Effects Of Electrolyte Solutions Research Articles

Effect of electrolyte solutions on the electrochemical dissolution behavior of additively manufactured Hastelloy X superalloy via laser solid forming

The electrolyte solution significantly affects electrochemical machining. This study investigates the electrochemical dissolution behavior of a laser solid formed Hastelloy X nickel-based superalloy in 15 wt% NaNO3, 7.5 wt% NaNO3 + 7.5 wt% NaCl, and 15 wt% NaCl solutions. The Cl- ions in the electrolyte solution accelerates the passive dissolution rate because the electrochemical reactions at the metal/film and film/solution interfaces are promoted. During the transpassive dissolution process, the Cl- ions in the electrolyte solution weaken the hindering effect of the transpassive film on the dissolution process, resulting in a faster transpassive dissolution rate and a higher current efficiency. Furthermore, the flatness of the dissolved surface in the chloride-containing solution is significantly higher than that in the chloride-free solution. Two models are proposed to illustrate the passive and transpassive dissolution behaviors. This study provides theoretical guidance for the selection of electrolyte solutions for the electrochemical machining of laser solid formed nickel-based superalloys.

Corrosion of copper alloys in KOH, NaOH, NaCl, and HCl electrolyte solutions and its impact to the mechanical properties

Effects of electrolyte solution (i.e., KOH, NaOH, NaCl, and HCl) with various concentrations (from 0 to 0.71 M) on corrosion and mechanical properties of the copper alloys were investigated. Experimental results showed that the increases in the concentration of electrolytes allowed faster corrosion process. However, too high concentration of electrolytes has no further impacts on the corrosion profile due to the existence of the passivity phenomena on the surface of the material, preventing the material to get more corroded. Acidic (HCl) and salt (NaCl) electrolytes gave more impacts on the corrosion compared to the alkaline solution (i.e., NaOH and KOH) since the acidic and salt ions are able to destroy the formed passivation layer. The correlation of the corrosion rate and the mechanical properties was also presented, in which the increases in the corrosion rate were in line with the decreases in the mechanical properties (i.e., tensile and yield strength). During the corrosion, the atomic structure in the material received attacks from the electrolyte ions, making the structure inside the copper alloys to be less strong and easily fatigued. Understanding the corrosion process and mechanical properties is important for further applications of copper-related alloys in extreme and severe conditions.

Effect of electrolyte solution and deposition methods on TiO2/CdS core–shell nanotube arrays for photoelectrocatalytic application

In this work, TiO2 nanostructure thin films were deposited by using anodization technique, while CdS thin films were deposited on TiO2 films by two methods chemical bath deposition (CBD) and successive ionic layer adsorption and reaction (SILAR). The structure of TiO2/CdS films were investigated and analyzed by XRD, SEM, and AFM, but the optical properties were investigated by UV–visible spectroscopy, PL spectroscopy, and spectral response. XRD analysis of all deposited films has confirmed the formation of two phases one is tetragonal phase (anatase, and rutile) for TiO2, and second hexagonal phase which belong to CdS layer. SEM images of TiO2 nanotubes arrays (NTAs)/CdS showed the TiO2 NTs walls become decorated with aggregates of fine CdS nanoparticles that partly penetrate into the TiO2 NTAs pores. AFM measurements displayed increase in the surface roughness compared with TiO2 films. PL measurement results of TiO2/CdS core–shell show two peaks, one is located at UV-region pointed to energy band gap for TiO2 nano films, and second one is located at visible region pointing to recombination of photogenerated electron–hole pairs within CdS layers. Spectral response measurements showed photocurrent peaks for all TiO2/CdS films deposited with different electrolyte solution have red-shift to visible region. When illuminated with a UV–Vis light source, the TiO2/CdS core–shell films displayed high response. A higher response to UV–Vis light was attained with the use of TiO2 NTAs/CdS films prepared by anodization /CBD. This approach offers a technique for fabricating photoelectrodes.

Salting Out Effect of Electrolyte Solutions in The Extraction of Tantalum and Niobium Using Aqueous Biphase System

The salting-out effect of various solutions of electrolyte in the extraction of tantalum and niobium using aqueous biphasic system (ABS) was investigated. This was achieved by leaching ball-milled Tantalite ore with mineral acids (H2SO4 and HF) in the ratio of 3:1. The leached liquor was then divided into five parts and each part mixed with ABS formed (e.g. PEG-3350/20wt/wt Na2CO3) for the extraction of tantalum and niobium and then with Na2SO4, K2CO3, K2SO4, KBr, and KI salts in turn. The amount of tantalum pent oxide extracted was determined using X-ray fluorescence method. The results show that the percentage tantalum extracted was in the range of 28.17% to 54.93% i.e. increased in the order KI< KBr < K2CO3< Na2SO4, < K2SO4 with 28.17%, 30.28%, 34.51%, 43.31% and 54.93% respectively; while that of niobium pent oxide increased in the order KI< KBr < K2CO3< Na2SO4, < K2SO4 with 27.3%, 29.35%, 33.78%, 34.64% and 41.98% respectively. In conclusion electrolyte with high ionic charge and hydration radius salts-out Ta2O5 better in the ABS/electrolyte system than those with low values.

Effects of Electrolyte Solutions and Their pH on the Electrochromic Cycling Stability of Reactively Sputtered WO3 Thin Fims

WO3 thin films were prepared by reactive sputtering and their electrochromic (EC) cycling characteristics were examined in aqueous electrolyte solutions with a pH range from 1 to 6. These solutions contained H2SO4 and a supporting electrolyte of either, K2SO4 or Na2SO4, which was added to maintain a constant ionic conductivity. Stable EC cycling was achieved in solutions containing K2SO4 with pH from 1.5 to 3.6, whereas some degradation occurred in solutions containing Na2SO4. In neutral solutions, the WO3 films peeled off within 20 cycles, regardless pf the type of electrolyte. A maximum transmittance change from 38 to 90%, and stable EC cycling up to 100 cycles were obtained in acidic electrolytes containing H2SO4 + K2SO4 with a pH of 1.5 to 2.5.

Effects of Electrolyte Solutions and Their pH On the Electrochromic Cycling Stability of Reactively Sputtered WO3 Thin Fims

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Hardness enhancement of PEO-treated Mg alloy for biodegradable implants

In recent times, magnesium alloys have emerged as a possible biodegradable implant material. Plasma electrolytic oxidation (PEO) has been used in the past as a useful surface treatment technique to improve wear resistance and corrosion resistance of magnesium alloys by forming protective coatings. This study focuses on the effect of electrolyte solution on the microstructural and nanomechanical behavior of PEO coatings for possible use in biodegradable implants. Microstructural characterization of the coating was carried out by X-ray diffraction (XRD), scanning electron microscopy followed by image analysis and energy dispersive X-ray spectroscopy. Furthermore, nanoindentation was used to evaluate nanohardness of the PEO coatings. The results show beneficial effects of the PEO coating to improve the hardness of the uncoated AZ31 magnesium alloy. The XRD pattern shows that the crystal structures of the film vary based on electrolyte solution and the effect that has on nanomechanical behavior. In conclusion, this article shows the possible benefit of PEO coating for biodegradable implant use.

A comparative study of anodized titania nanotube architectures in aqueous and nonaqueous solutions

Abstract

Effect of Electrolyte Solutions on the Adsorption of Surfactants at PTFE−Water Interface

Adsorption of ionic and nonionic surfactants on low surface energy hydrophobic PTFE−water interfaces in the absence and presence of electrolytes have been studied here. The objective of this study is to see the surfactant adsorption behavior in the presence of electrolytes that may reduce the consumption of surfactants. The kinetics of adsorption fits well pseudo-second-order kinetic model for the three surfactants studied here. Adsorption isotherms of TX-100 follow Langmuir type, whereas sodium dodecylbenzene sulfonate (SDBS) and cetylpyridinium bromide (CPB) follow Freundlich type. However, in the presence of electrolytes both the ionic surfactants show better fitting with Langmuir type isotherm. The effect of electrolytes on the surfactant concentration far below the CMC shows there is a linear increase in amount adsorbed with the increase in ionic strength of the electrolyte mainly due to reduction in headgroup repulsion and finally reaches a plateau level when the equilibrium concentration reaches CM...

Ionic transport phenomenon across sol–gel derived organic–inorganic composite mono-valent cation selective membranes

Organic–inorganic composite mono-valent cation selective membranes (MCSMs) were prepared by sol–gel under acidic conditions, in which sulfonic acid groups were introduced at the inorganic segment. Studies on physicochemical and electrochemical properties revealed their excellent mechanical, thermal, and oxidative stabilities, high conductivity, ion-exchange capacity, permselectivity for mono-valent cations, ionic diffusion and water transport number. These properties suggested the suitability of MCSMs, especially Si-65%, for electro-separation of Na + from Ca 2+, Mg 2+, and Fe 3+. The effect of electrolyte solution on the characteristics of the current–voltage ( i – v ) curve in MCSM was studied based on the concentration polarization. Electro-transport of different ions in terms of plateau length and concentration profiles for different ions in the solution phase, diffusion boundary layer and membrane phase were presented. Information obtained from i – v curve analysis were validated by electrodialysis (ED) experiments for individual or mixed electrolyte solutions. Electro-transport efficiency and separation factor of different ions for MCSM and Nafion117 (N117) membranes were compared, which suggested suitability of MCSMs for separating cations.

Solid-phase microextraction using poly(pyrrole) film and liquid chromatography with UV detection for analysis of antidepressants in plasma samples

Poly(pyrrole) (PPY) coating was prepared on a stainless-steel (SS) wire for solid-phase microextraction (SPME) by electrochemical deposition (cyclic voltammetric). The PPY was evaluated by analyzing new-generation antidepressants (mirtazapine, citalopram, paroxetine, duloxetine, fluoxetine, and sertraline) in plasma sample by SPME and liquid chromatography with UV detection (LC-UV). The effect of electrolyte solution (lithium perchlorate or tetrabutylammonium perchlorate) and the number of cycles (50, 100 or 200) applied during the polymerization process on the SPME performance was evaluated. Important factors in the optimization of SPME efficiency such as extraction time, temperature, pH, influence of plasma proteins on sorption mechanisms, and desorption conditions are discussed. The SPME–PPY/LC method showed to be linear in concentrations ranging from the limit of quantification (LOQ) to 1200 ng mL −1. The LOQ values range from 16 to 25 ng mL −1. The inter-day precision of the SPME–PPY/LC method presented coefficient of variation (CV) lower than 15%. Based on analytical validation results, the SPME–PPY/LC methodology showed to be adequate for antidepressant analysis, from therapeutic to toxic levels. In order to evaluate the proposed method for clinical use, the SPME–PPY/LC method was applied to the analysis of plasma samples from elderly depressed patients.

Distribution of Ion Species and Formation of Ion Pairs in Concentrated Polysulfide Solutions in Photoelectrochemical Transducers

Results of spectrophotometric measurements in concentrated polysulfide solutions used as electrolytes in regenerative photoelectrochemical transducers are presented. The equilibrium constants are determined and the distribution of ions species in the solutions is calculated. The effect of electrolyte solution on the output characteristics of a photoelectrochemical cell based on cadmium selenide and cobalt sulfide was studied.

Effects of Electrolytes on the Transport Phenomena in a Cation-Exchange Membrane

The effect of electrolyte solutions on the characteristics of the current–voltage (I–V) curve in a cation-exchange membrane (CMX membrane, Tokuyama Soda, Inc.) was studied based on the concentration polarization and electroconvection theory. The study includes the limiting current density (LCD), plateau length, and the ratio of resistance of region III to region I of the I–V curve (R3rd/R1st). Different electrolyte solutions, HCl, LiCl, NaCl, KCl, CaCl2, MgCl2, and AlCl3, were used in this study. The LCD values of the electrolytes were correlated with the diffusion coefficient of the cation (D+) and valence of the cation and anion (z+, z−). Except for the HCl solution, the LCD values of the electrolytes increased linearly with D+(1−z+/z−), implying that the current in this region was governed by the concentration polarization phenomena. The deviation of the HCl solution from the linearity is due to a particular transport mechanism of the proton called the Grotthuss-type transport. The differences in the plateau length and the resistance ratio, R3rd/R1st, with the electrolytes were explained by the Péclet number (Pe) representing a transport pattern in the electroconvection theory. The Péclet number is proportional to the Stokes radius of an ion. An electrolyte with a large Stokes radius has a shorter plateau length and a lower ratio of R3rd/R1st than those of an electrolyte with a small Stokes radius. Water-splitting measurements for the different electrolyte solutions in the CMX membrane revealed that the contribution of water splitting to the overlimting current was insignificant regardless of the electrolytes used in this study. However, when metal hydroxides, such as Al(OH)3, formed on the surface of the membrane, significant water splitting was observed.

The nature of specific adsorption of some halogen ions on mercury electrode. Quantum—mechanical approach

A model of a surface of liquid mercury electrode in the frame of thin film theory has been proposed. From the point of view of thin film approach the chemisorption problem was formulated. An attempt to explain the nature of specific adsorption on a molecular level is given. The effect of electrolyte solution at the interface is simplified; ie a boundary condition acting on the electrode surface. Based upon this theory of an electrode surface there is also the photoemission phenomenon. There is also an example of conversion of the theoretical results to those experimentally obtained.

Effect of electrolyte solution on saturated hydraulic conductivity of soils varying in clay type and content, and iron oxides

AbstractChanges of hydraulic conductivity (HC) at electrolyte solutions having different combinations of sodium adsorption ratio (SAR)1 and electrolyte concentration (EC), were monitored in soil columns packed with samples from Rhodustalf, Chromustert, Andic Eutropept and Oxic Rhodustult, four subtropical soils varying in clay type and content, and iron oxides. In general, it was observed that the HC dropped with the decrease of EC and with the increase in SAR of solutions, or, with the increase in exchangeable sodium percentage (ESP) of the soil. In montmorillonitic soils the reduction of HC had been most pronounced, while the kaolinite‐rich soils showed only an insignificant drop in HC even at the highest SAR coupled with the lowest EC. The improvement or revival of HC from its final drop was examined upon leaching the soil columns finally with the initial high concentration solution. Montmorillonitic soils showed moderate to high revival of HC, while for montmorillonite‐illite‐kaolinite mixed clayey soils and kaolinitic soils the improvement of HC was low and practically nil respectively. The percentage revival of HC from its final drop was employed as a criterion to assess the major cause of HC reduction and it was found that irrespective of clay mineralogy “dispersion and subsequent pore plugging” played a major role in reducing the HC of soils, though in montmorillonitic soils swelling had been found to be an almost equivalent additional cause of HC drop. Simple correlations (r) between the saturated HC at varying SAR &amp; EC and different physico‐chemical and mineralogical properties have been calculated and its role and implications have been discussed.

Effect of electrolyte solutions on the unsaturated hydraulic conductivity of a sodic clay soil : Scotter, D R Aust J Soil ResV23, N2, 1985, P301–307

Effect of electrolyte solutions on the unsaturated hydraulic conductivity of a sodic clay soil : Scotter, D R Aust J Soil ResV23, N2, 1985, P301–307

The effect of electrolyte solutions on the unsaturated hydraulic conductivity of a sodic clay soil

A technique for measuring the effect of different electrolyte solutions on the unsaturated hydraulic conductivity of low permeability soil cores is described. The technique was used to assess the effect of infiltrating gypsum (CaS0,.2H20) solution, sodium chloride solution, and distilled water on the conductivity of a sodic heavy clay at matric potentials between -0.5 and -8 kPa. Percolation of one liquid-filled pore volume of gypsum solution (concentration 29 m.e./l.) induced an approximately fourfold increase in hydraulic conductivity, relative to the conductivity with distilled water. This enhanced conductivity did not change when the permeating solution was changed to sodium chloride solution (30 m.e./l.). But when distilled water was substituted for either the gypsum or sodium chloride solutions, the conductivity declined rapidly, but not to its pretreatment value. Possible mechanisms responsible for the conductivity changes are discussed.

The effect of electrolyte solutions on hydrodynamic and backmixing characteristics in bubble columnns

Gas holdup and axial heat dispersion coefficient measurements in the presence of an electrolyte solution are presented. The experiments were carried ou

Effects of Electrolyte and Non-Electrolyte Solutions on the Tropic Responses ofAvenaColeoptiles

Solutions of mannitol and carbowax 1540 reduced the geotropic response of Avena sativa coleoptiles to at least the same extent as a potassium chloride solution of equal osmotic poten tial. Similar results were obtained with the phototropic response. The magnitude of these decreases increased almost linearly with the osmotic concentration of the solutions over the range 0-025-0-45 J cm 3. In contrast, the geotropic and phototropic responses were scarcely affected by exposing the coleoptiles to solutions of glycerol. The absence of an effect with glycerol is probably due to the penetration of the coleoptile cells by this solute. The similar or greater reduction in tropic curvature brought about by mannitol and carbowax 1540 solutions, as compared with a potassium chloride solution of equal osmotic potential, makes untenable a previous suggestion attributing the inhibitory effects of electrolyte solutions to a shunting of the electro-potential differences on the plant surface.

A model representing a physiological role of CO2 at the cell membrane.

A model is presented suggesting the interaction of CO(2) and bicarbonate on lipids of the cell membrane. The interfacial tensions between water and oil (benzene) phases were measured using the stalagmometer and the sessile drop methods. Effects of electrolyte solutions and of CO(2) on molecular arrangement at the interface were calculated. Chloride solutions against oleic acid in benzene produced little decrease in interfacial tension from that measured for pure water against the oil phase. Presence or absence of CO(2) caused no change in interfacial tension of water or chloride solutions against the oil phase. Bicarbonate salts in the absence of CO(2) caused marked decreases in interfacial tension from that measured for water or chloride solutions. Concomitant with this decrease in interfacial tension were an increase in hydration of the interface and changes in molecular spacings of the lipid. This hydration may be considered as reflecting a more ionic-permeable cell membrane. The addition of CO(2) to the bicarbonates caused an increase in interfacial tension of the model, approaching that of the chlorides, with decreased hydration of the interface. Viewed as occurring at the cell membrane this would make the lipid more continuous and decrease the ease of ionic penetration. In this way the action of bicarbonates and CO(2) at the interface suggests an explanation of the action of CO(2) on the cell.