Presence Of Various Electrolytes Research Articles

Li Salt Assisted Highly Flexible Carbonaceous Ni3N@polyimide Electrode for an Efficient Asymmetric Supercapacitor.

This work used a highly flexible, sustainable polyimide tape as a substrate to deposit ductile-natured carbonaceous Ni3N (C/Ni3N@polyimide) material for supercapacitor application. C/Ni3N was prepared using a co-sputtering technique, and this method also provided better adhesion of the electrode material over the substrate, which is helpful in improving bending performance. The ductile behavior of the sputter-grown electrode and the high flexibility of the polyimide tape provide ultimate flexibility to the C/Ni3N@polyimide-based supercapacitor. To achieve optimum electrochemical performance, a series of electrochemical tests were done in the presence of various electrolytes. Further, a flexible asymmetric supercapacitor (NC-FSC) (C/Ni3N//carbon@polyimide) was assembled by using C/Ni3N as a cathode and a carbon thin film as an anode, separated by a GF/C-glass microfiber soaked in optimized 1 M Li2SO4 aqueous electrolyte. The NC-FSC offers a capacitance of 324 mF cm-2 with a high areal energy density of 115.26 μWh cm-2 and a power density of 811 μW cm-2, with ideal bending performance.

Polymeric ferrite composites as versatile adsorbents for enhanced reactive blue dye removal: a promising solution for treating textile wastewater

ABSTRACT Water contamination caused by the increasing industry and urbanisation is one of the most significant environmental problems that entire planet is facing. Various polymeric ferrite composites synthesised in the current study were employed to remove the synthetic reactive dye blue-248 from wastewater. The polymeric ferrite composites were characterised using scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transmission infrared spectroscopy (FTIR) to observe the surface morphology, crystallinity and chemical structure of as-prepared composites. The optimum removal of dye using Ni-CoFe2O4/Chitosan, Zn-NiFe2O4/Starch, CoNiZnFe2O4/Polyaniline, Ni doped CrZnFe2O4/Alginate, Cr doped ZnCoFe2O4/PVA was at (i) pH 2 (32.34 mg/g), 3 (30.31 mgg−1), 3 (21.05 mgg−1), 3 (25.69 mgg−1) and 4 (38.61 mgg−1), (ii) optimum dose (0.03 mg/g) 32.40, 30.27, 21.91, 25.98 and 39.2 mg/g, (iii) Contact time (6090 min) 46.898, 37.70, 43.318, 29.356 and 34.12 mg/g, (iv) Initial dye concentration 32.24 mgg1, 25.79 mgg−1 (120 mg/L), 35.85 mgg−1, 28.37 mgg−1 and 40.37 mgg−1 (150 mg/L) and (v) temperature (65°C) 29.67, 27.08, 21.66, 23.60 and 41.40 mg/g, respectively. Different equilibrium, kinetic and thermodynamic models were used to check the nature of sorption, reaction rate/order of reaction and feasibility of reaction, respectively. The effect of presence of various electrolytes, different metals and surfactants in wastewater were also studied. For dye removal on a large scale, the effects of bed height (1–3 cm), flow rate (1.8–5.4) and initial dye concentration (50–90 ppm) were examined in column study. Different eluents were used for the desorption study of reactive dyes to check the reusability of process.

An elaborate investigation on the transition of rod-like micelle of cetyltrimethylammonium p-toluenesulfonate in presence of different additives

Abstract The noticeable change in self-aggregation nature (rod-like micelle) of cetyl trimethylammonium p-toluene sulfonate (CTAT) in presence of various electrolytes and non-electrolytes was probed using tensiometry, conductometry, isothermal titration calorimetry and fluorimetry. The impact of electrolytes and non-electrolytes on the critical micelle concentration (CMC) of the surfactant was found to be opposite of each other. The non-electrolytes having lower dielectric constants than water increased the repulsion between the surfactant head groups, thereby increasing the CMC. Less negative value of ΔG0m with increase in solvent concentration indicated delayed process of micellization. On the contrary, electrolytes decreased the CMC by a large extent due to suppression of the repulsion between the charged head groups by supplying more counter ions from the salts. The aggregation number of CTAT solution in presence of electrolytes increased with increase in salt concentration but decreased in presence of non-electrolytes, with increase of its concentration. The packing parameter value indicated the transition towards spherical shape with increase in concentration of non-electrolytes and increase in more non-spherical shape with increase in concentration of electrolytes for rod-like micelles of CTAT.

Interfacial electrochemical properties of natural Moroccan Ghassoul (stevensite) clay in aqueous suspension

A raw Moroccan clay locally named “Ghassoul” (Gh) was characterized using several techniques such as Fourier Transform Infrared Spectroscopy (FTIR), X-Ray Diffraction (XRD), Brunauer, Emmett and Teller method (BET), Scanning Electron Microscopy (SEM) and simultaneous Thermo-Gravimetric and Differential Thermal Analysis (TGA/DTA). These techniques indicate that the Gh consists essentially of steveniste, calcite, dolomite and quartz. The study of the interfacial electrochemical properties of Gh in different solutions of electrolyte salts (NaCl, CsCl, NaF, NaBr and LiCl) was carried out using the potentiometric and conductometric titrations It was shown that the Gh particles were stable in aqueous phase within the pH range (3–12) and the point of zero charge (PZC) was located at pH = 10.7. The adsorption sequence, carried out at various ionic strengths, showed that the adsorption mechanism onto the Gh particles is both electrostatic and specific at pH below the pHpzc, while at a pH range greater than the pHpzc the mechanism is electrostatic in nature. The total number of surface sites, determined using the graphical extrapolation method, was 11OH/nm2. Ionization constants (pKint+ and pKint−) in the presence of various electrolytes have also been determined and their values are 10.08 and 12.38, respectively.

Micellization properties of antihistaminic drug diphenhydramine.HCl in aqueous electrolytic solution: Conductometric and spectroscopic studies

The empathetic knowledge about the drug-electrolyte interactions is imperative in understanding the pharmacology and pharmacokinetics of drug. Therefore in the present paper, the effect of aqueous electrolytic solutions on the micellization behavior of an antihistaminic drug diphenhydramine.HCl (DPH) has been extensively examined through conductometric, fluorometric and spectrophotometric studies. The effect of various electrolytes occurring in the body fluid on self-association behavior of DPH was evaluated in terms of critical micelle concentration (CMC) obtained by conductivity and spectroscopic data over the temperature range (298.15–313.15) K with the regular interval of 5 K. The so obtained CMC data is used to calculate standard Gibbs free energy change of micellization (ΔGmo), entropy change of micellization (ΔGmo), and enthalpy change of micellization (ΔHmo), for the aforesaid drug in the presence of various electrolytes. The standard thermodynamic parameters of micellization were used to examine various solute-solvent interactions existing in drug-electrolyte-water system under discussion. Various thermodynamic parameters viz. ΔGmo, ΔHmo, and ΔGmo found to support the fact that electrolytes favor the association behavior of the DPH, which is further validated by pseudo-phase model.

Conductometric and spectrophotometric studies of self-aggregation behavior of streptomycin sulphate in aqueous solution: Effect of electrolytes

The effect of some electrolytes present in body fluid on micellar properties of the antibiotic drug streptomycin sulphate has been determined conductometrically over the temperature range 298.15–313.15 K with an interval of 5 K. The outcomes obtained from this study are further supported by fluorescence and UV measurements. The observed critical micelle concentration (CMC) data have been used to calculate standard thermodynamic parameters of micellization like free energy of micellization (ΔGmo), entropy change of micellization (ΔSmo), and enthalpy change of micellization (ΔHmo) for the aqueous solution of surface active drug streptomycin in the presence of various electrolytes. These parameters of micellization have been explored in terms of hydrophobic and hydrophilic interactions present in water–drug–electrolyte ternary system. The ΔGmo, ΔHmo, and ΔSmo values indicate that the electrolytes favor the aggregation behavior of the drug and process of micellization is well accommodated by enthalpy and entropy determinants. The interionic interactions have been elucidated by applying the model of pseudo phase separation.

Effect of electrolytes on stable permeation of submicron silica particles through microfiltration membranes

The permeation behaviors of submicron silica particles that were smaller than the pore size of microfiltration membranes were studied in the presence of various electrolytes with changing the concentrations. Stable permeations that maintained the initial fluxes and high permeation ratios were demonstrated when the monodisperse submicron silica particles containing 0.1 mM sodium hydroxide (NaOH) as electrolytes were used as the feed. Under these conditions, the zeta potentials of the silica particles were the most negative, and, accordingly, the electro-repulsive effect was strengthened to avoid deposition onto the surface as well as clogging inside the pores of the membranes. A stable permeation in the presence of 0.1 mM NaOH was also demonstrated for polydisperse submicron silica particles. These results are helpful to develop a novel particle classification technique using the microfiltration membranes that we have been studying.

Role of the triple solute/ion/water interactions on the saccharide hydration: A volumetric approach

The aim of this study is to further the understanding of the mechanisms that govern the hydration behavior of neutral solutes, with respect to the ions' properties that are present in a solution. For that, a systematic volumetric study of saccharides (xylose, glucose and sucrose), in the presence of various electrolytes (LiCl, NaCl, KCl, Na2SO4, K2SO4, CaCl2, MgCl2, MgSO4) has been carried out with density measurements at 298.15 K. From this data, the standard transfer molar volume of the saccharide ΔVϕ,S0, which characterizes the hydration state of the solute, has been determined.Positive and increasing values of ΔVϕ,S0 with increasing electrolyte concentrations were obtained. This indicated the dehydration of the saccharide in the presence of the electrolyte, due to the predominance of saccharide/cation interactions.Concerning the influence of the cation, it was shown that saccharides are more dehydrated in the presence of divalent cations than in the presence of monovalent ones. This is because the interactions are stronger between saccharides and divalent cations, in comparison to those with monovalent cations. For a specific cation valence and molality, regardless of the anion, saccharide dehydration increases according to the following sequences: Li+< Na+< K+ and Mg2+< Ca2+. These saccharide dehydration sequences have been explained by the Gibbs free energy of hydration of the cations, reflecting the cation/water interactions. For a specific cation valence, it was concluded that decreasing cation/water interactions induce the increase of saccharide dehydration.Concerning the influence of the anion, it was also observed that saccharides are more dehydrated in the presence of divalent anions than in the presence of monovalent ones. It was stated that saccharide/cation interactions are modulated by the nature of the anion. The anion impact was again attributed to its capacity to interact with water molecules. It was pointed out that anions with increasing values of Gibbs free energy of hydration cause an increase in saccharide/cation interactions or a decrease in saccharide/anion interactions. Therefore, saccharide dehydration increases.

Synthetic functionalized terpolymeric resin for the removal of hazardous metal ions: synthesis, characterization and batch separation analysis

An effectual functionalized synthetic resin involving anthranilic acid/4-nitroaniline/formaldehyde was synthesized for the detoxification of hazardous metal ions. The resin was characterized by Fourier transform infrared, 1H, and 13C nuclear magnetic resonance spectroscopy, and its morphology was established through scanning electron microscope and X-ray diffraction. The resin was analyzed by thermogravimetric analysis to assess the thermal stability, in which the resin could be used in high temperature aqueous solutions for the elimination of harmful metal ions. The ion-exchange property of the resin was evaluated by batch technique for specific metal ions viz. Fe3+, Co2+, Ni2+, Cu2+, Zn2+, and Pb2+. The study was extended to three variations such as effect of metal ion uptake in the presence of various electrolytes in different concentrations, effect of pH, and effect of contact time. The outcome proved that the resin can be used as a strong cation-exchanger to remove various metal ions from the solutions. The resin could be regenerated and reused with quantitative recovery of metal ions for few cycles. On comparison with the earlier reported resins, the synthesized resin has found excellent capability of metal ion recovery. The resin possesses an utmost ion-exchange capacity, which is in good harmony with isotherm models and kinetics. Copyright © 2015 John Wiley & Sons, Ltd.

Cloud Point and Liquid-Liquid Equilibrium Behavior of Thermosensitive Polymer L61 and Salt Aqueous Two-Phase System.

The cloud point of thermosensitive triblock polymer L61, poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO), was determined in the presence of various electrolytes (K2HPO4, (NH4)3C6H5O7, and K3C6H5O7). The cloud point of L61 was lowered by the addition of electrolytes, and the cloud point of L61 decreased linearly with increasing electrolyte concentration. The efficacy of electrolytes on reducing cloud point followed the order: K3C6H5O7 > (NH4)3C6H5O7 > K2HPO4. With the increase in salt concentration, aqueous two-phase systems exhibited a phase inversion. In addition, increasing the temperature reduced the concentration of salt needed that could promote phase inversion. The phase diagrams and liquid-liquid equilibrium data of the L61-K2HPO4/(NH4)3C6H5O7/K3C6H5O7 aqueous two-phase systems (before the phase inversion but also after phase inversion) were determined at T = (25, 30, and 35) °C. Phase diagrams of aqueous two-phase systems were fitted to a four-parameter empirical nonlinear expression. Moreover, the slopes of the tie-lines and the area of two-phase region in the diagram have a tendency to rise with increasing temperature. The capacity of different salts to induce aqueous two-phase system formation was the same order as the ability of salts to reduce the cloud point.

Surface potential of hematite particles in high concentration electrolytes: Electroacoustic measurements and suspension stability

The behavior of hematite particles and their surface charge in the presence of various electrolytes ranging from 10−3 to 10molL−1 has been investigated. Zeta potential measurements were performed using an electroacoustic device, and results showed that the nature of the alkaline cation in solution (Li+, Na+, K+, Cs+ or tetramethylammonium) leads to the presence or absence of a charge neutralization for higher concentrations. This behavior follows the indirect Hofmeister series (lithium has the strongest effect) and may be attributed to the hard or soft nature of the cation. This effect was also shown by experiments with various anions (OH−, Cl−, Br−, NO3−, ClO4−). Calculations using the classical DLVO theory predicted stability in agreement with the observed macroscopic behavior of the hematite suspensions, and most notably the rate and degree of sedimentation.

Effect of surfactant on electrokinetic properties of polyindole/TiO2-conducting nanocomposites in aqueous and nonaqueous media

In this study, polyindole (PIN)/TiO2 nanocomposites were synthesized with and without the presence of sodium dodecylsulfate, anionic surfactant, with two different PIN contents. The synthesized materials were subjected to various characterizations namely: particle size, apparent density, conductivity, dielectric constants, magnetic susceptibility, elemental analysis, Fourier transform infrared spectroscopy spectroscopy, thermogravimetric analysis, X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. Characterization results revealed the successful preparations of PIN/TiO2 hybrid nanocomposites. Electrokinetic properties of all the materials were determined by zeta (ζ)-potential measurements in aqueous and nonqueous media. Effects of pH, temperature, presence of various electrolytes, and surfactants on electrokinetic properties of the materials were examined.

Batch separation studies for the removal of heavy metal ions using a chelating terpolymer: Synthesis, characterization and isotherm models

Chelating terpolymer resin was synthesized from anthranilic acid and 2-amino pyridine with formaldehyde to remove the heavy metal ions present in the solutions. The synthesized terpolymer resin was characterized by spectral techniques such as FTIR, NMR (1H and 13C) and elemental analysis to elucidate the structure of the resin. The physico-chemical parameters have also been evaluated for the terpolymer resin. The surface morphology of the terpolymer resin without the metal ion uptake and with the incorporation of the metal ion was examined by scanning electron microscopy. The chelation ion-exchange property of the terpolymer resin was evaluated by batch equilibrium method for specific metal ions viz. Fe3+, Co2+, Ni2+, Cu2+, Zn2+, and Pb2+. The study was extended to three variations such as evaluation of metal ion uptake in presence of various electrolytes in different concentrations, evaluation of the distribution of metal ion uptake at different pH ranges and evaluation of the rate of metal ion uptake at different time intervals. The adsorption isotherm was evaluated by means of Langmuir and Freundlich isotherm models. The order of the kinetics was also determined and the resin follows first order kinetics which shows that physisorption may be involved in the ion-exchange process. From the results, it was observed that the terpolymer resin acts as an excellent cation-exchanger. Compared to the commercially available phenolic and polystyrene resins, the synthesized terpolymer resin showed an excellent ion-exchange capacity with the selected metal ions.

Electrolyte effect on the aggregation behavior of 1-butyl-3-methylimidazolium dodecylsulfate in aqueous solution

Effect of three inorganic electrolytes (LiCl, NaCl, and MgCl2) and four organic electrolytes, viz. tetraalkylammonium bromides ((CH3)4NBr, (C2H5)4NBr, (C3H7)4NBr, and (C4H9)4NBr) on the aggregation behavior of the anionic halogen-free surface active ionic liquid, 1-butyl-3-methylimidazolium dodecylsulfate ([C4mim][C12SO4]), in aqueous solution was studied by surface tension, steady-state fluorescence quenching, and dynamic light scattering measurements. The results show that all the electrolytes investigated have a salting-out effect, which promotes aggregate formation of [C4mim][C12SO4]. The stronger hydrophobicity of organic electrolytes is crucial for the superior influence on the surface activity of [C4mim][C12SO4]. However, the stabilization energy results obtained by quantum chemical calculations prove that although the promoting effect of organic cations (tetraalkylammonium cations) on the micellization process of [C4mim][C12SO4] is powerful, they mainly act as counterions. For a given electrolyte (i.e., NaCl), critical micelle concentration of [C4mim][C12SO4] decreases with increasing electrolyte concentration. The average aggregation number and aggregate size of [C4mim][C12SO4] were shown to change slightly in the presence of various electrolytes, except for MgCl2. Anyway, hydrophobicity together with bulkiness and hydration ability of cations of the added electrolytes are suggested to play important roles in modifying the aggregation behavior of [C4mim][C12SO4] in aqueous solution.

Investigation of electrokinetic and electrorheological properties of polyindole prepared in the presence of a surfactant

In this study, synthesis of polyindole (PIN) was carried out without and with the presence of a sodium dodecyl sulfate (SDS) surfactant (SPIN), using FeCl3 as an oxidizing agent. The synthesized materials were subjected to various characterizations techniques namely: particle size, magnetic susceptibility, elemental analysis, density, conductivity, dielectric constant, FTIR, 1H NMR, TGA, XRD, and SEM. Characterization results revealed the successful preparation of the homopolymers of PIN and SPIN. Zeta (ζ)-potentials of the samples were measured in aqueous and non-aqueous (silicone oil, SO) media. Electrokinetic properties of PIN and SPIN in aqueous media were determined by ζ-potential measurements in the presence of various electrolytes (NaCl, BaCl2, AlCl3, Na2SO4) and surfactants (cetyltrimethyl ammonium bromide, SDS, and Triton X-100). Besides, the effect of pH onto ζ-potentials of the materials was also examined. The suspensions prepared in SO were subjected to external electric field strength and their electrorheological (ER) properties were investigated. Then the effects of shear rate, frequency, and temperature onto ER activities of the suspensions were examined. Further, creep and creep–recovery tests were applied to the PIN/SO and SPIN/SO suspension systems and reversible non-linear viscoelastic deformations observed under applied electric field.

The sorption of cationic dyes onto kaolin: Kinetic, isotherm and thermodynamic studies

This study investigated the potential use of a low-cost inorganic powder (Persian Kaolin) for removal of Basic Yellow 28 (BY28), Methylene Blue (MB) and Malachite Green (MG) from aqueous solution. Kaolin was characterized via a laser particle size analyzer (PSA), scanning electron microscope (SEM), X-ray diffraction (XRD) and X-ray fluorescence (XRF) techniques. The effect of adsorbent dosage, dye concentration, initial pH and the presence of various electrolytes was studied. The isotherm data of dyes were correlated reasonably well by the Langmuir adsorption isotherm. The values of the adsorption capacity of kaolin towards the cationic dyes ranged from 16 mg/g to 52 mg/g, being probably dependent on the geometry of the dye molecules. The resulting degrees of dye removal were 65–99% for initial dye concentration of 10 mg/L and for kaolin loadings of 0.8–2.5 g/L. It was found that the adsorption of dyes on kaolin followed a pseudo-second order equation. The recovery and reuse of kaolin for a second and third time have also been studied. The thermodynamic studies showed that the dye adsorption onto kaolin is a spontaneous, endothermic and a physical reaction.

Effect of electrolytes on the slow aggregation of TiO2 nanocrystals

We studied the slow aggregation of dilute TiO2 hydrosols containing narrow fractions of nanocrystals separated from polydisperse sol by the stepwise coagulation with portions of HCl. It is shown that the kinetics of this process and the structure of formed aggregates greatly depend on the ionic strength and the pH of a medium. It is suggested that, in the presence of various electrolytes, the aggregation proceeds by an identical mechanism. In this case, highly ordered aggregates are formed in which there are thin layers of medium between TiO2 nanocrystals.

Effects of inorganic electrolytes on zeta potentials of ceramic microfiltration membranes

The characterization of surface electrical properties of membrane materials is critical for understanding and predicting filtration performances of membranes. In this paper, electrical properties of alumina-based ceramic microfiltration membrane were studied. Zeta potential of the membranes itself is determined using electro-osmosis measurements in the presence of various electrolytes, including NaCl, NH 4Cl, CaCl 2, FeCl 2, AlCl 3, Na 2SO 4, Na 2S, Na 3PO 4, FeSO 4 and Al 2(SO 4) 3, which are commonly encountered in inorganic salt industry. The zeta potential is obtained over a wide range of pH values (2–12) at ionic strengths of 0.01 M. The zeta potential decreases with increase of ionic strength in the NaCl solution and isoelectric point (IEP) shows little dependence on the ionic strength indicating the absence of a specific adsorption of Cl − and Na + ions. The shifting of the IEP of the membrane to a higher pH value in FeCl 2, CaCl 2 and AlCl 3 solutions shows specific adsorption of the cations, and specific adsorption of the S 2−, S O 4 2 − , P O 4 3 − ions shifts the IEP to a lower pH value. The zeta potential in FeSO 4 and Al 2(SO 4) 3 solutions were very low, indicating a decrease of charge density on the membrane surface due to the complex co-adsorption of the cations and the anions on the membrane surface.

Development of a frequency-dependent-type apex locator with automatic compensation.

Among apex locators, the frequency dependent type is more accurate and convenient to use than others. However, the accuracy of the apex locator is still influenced by the presence of various electrolytes used in root canal treatments. In this study, we developed a frequency-dependent electronic apex locator minimizing the influence of electrolytes on the measurement of root canal lengths. It was confirmed that the two frequencies of 0.5 and 10 kHz are better than the conventional ones of 0.4 and 8 kHz. The impedance ratio of the two different frequencies represents the position of the file in root canal, and the voltage difference of the two frequencies represents the status of the fluid in the root canal. As a result of compensation using the voltage differences of the two frequencies, the errors decreased significantly on average from +0.54 mm to +0.18 mm in H2O2 solution (p < 0.01), and from -0.33 mm to -0.01 mm in NaOCl solution (p < 0.01) in the tooth model experiments.

Precipitation of a Water-Soluble ABC Triblock Methacrylic Polyampholyte: Effects of Time, pH, Polymer Concentration, Salt Type and Concentration, and Presence of a Protein

The solution behavior of a low molecular weight ABC triblock methacrylic polyampholyte with the structure (dimethylaminoethyl methacrylate)8−(methyl methacrylate)12−(methacrylic acid)16 was investigated by turbidimetry. The variation of the optical density at 420 nm of dilute polyampholyte solutions with time, pH, polymer concentration, salt type and concentration, and presence of a protein was explored. Polyampholyte precipitation was fast and occurred around the isoelectric pH. The size of the aggregates increased with increasing salt concentration and was independent of polyampholyte concentration. High salt concentrations suppressed polyampholyte precipitation. The precipitation in the presence of various electrolytes at a concentration of 0.2 M was insensitive to the anion type for a series of potassium halides and also to the divalent sulfate anion, but was greatly increased by the divalent calcium cation and was completely suppressed by the anionic surfactant sodium dodecyl sulfate. The polyampholyte formed insoluble complexes with a basic protein, chicken egg lysozyme, in the pH region between the isoelectric points of the two reactants. The results of this study will be useful for designing the extraction of solutes, such as heavy metals and proteins, via polyampholyte electrostatic complexation; moreover, they will facilitate the development of efficient strategies for polyampholyte recovery and recycling.