessions of maintenance ECT. Generalized linear mixed models were used to analyze the influence of Na, K, and Ca on seven seizure quality parameters: postictal suppression index (PSI), maximum sustained coherence (MSC), midictal amplitude, average seizure energy index, seizure duration (EEG/motor), and peak heart rate. Results show a statistically significant relationship between the serum sodium level and MSC: in the model, a reduction of 1mmol/l led to an increase in interhemispheric coherence of 0.678%. The further markers remained unaffected by changes in electrolyte concentrations. This finding provides first evidence that a lower blood concentration of sodium could enhance the quality of ECT-induced seizures in terms of higher interhemispheric coherence.

(Invited) Sensing, Measuring and Imaging Surface Charge with Nanoscale Pipettes

Charge is a fundamental interfacial property that governs physical and chemical interactions at surfaces. The workings of catalysts, sensors, separation devices, biological interfaces, and colloidal systems, are well known to be strongly influenced by surface charge, typically present in the form of protonated or deprotonated chemical moieties. Directly measuring and sensing charge in situ, especially for small (micro/nanoscale), heterogeneous charge distributions presents an interesting and important challenge for electroanalytical chemistry. Here, recent studies in mapping interfacial charge with scanning ion conductance microscopy (SICM) and the influence of electrolyte concentration on the charge sensing mechanism will be described. We have validated a SICM method that utilizes current‐voltage relationships that can be intuitively understood for surface charge detection. The effect of electrical doublelayer (EDL) thickness on signal generation on chemically modified surfaces will be demonstrated. The differential measurement approach used here allows visualization of individual domains of surface charge. EDL effects are modeled with finite element simulations, and extension of our studies to sensing at biological samples and mineral samples will be demonstrated.

Optimization of electrocatalytic H2O2 production at pilot plant scale for solar-assisted water treatment

This manuscript summarizes the successful start-up and operation of a hybrid eco-engineered water treatment system, at pilot scale. The pilot unit, with 100 L capacity, has been devised for the efficient electrocatalytic production of H2O2 at an air-diffusion cathode, triggering the formation of OH from Fenton’s reaction with added Fe2+ catalyst. These radicals, in combination with those formed at a powerful boron-doped diamond (BDD) anode in an undivided cell, are used to degrade a mixture of model pesticides. The capability of the plant to produce H2O2 on site was initially optimized using an experimental design based on central composite design (CCD) coupled with response surface methodology (RSM). This aimed to evaluate the effect of key process parameters like current density (j) and solution pH. The influence of electrolyte concentration as well as liquid and air flow rates on H2O2 electrogeneration and current efficiency at optimized j and pH was also assessed. The best operation conditions resulted in H2O2 mass production rate of 64.9 mg min−1, 89.3% of current efficiency and 0.4 kWh m-3 of energy consumption at short electrolysis time. Performance tests at optimum conditions were carried out with 75 L of a mixture of pesticides (pyrimethanil and methomyl) as a first step towards the elimination of organic contaminants by solar photoelectro-Fenton (SPEF) process. The combined action of homogeneous (OH) and heterogeneous (BDD(OH)) catalysis along with photocatalysis (UV photons collected at a solar CPC photoreactor) allowed the removal of more than 50% of both pesticides in 5 min, confirming the fast regeneration of Fe2+ catalyst through cathodic reduction and photo-Fenton reaction.

Disk-like nanocrystals prepared by solvolysis from regenerated cellulose and colloid properties of their hydrosols

One possible way of obtaining cellulose nanocrystals and aqueous sols with novel properties is based on modification of supramolecular structure of the polysaccharide. This modification involves rearrangements of hydrogen bonds and has an effect on polymer morphology, formation of surface reactive sites and interface interactions. Disc-like nanocrystals of cellulose II were prepared by solvolysis of regenerated cellulose in acetic acid/octanol medium in the presence of 0.4 mol% of phosphotungstic acid. The starting cellulose samples were dissolved and regenerated in the NaOH/thiourea system. Cellulose nanocrystals were studied by transmission electron microscopy, atomic force microscopy, dynamic light scattering, FTIR spectroscopy, XRD and thermogravimetric analysis. Colloidal stability of aqueous suspensions of cellulose nanocrystals in the presence of electrolyte (KCl) was studied. Their acid-base properties were revealed using potentiometric titration. The influence of electrolyte concentration on dynamic viscosity of the obtained hydrosols and their ability to show birefringence was established.

Study on energy consumption of Al2O3 coating prepared by cathode plasma electrolytic deposition

Al2O3 coatings with large specific surface were prepared on cast nickel-based superalloy K418 by cathode plasma electrolytic deposition (CPED) in aqueous solutions at different concentrations. The significance of energy consumption and a simple calculation method during CPED were proposed, and the influence of electrolyte concentration on current density-voltage curve, energy consumption, and microstructure of coatings were studied. It was found that increasing the concentration of electrolyte can effectively reduce the current density at the initial stage while prolonging the deposition time and stepping up the energy consumption of whole coating preparation. The morphology observation results showed that the pore size of Al2O3 coatings enlarges with the increase of the concentration, and the optimum electrolyte concentration is 0.5–1molL−1. Under this condition, the new method of oxidation pretreatment at 950℃ on samples for 30min can efficiently decrease the current density during the early stage of preparation, which is beneficial to the deposition of complex-shaped samples with large size.

Influence of electrolyte concentration on the electrochemical characteristics of LaGaO3 perovskite oxide as novel anode material for Ni/MH batteries

Abstract Recently, the ABO 3 -type perovskite oxides have been proposed as a promising novel anode for (Ni/MH) rechargeable battery due to the best electrochemical performances. In this work, LaGaO 3 perovskite was synthesized by a sol-gel technique and their physico-chemical properties for Ni/MH batteries application are tested in details under various KOH electrolyte concentrations (1 M, 3 M and 7 M). The electrochemical measurements showed that all the electrochemical parameters, such as the activation cycle number, the maximum capacity ( C max ), the hydrogen diffusion ( D H ) and the exchange current density ( I 0 ), have been greatly influenced by the variation of KOH concentration. It was found that with increasing electrolyte concentration, the activation process of this oxide was improved leading to an increase of the highest electrochemical capacity from 10 mAh g −1 (1 M) to 220 mAh g −1 (7 M). Also, the hydrogen diffusion and the current density increase with increasing KOH, which implies that increasing KOH concentration is beneficial to hydrogen diffusion process and charge transfer reaction. All the measurements revealed that the best electrochemical performances of the negative electrode are obtained at KOH 7 M.

Microfluidic Aluminum-air Cell with Methanol-based Anolyte

Aluminum-air cell, with trivalence redox couples, attracts a lot of interest to break the capacity limitation of conventional batteries in pursuit of higher mobility for portable devices. In order to overcome the self-discharge issue of aluminum, a microfluidic aluminum-air cell working with methanol-based anolyte was developed in this work. The operation feasibility of this membraneless cell was first proved. Then, the influences of electrolyte concentration and water content in the methanol-based anolyte on cell performances were investigated. Experimentally, a high discharge capacity density of 2507 mAh/g was achieved at a low current of 0.015mA.

The effect of electrolyte concentration on counter-current gas–liquid bubble column fluid dynamics: Gas holdup, flow regime transition and bubble size distributions

Electrolytes are well-known to suppress the coalescence, stabilize the homogeneous flow regime and increase the gas holdup; however, there is a lack of studies concerning the influence of electrolyte concentration on counter-current bubble column fluid dynamics. In this paper, we contribute to the existing discussion by experimentally investigating the effect of electrolyte concentration (sodium chloride, NaCl) on gas holdup, flow regime transition and bubble size distributions in a large-diameter and large-scale counter-current bubble column (5.3m in height and 0.24m inner diameter). We considered gas superficial velocities in the range of 0.004–0.20m/s and liquid superficial velocities up to −0.06m/s. Air was used as the dispersed phase and various aqueous solutions of NaCl—up to the critical concentration—were used as the liquid phase. The gas holdup measurements were used to investigate the bubble column fluid dynamics and to analyze the flow regime transition. The image analysis was applied, near the sparger and in the developed region, to study the bubble size distributions in batch and in counter-current modes. The presence of NaCl—up to a critical concentration—stabilizes the homogeneous flow regime, increases the gas holdup and shifts the bubble size distribution toward lower bubble diameters. The counter-current mode destabilizes the homogeneous flow regime when using tap water and stabilizes the homogeneous flow regime when using aqueous solution of NaCl. The results suggest that the changes in the bubble size distributions stabilize/destabilize the homogeneous flow regime and, thus, increase/decrease the gas holdup.