Strong Electrolytes Research Articles

Stimulation of Plant Growth with an Aqueous Solution Activated by Glow Discharge Plasma

Abstract—This paper presents the results on the application of low-concentration aqueous solutions of strong electrolytes activated by glow discharge plasma for plant growth stimulation. We provide experimental evidence that these solutions can be used as an effective regulator of plant growth.

Microfluidic Mixer with Automated Electrode Switching for Sensing Applications

An electronic tongue (e-tongue) is a multisensory system usually applied to complex liquid media that uses computational/statistical tools to group information generated by sensing units into recognition patterns, which allow the identification/distinction of samples. Different types of e-tongues have been previously reported, including microfluidic devices. In this context, the integration of passive mixers inside microchannels is of great interest for the study of suppression/enhancement of sensorial/chemical effects in the pharmaceutical, food, and beverage industries. In this study, we present developments using a stereolithography technique to fabricate microfluidic devices using 3D-printed molds for elastomers exploring the staggered herringbone passive mixer geometry. The fabricated devices (microchannels plus mixer) are then integrated into an e-tongue system composed of four sensing units assembled on a single printed circuit board (PCB). Gold-plated electrodes are designed as an integral part of the PCB electronic circuitry for a highly automated platform by enabling faster analysis and increasing the potential for future use in commercial applications. Following previous work, the e-tongue sensing units are built functionalizing gold electrodes with layer-by-layer (LbL) films. Our results show that the system is capable of (i) covering basic tastes below the human gustative perception and (ii) distinguishing different suppression effects coming from the mixture of both strong and weak electrolytes. This setup allows for triplicate measurements in 12 electrodes, which represents four complete sensing units, by automatically switching all electrodes without any physical interaction with the sensor. The result is a fast and reliable data acquisition system, which comprises a suitable solution for monitoring, sequential measurements, and database formation, being less susceptible to human errors.

CONSTANT OF ELECTROLYTIC DISSOCIATION OF LITHIUM, SODIUM AND POTASSIUM SULPHATES IN AQUEOUS ETHANOL SOLUTIONS

Constants of electrolytic dissociation of the lithium, sodium and potassium sulphates in aqueous ethanol solutions at 25 °C were determined by conductometric method. Li2SO4, Na2SO4, K2SO4 were shown to decrease their ability to dissociation. It is generally accepted that the degree of electrolytic dissociation of electrolytes in a solution depends on the dielectric constant of the solvent. Water and ethanol differ greatly in their dielectric constant. For this reason, it is possible to prepare the solvent with different dielectric permittivity by changing the alcohol content in a mixture with water, thus, influencing the equilibrium state of the salt in solution. Therefore, in water-ethanol solutions with an increase in the alcohol content, sulfates of lithium, sodium and potassium should exhibit the properties of a weak electrolyte. In this case, the dependence of the molar conductivity on the concentration of sulfates of lithium, sodium and potassium in water-ethanol solutions will have a different appearance. Indeed, with an increase in the alcohol content in aqueous ethanol solutions, the molar conductivity decreases due to a decrease in the degree of electrolytic dissociation. With a decrease in the salt concentration in the solution, the molar electrical conductivity increases, approaching λ0, for both water and water-alcohol solutions. As it follows from the obtained data, the dependence of λ on the total concentrations of Li2SO4, Na2SO4, K2SO4) for the water solution with a high correlation coefficient is transformed into a straight line in the coordinates of the Kolraush equation since the sulfates of lithium, sodium and potassium act as strong electrolytes in the aqueous medium. For water-ethanol solutions, a high correlation coefficient in the coordinates of the equation 4λ3· C0(M2SO4)2 = КDIS · λ03 - КDIS - λ02·λ is observed in the case of [C2H5OH]> 50% of the volume. This means that in these solutions lithium, sodium and potassium sulphates exhibit the properties of a weak electrolyte. When the alcohol content is from 10% to 40% by volume, sulfates of lithium, sodium and potassium are medium-strength electrolyte and, therefore, low correlation coefficients are characteristic of transformations in the coordinates of the equations Kohlrausch and 4λ3· C0(M2SO4)2 = КDIS · λ03 - КDIS - λ02·λ.

Generation of H+ and OH− ions in anion-exchange membrane/ampholyte-containing solution systems: A study using electrochemical impedance spectroscopy

Generation of H+ and OH− ions at anion-exchange membranes is a phenomenon, which substantially reduces the performance of a number of electromembrane processes, such as the wastewater treatment, fuel cell energy production and others. We show that the mechanisms of this phenomenon are different, when a Neosepta AMX anion-exchange membrane is bathed in a strong electrolyte solution (NaCl and KCl) or in an ampholyte solution (NaH2PO4, KH2PO4, KHT and KH2Cit). The H+ and OH− ions' generation in the case of strong electrolytes requires a voltage threshold (about 0.3 V of the corrected voltage not including ohmic contribution), which relates to a current close to the limiting current. The process occurs mainly through proton transfer reactions involving the membrane functional groups. In the case of ampholytes, this generation takes place without a threshold; this process is separated in space: the generation of H+ occurs at the depleted solution/membrane interface, that of OH− ions, at the membrane boundary with the enriched solution. Electrochemical impedance spectra (EIS) are used for the determination of the effective rate constants for the H+ and OH− ions’ generation. Their values are compared with the rate constants calculated from the acid dissociation constants (Ka).

On the role of hydrophobic interactions between chloramphenicol and bovine pancreatic trypsin: The effect of a strong electrolyte

We report the interaction between a well-known antibiotic chloramphenicol (Clp) and the protein, bovine pancreatic trypsin. Both steady-state and time-resolved measurements, along with binding constant measurements which varies inversely with temperature, emphasize the static quenching mechanism induced by the added Clp. Additionally, Isothermal Titration Calorimetry (ITC) and docking analyses conclusively substantiate the role of hydrophobic interactions as the primary mode of binding. The structural alteration of trypsin in presence of Clp was monitored by Circular Dichroism (CD) spectroscopy. Addition of strong electrolytes enhances the binding affinity of Clp with trypsin which also increases hydrophobic interaction, due to salting out effect.

Controlled synthesis of Bi2O2C4H2O4 hierarchical micro-spheres by solution-phase methods

This paper presents the results of the preparation of bismuth (III) oxofumarate (BiO)2C4H2O4 hierarchical micro-spheres from solutions of bismuth salts. Precipitation of (BiO)2C4H2O4 occurred from aqueous solutions of fumaric acid C4H4O4. The solubility of the obtained samples was studied in inorganic solvents. Strong electrolytes were used to show solubility over a wide pH range. Solubility in a weak electrolyte NH4OH was also considered. The phase composition of (BiO)2C4H2O4 in the samples was established by X-ray diffraction, thermogravimetric and chemical analyzes. Analysis of the size and morphology of the resulting particles was carried out by using methods of scanning electron microscopy and low-angle laser light scattering.

Graphene-MoS2 vertically anchored on an MXene-derived accordion-like TiO2/C skeleton: an ultrastable HER catalyst

An MXene-derived accordion-like TiO2/C substrate was fabricated for the first time and the as-fabricated rGO-MoS2/Acc-TiO2/C catalyst exhibited ultrahigh electrochemical stability in a strong acid electrolyte for the hydrogen evolution reaction.

Күштi электролиттердiң темiр топшасы иондарының комплекс түзу процесiнiң физика химиялық және термодинамикалық қасиеттерiне әсерi

Методом рН-метрии определены константы устойчивости комплексов ионовподгруппы железа Fe(II), Co(II), Ni(II) с органическими лигандами (дибутилдитиофосфатомнатрия, дибутилдитиофосфатом калия, дибутилдитиофосфата аммония) в интервалетемператур 298–318 К при разных ионных силах (I = 0.1–0.75 моль/л). На основаниитемпературной зависимости констант устойчивости определены термодинамические функциипроцессов образования комплексов ионов подгруппы железа с дибутилдитиофосфатамищелочных металлов и аммония.Изучено влияние сильного электролита нитрата натрия (NaNO 3 ) на изменениеэнтальпии процесса образования комплексов ионов подгруппы железа с фосфорсодержащимисобирателями. Изучено воздействие электролита NaNO 3 на физико-химические свойствакомплексов диалкилдитиофосфатов щелочных металлов и аммония с ионами подгруппыжелеза. Приведена схема образования связей металл–сера для дибутилдитиофосфат-иона,обладающего высокой реакционной способностью.

Concentration Dependencies of Diffusion Permeability of Anion-Exchange Membranes in Sodium Hydrogen Carbonate, Monosodium Phosphate, and Potassium Hydrogen Tartrate Solutions.

The concentration dependencies of diffusion permeability of homogeneous (AMX-Sb and AX) and heterogeneous (MA-41 and FTAM-EDI) anion-exchange membranes (AEMs) is obtained in solutions of ampholytes (sodium bicarbonate, NaHCO3; monosodium phosphate, NaH2PO4; and potassium hydrogen tartrate, KHT) and a strong electrolyte (sodium chloride, NaCl). It is established that the diffusion permeability of AEMs increases with dilution of the ampholyte solutions, while it decreases in the case of the strong electrolyte solution. The factors causing the unusual form of concentration dependencies of AEMs in the ampholyte solutions are considered: (1) the enrichment of the internal AEM solution with multiply charged counterions and (2) the increase in the pore size of AEMs with dilution of the external solution. The enrichment of the internal solution of AEMs with multiply charged counterions is caused by the Donnan exclusion of protons, which are the products of protolysis reactions. The increase in the pore size is conditioned by the stretching of the elastic polymer matrix due to the penetration of strongly hydrated anions of carbonic, phosphoric, and tartaric acids into the AEMs.

Neutralization Dialysis for Phenylalanine and Mineral Salt Separation. Simple Theory and Experiment.

A simple non-steady state mathematical model is proposed for the process of purification of an amino acid solution from mineral salts by the method of neutralization dialysis (ND), carried out in a circulating hydrodynamic mode. The model takes into account the characteristics of membranes (thickness, exchange capacity and electric conductivity) and solution (concentration and components nature) as well as the solution flow rate in dialyzer compartments. In contrast to the known models, the new model considers a local change in the ion concentration in membranes and the adjacent diffusion layers. In addition, the model takes into consideration the ability of the amino acid to enter the protonation/deprotonation reactions. A comparison of the results of simulations with experimental data allows us to conclude that the model adequately describes the ND of a strong electrolyte (NaCl) and amino acid (phenylalanine) mixture solutions in the case where the diffusion ability of amino acids in membranes is much less, than mineral salts. An example shows the application of the model to predict the fluxes of salt ions through ion exchange membranes as well as pH of the desalination solution at a higher than in experiments flow rate of solutions in ND dialyzer compartments.

Back Cover: Inverting the Triiodide Formation Reaction by the Synergy between Strong Electrolyte Solvation and Cathode Adsorption for Lithium–Oxygen Batteries (Angew. Chem. Int. Ed. 51/2019)

Back Cover: Inverting the Triiodide Formation Reaction by the Synergy between Strong Electrolyte Solvation and Cathode Adsorption for Lithium–Oxygen Batteries (Angew. Chem. Int. Ed. 51/2019)

Inverting the Triiodide Formation Reaction by the Synergy between Strong Electrolyte Solvation and Cathode Adsorption for Lithium–Oxygen Batteries

AbstractAn exceptionally strong solvation effect of dimethyl sulfoxide (DMSO) on I2 is identified by the largest shift observed so far of the I2 Raman peak with respect to I2 vapor and by elongated I−I bond lengths in first‐principles molecular‐dynamics simulations. This effect together with strong binding by an RuO2 surface to I2 is found to invert the direction of the reaction I−+I2⇌I3− to the left‐hand side. Inspired by this finding, we prepared a Li–O2 battery with the Li/DMSO+LiI/RuO2 structure. The synergic action of DMSO and RuO2 on I2 is found to suppress the shuttle effect of the redox mediator (RM) by anchoring I2 molecules, the oxidation product of the RM. Significantly enhanced stability is demonstrated over 100 cycles at charging voltage below 3.65 V.

Inverting the Triiodide Formation Reaction by the Synergy between Strong Electrolyte Solvation and Cathode Adsorption for Lithium-Oxygen Batteries.

An exceptionally strong solvation effect of dimethyl sulfoxide (DMSO) on I2 is identified by the largest shift observed so far of the I2 Raman peak with respect to I2 vapor and by elongated I-I bond lengths in first-principles molecular-dynamics simulations. This effect together with strong binding by an RuO2 surface to I2 is found to invert the direction of the reaction I- +I2 ⇌I3 - to the left-hand side. Inspired by this finding, we prepared a Li-O2 battery with the Li/DMSO+LiI/RuO2 structure. The synergic action of DMSO and RuO2 on I2 is found to suppress the shuttle effect of the redox mediator (RM) by anchoring I2 molecules, the oxidation product of the RM. Significantly enhanced stability is demonstrated over 100 cycles at charging voltage below 3.65 V.

Activation of aqueous solutions by high-frequency glow discharge plasma in water vapor to stimulate growth and control diseases of agricultural plants

The results of an experimental study of the activation of weak aqueous solutions of a strong electrolyte with a low-temperature glow discharge plasma are presented. A method for producing an activated aqueous solution based on 0.9 % NaCl solution in a glow discharge plasma at atmospheric pressure is presented. The main characteristics of the activated aqueous solution, including the Raman spectrum at a wavelength λ = 514,53 nm, are shown. The results of experiments on the test objects give an assessment of the effectiveness of the effect of the obtained activated aqueous solution on various crops. In particular, experimental confirmation of the possibility of using this activated solution as a plant growth regulator was obtained.

Effect of Iron Chloride on the Strength Behaviour of the Expansive Clay

From the fast few decades, several techniques were introduced inorder to modify the behaviour of expansive clays. The use of strong electrolytes like calcium chloride (CaCl2), aluminum trichloride (AlCl3) and iron chloride (FeCl3) were extensively used in various civil engineering applications. Expansive soils possesses alternate shrinkage and swelling with the removal and addition of water from it. Iron chloride was effectively used to alter the swelling and shrinkage and also improve the engineering behaviour of expansive clays. Therefore, in the current work an effort is made for study the influence of iron chloride (FeCl3) on the strength behaviour of the expansive soil. The outcomes from the laboratory investigation proved that the usage of iron chloride (FeCl3) produce reduction in swelling and improvement in the strength. It was found that 1% FeCl3 be the optimum for both the UCS and CBR. Hence, from the investigation it was showed that iron chloride is a valuable stabilizer to enhance the properties of black cotton soil and to create it apt for various applications of Civil Engineering.

Engineering a flexible and mechanically strong composite electrolyte for solid-state lithium batteries

Engineering a flexible and mechanically strong composite electrolyte for solid-state lithium batteries

TiC supported amorphous MnOx as highly efficient bifunctional electrocatalyst for corrosion resistant oxygen electrode of Zn-air batteries

Zn-air batteries (ZABs) represent promising candidates for the next generation energy conversion and storage systems based on their superior features to those of lithium-ion batteries, including high theoretical energy density, low cost, and high safety. However, their further development and application is severely lagged due to the lack of high efficient and durable bifunctional oxygen electrocatalysts. The widely applied carbon-based catalysts are thermodynamically instable during battery charging. Herein, TiC supported amorphous MnOx (a-MnOx/TiC) is reported for the first time as electrocatalyst for the corrosion resistant oxygen electrodes of ZABs. A-MnOx/TiC delivers a remarkable activity and stability toward both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) with a high half-wave potential (0.8 V) for ORR and a low potential (1.56 V) at 10 mA cm−2 for OER, which far outperforms the state of the art ORR catalyst (Pt/C) and OER catalyst (IrO2), as well as the Pt/C-IrO2 and a-MnOx/C bifunctional catalysts. The excellent bifunctional activity of a-MnOx/TiC can be attributed to the efficient synergistic effect between the active amorphous MnOx catalyst and the highly conductive and stable TiC support. More impressively, a-MnOx/TiC demonstrates an outstanding electrochemical stability in strong alkaline electrolyte under OER condition in contrast to the readily oxidized carbon-based a-MnOx/C catalysts. ZAB with a-MnOx/TiC delivers a greater discharge performance with a peak power density of 217.1 mW cm−2 than that of Pt/C-based ZAB, and a surpassing discharge and charge cycling performance and stability to ZABs with Pt/C-IrO2 and a-MnOx/C. Furthermore, a-MnOx/TiC can be applied for solid-state ZABs which exhibit excellent mechanical flexibility and cycle stability under their flat and bent states. The a-MnOx/TiC bifunctional electrocatalyst with extraordinarily high activity and electrochemical stability provides a promising approach for exploring corrosion resistant electrocatalysts for Zn-air batteries with high efficiency and long-term cycling stability.

Phase behavior of surfactant mixtures and the effect of alkyl chain and temperature on lyotropic liquid crystal

In order to study lyotropic liquid crystal (LLC) which have good stability to strong electrolytes, inorganic salts and pH, the mixtures of Polyoxyethylene-10-oleyl ether (Brij 97) with different Polyoxyethylene (20) sorbitol fatty acid ester (Tweens®) were studied. Firstly, the phase diagrams had been constructed for Brij 97/Tween 20/H2O (Tween 20 system), Brij 97/Tween 40/H2O (Tween 40 system), Brij 97/Tween 60/H2O (Tween 60 system) and Brij 97/Tween 80/H2O (Tween 80 system). It showed that the difference in the alkyl chain length and insaturation of Tweens® had significant effect on the lyotropic liquid crystal phase region size. Secondly, the system containing Tweens® had smaller viscous moduli (G”), elastic moduli (G') and larger lattice parameter (α) than the system without Tweens®, which indicated that the latter has higher stability than the former. It is worth noting that the sample (Brij 97/Tween 40/H2O = 52.5/10/37.5) appeared as a mixed phase of hexagonal phase (H1) and micellar cubic phase (I1) at 37 °C, while the other samples behaved as hexagonal phase. It should also be noted that with the increase in temperature, the rheological properties of sample (Brij 97/Tween 60/H2O = 0/55/45) showed changes from viscous dominated to elastic dominated to viscous dominated, which provided a basis for thermosensitive materials and drug carriers.

An equation for the isosbestic point wavelength in aqueous solutions of electrolytes

The existence of an isosbestic point in the OH bond vibration band of H2O molecules in solutions of strong electrolytes has been shown by many research groups but its physical meaning has been only recently read as the equilibrium point between two populations of water molecules where either water-ion or water-water interactions respectively prevail. Thus the isosbestic point provides useful information on the bulk displacement of water molecules in presence of solutes. Herein we show that the isosbestic point occurrence is correctly described by an equation describing the balance of the electrostatic forces. Furthermore, its wavelength is also related to the slope of the density vs. the solute concentration. These results support the view that the effect of the solute can be barely regulated within few hydration shells.

High-Strength, Self-Adhesive, and Strain-Sensitive Chitosan/Poly(acrylic acid) Double-Network Nanocomposite Hydrogels Fabricated by Salt-Soaking Strategy for Flexible Sensors.

As a promising functional material, hydrogels have attracted extensive attention, especially in flexible wearable sensor fields, but it remains a great challenge to facilely integrate excellent mechanical properties, self-adhesion, and strain sensitivity into a single hydrogel. In this work, we present high in strength, stretchable, conformable, and self-adhesive chitosan/poly(acrylic acid) double-network nanocomposite hydrogels for application in epidermal strain sensor via in situ polymerization of acrylic acid in chitosan acid aqueous solution with tannic acid-coated cellulose nanocrystal (TA@CNC) acting as nanofillers to reinforce tensile properties, followed by a soaking process in a saturated NaCl solution to cross-link chitosan chains. With addition of a small amount of TA@CNC, the double-network nanocomposite hydrogels became highly adhesive and mechanically compliant, which were critical factors for the development of conformable and resilient wearable epidermal sensors. The salt-soaking process was applied to cross-link chitosan chains by shielded electrostatic repulsions between positively charged amino groups, drastically enhancing the mechanical properties of the hydrogels. The obtained double-network nanocomposite hydrogels exhibited excellent tunable mechanical properties that could be conveniently tailored with fracture stress and fracture strain ranging from 0.39 to 1.2 MPa and 370 to 800%, respectively. Besides, the hydrogels could be tightly attached onto diverse substrates, including wood, glass, plastic, polytetrafluoroethylene, glass, metal, and skin, demonstrating high adhesion strength and compliant adhesion behavior. In addition, benefiting from the abundant free ions from strong electrolytes, the flexible hydrogel sensors demonstrated stable conductivity and strain sensitivity, which could monitor both large human motions and subtle motions. Furthermore, the antibacterial property originating from chitosan made the hydrogels suitable for wearable epidermal sensors. The facile soaking strategy proposed in this work would be promising in fabricating high-strength multifunctional conductive hydrogels used for wearable epidermal devices.