Aqueous Potassium Chloride Research Articles

Cation-Dependent Mixed Ionic-Electronic Transport in a Perylenediimide Small-Molecule Semiconductor.

A rapidly growing interest in organic bioelectronic applications has spurred the development of a wide variety of organic mixed ionic-electronic conductors. While these new mixed conductors have enabled the community to interface organic electronics with biological systems and efficiently transduce biological signals (ions) into electronic signals, the current materials selection does not offer sufficient selectivity towards specific ions of biological relevance without the use of auxiliary components such as ion-selective membranes. Here, we present the molecular design of an n-type (electron-transporting) perylene diimide semiconductor material decorated with pendant oligoether groups to facilitate interactions with cations such as Na+ and K+. Using the cyclic 15-crown-5 oligoether motif, we find that the resulting mixed conductor PDI-crown displays a strong dependence on the size of the electrolyte cation when tested in an organic electrochemical transistor configuration. In stark contrast to the low current response on the order of 1 μA observed with aqueous sodium chloride, a nearly 200-fold increase in current is observed with aqueous potassium chloride. We ascribe the high selectivity to extended molecular aggregation and therefore efficient charge transport in the presence of K+ due to a favourable sandwich-like structure between two adjacent 15-crown-5 motifs and the potassium ion.

Structural Study of Aqueous Electrolyte Solution by MeV Liquid Electron Scattering.

The impact of ions on water has long been a subject of great interest, as it is closely tied to the hydration structure, dynamics, and properties of electrolyte solutions. Over centuries of investigation, the influence of ions on water's structure remains highly debated. Prevailing techniques, such as neutron and X-ray scattering, primarily focus on the microscopic structure of salt solutions at very high concentrations, mostly above 1 mol/L. In this study, we measured the structure of aqueous potassium iodide (KI) and potassium chloride (KCl) solutions using MeV liquid electron scattering (MeV-LES) across a concentration range of 0.10 to 0.75 mol/L. The obtained results provide detailed insights into the variations in ion-oxygen and oxygen-oxygen correlations as a function of concentration. The observed structural differences between KI and KCl solutions are in line with the structure maker/breaker theory, which suggests that iodide ions exert a more pronounced effect than chloride ions on disrupting the water shell. This work demonstrates the potency of MeV-LES for investigating the atomic structure in liquids, augmenting the modern analytical toolbox.

Analysis of Viscometric and Conductometric Properties of l-Ascorbic Acid in Aqueous Potassium Chloride and Diammonium Hydrogen Phosphate

Analysis of Viscometric and Conductometric Properties of <scp>l</scp>-Ascorbic Acid in Aqueous Potassium Chloride and Diammonium Hydrogen Phosphate

Cation‐Dependent Mixed Ionic‐Electronic Transport in a Perylenediimide Small‐Molecule Semiconductor

A rapidly growing interest in organic bioelectronic applications has spurred the development of a wide variety of organic mixed ionic‐electronic conductors. While these new mixed conductors have enabled the community to interface organic electronics with biological systems and efficiently transduce biological signals (ions) into electronic signals, the current materials selection does not offer sufficient selectivity towards specific ions of biological relevance without the use of auxiliary components such as ion‐selective membranes. Here, we present the molecular design of an n‐type (electron‐transporting) perylene diimide semiconductor material decorated with pendant oligoether groups to facilitate interactions with cations such as Na+ and K+. Using the cyclic 15‐crown‐5 oligoether motif, we find that the resulting mixed conductor PDI‐crown displays a strong dependence on the size of the electrolyte cation when tested in an organic electrochemical transistor configuration. In stark contrast to the low current response on the order of 1 µA observed with aqueous sodium chloride, a nearly 200‐fold increase in current is observed with aqueous potassium chloride. We ascribe the high selectivity to extended molecular aggregation and therefore efficient charge transport in the presence of K+ due to a favourable sandwich‐like structure between two adjacent 15‐crown‐5 motifs and the potassium ion.

Monte Carlo simulation study of the structure of calcium and potassium chlorides ternary solutions

ABSTRACT Monte Carlo simulations were conducted on pure water and aqueous calciumand potassium chloride ternary solutions at different salts concentrations. To assess the local order within the solutions, the Monte Carlo simulations utilised the Madrid-2019 force field, usingtheTIP4P/2005 water model and scaled charges. The results demonstrate that as the salt concentrations increase, there is a notable decrease in the contribution of the structured tetrahedral arrangement of water molecules, favouring an unstructured configuration instead. The use of the nearest neighbour approach, provided unambiguous information regarding the radial and orientation characteristics of the unstructured configuration of water. Structures of the solvation shells around ions are also studied. The Monte Carlo simulations indicate that as the salt concentration increases, the hydration number around the cation decreases. This effect is likely due to the occasional substitution of some water molecules in the first hydration shell by chlorine ions.

Surface Acoustic Wave Resonator Chip Setup for the Elimination of Interfering Conductivity Responses.

A surface acoustic wave (SAW) resonator chip setup is presented that eliminates interfering signal responses caused by changes in the electrical environment of the surrounding media. When using a two-port resonator, applying electrically shielding layers between the interdigital transducers (IDTs) can be challenging due to the limited dimensions. Therefore, a layered setup consisting of an insulating polymer layer and a conductive gold layer was preferred. The SAW resonators were provided with polycarbonate housings, resulting in SAW resonator chips. This setup enables easy application of a wide range of coatings to the active part of the resonator surface, while ensuring subsequent electrical and fluidic integration of the resonator chips into a microfluidic array for measurements. The signal responses of uncoated SAW resonators and those with polymer coatings with and without a gold layer were tested with aqueous potassium chloride (KCl) solutions up to 3 mol/L, corresponding to conductivities up to 308 mS/cm. The use of a polymer coating at the thickness of the first Love mode resonance and a conductive gold layer completely reduced the electrical impact on the SAW resonator signal response, making small signals resulting from changes in viscosity and density of the KCl solutions visible.

Self-assembled monolayer of poly(o-phenylenediamine)/silver core-shell hybrid-based enzyme-free impedimetric glucose sensor for blood samples.

A core-shell hybrid of poly(o-phenylenediamine)/silver was prepared by a simple single-step process and self-assembled on a glassy carbon electrode to design an enzyme-free electrochemical glucose sensor. The working electrode was fabricated by self-assembling a dimethyl sulfoxide (DMSO) solution of the prepared hybrid on a glassy carbon electrode. The electrochemical properties of the fabricated electrode were analyzed by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) in an aqueous potassium chloride electrolyte containing the [Fe(CN)6]3-/4- redox couple. The electrochemical sensing responses towards varying concentrations of glucose were studied by CV and EIS in the same redox electrolyte medium. The poly(o-phenylenediamine)/silver core-shell hybrid-based sensor was found to show a reliable response in the EIS experiment over the CV experiment. By analyzing the EIS sensing responses, the experimental limit of detection was determined to be 10 μL of ∼80 mg per dL glucose solution in 25 mL of 1 (M) KCl electrolyte containing the 10-3 M [Fe(CN)6]3-/4- redox couple with a sensitivity of 298 Ω mg-1 dL cm-2. Excellent selectivity towards glucose was confirmed over various bioactive interfering biomolecules like ascorbic acid, dopamine, uric acid, lactose, fructose and sucrose. The glucose content in the human blood sample was verified by the designed sensor with almost 100% recovery.

Mechanically robust and thermally enhanced sand‐polyacrylamide‐2D nanofiller composite hydrogels for water shutoff applications

AbstractHerein, we report a facile preparation method for mechanically robust and thermally enhanced sand‐polyacrylamide (PAM)‐2D‐nanofillers composite hydrogels and their application in water shutoff. To prepare the sample, 4 wt% of aqueous PAM solution is mixed with organic cross‐linkers of hydroquinone (HQ) and hexamethylenetetramine (HMT) in a 1:1 weight ratio and aqueous potassium chloride (KCl) solution and with a specific amount of 2D‐nanofillers such as commercial graphene (CG) nanosheets or boron nitride nanoparticles (BN NPs). A specific amount of the above solution is added to sand, well mixed, and subsequently cured at 150°C for 8 h. The prepared composite hydrogels were characterized by Fourier‐transform infrared spectroscopy (FT‐IR) for chemical composition and X‐ray diffraction (XRD) for successful hydrogel coating onto the sand particles. Thermal stabilities of the samples have been evaluated by differential scanning calorimetry (DSC). Mechanical properties (storage modulus [G′]; loss modulus [G″]; gel strength (G′/G″); and damping factor [G″/G′]) of the samples were determined using dynamic mechanical analyses. The thermal stability of the samples has reached as high as 193.4°C, while the gel strength is found to be a maximum of 16.2. The water swelling ratio for the composite hydrogel has reached a maximum of 1100% within 1 h.

Polymer gel amended sandy soil with enhanced water storage and extended release capabilities for sustainable desert agriculture

Herein, we report a facile preparation of super-hydrophilic sand by coating the sand particles with cross-linked polyacrylamide (PAM) hydrogels for enhanced water absorption and controlled water release aimed at desert agriculture. To prepare the sample, 4 wt% of aqueous PAM solution is mixed with organic cross-linkers of hydroquinone (HQ) and hexamethylenetetramine (HMT) in a 1:1 weight ratio and aqueous potassium chloride (KCl) solution. A specific amount of the above solution is added to the sand, well mixed, and subsequently cured at 150 °C for 8 h. The prepared super-hydrophilic sands were characterized by Fourier-transform infrared spectroscopy (FT-IR) for chemical composition and X-ray diffraction (XRD) for successful polymer coating onto the sand. The water storage for the samples was studied by absorption kinetics at various temperature conditions, and extended water release was studied by water desorption kinetics. The water swelling ratio for the super-hydrophilic sand has reached a maximum of 900% (9 times its weight) at 80 °C within 1 h. The desorption kinetics of the samples showed that the water can be stored for up to a maximum of 3 days. Therefore, super-hydrophilic sand particles were successfully prepared by coating them with PAM hydrogels, which have great potential to be used in sustainable desert agriculture.

Generality of Evaporative Crystal Liftoff on Heated Hydrophobic Substrates

Scaling or mineral fouling occurs due to the presence of dissolved minerals in water. Scaling is problematic in numerous industrial and household plumbing applications where water is used. The current methods of scale removal often utilize harsh chemicals that are not environmentally friendly. The evaporation of a saline droplet provides a platform to study the role of the substrate in the dynamics of crystallization during scaling. In the present work, we show out-of-plane growth of crystal deposits during the evaporation of saline droplets of aqueous potassium chloride on a heated smooth and microtextured hydrophobic substrate. These out-of-plane deposits, termed as "crystal legs", are in minimal contact with the substrate and can be easily removed from the substrate. The out-of-plane evaporative crystallization of saline droplets of different initial volumes and concentrations is observed irrespective of the chemistry of the hydrophobic coating and the crystal habits investigated. We attribute this general behavior of crystal legs to the growth and stacking of smaller crystals (size ∼10 μm) between the primary crystals toward the end of evaporation. We show that the rate at which the crystal legs grow increases with an increase in the substrate temperature. A mass conservation model is applied to predict the leg growth rate, which agrees well with the experiments.

3D Printed Platform for Impedimetric Sensing of Liquids and Microfluidic Channels.

Fused deposition modeling 3D printing (FDM-3DP) employing electrically conductive filaments has recently been recognized as an exceptionally attractive tool for the manufacture of sensing devices. However, capabilities of 3DP electrodes to measure electric properties of materials have not yet been explored. To bridge this gap, we employ bimaterial FDM-3DP combining electrically conductive and insulating filaments to build an integrated platform for sensing conductivity and permittivity of liquids by impedance measurements. The functionality of the device is demonstrated by measuring conductivity of aqueous potassium chloride solution and bottled water samples and permittivity of water, ethanol, and their mixtures. We further implement an original idea of applying impedance measurements to investigate dimensions of 3DP channels as base structures of microfluidic devices, complemented by their optical microscopic analysis. We demonstrate that FDM-3DP allows the manufacture of microchannels of width down to 80 μm.

Anticorrosive Polymeric Coatings

Abstract In order to improve the anticorrosion protection properties, polypyrrole thin films were deposited on silicon steel plates. The anticorrosive protection effect of the polypriol coating was evaluated by electrochemical measurements in two different aqueous solutions of potassium chloride and hydrochloric acid. Polypyrrole-coated silicon steel plates were immersed for one and seven days, respectively. The obtained results show that the thin layer of polypyrrole ensures effective protection of silicon steel against corrosion, especially in aqueous potassium chloride solution.

Microfluidic Platform with Serpentine Geometry Providing Chaotic Mixing in Induction Time Experiments.

We present a droplet microfluidic platform mixing the contents of the droplet chaotically in microfluidic induction time measurements, a promising method for quantifying nucleation kinetics with minute amounts of solute. The nucleation kinetics of aqueous potassium chloride droplets dispersed in mineral oil without surfactants is quantified in the presence and absence of chaotic mixing. We demonstrate the ability of the proposed platform to dictate droplet size, to provide a homogeneous temperature distribution, and to chaotically mix the droplet contents. Chaotic mixing in induction time measurements is facilitated by the motion of droplets through serpentine micromixer bends, while the extent of mixing is controlled by how much droplets move. Different nucleation kinetics are observed in experiments where the droplets are static, mixed, and in motion. We hypothesize that the droplet motion induces formation of a thin-liquid Bretherton film surrounding the droplets. The thin film shields droplets from solid boundaries that are more efficient heteronucleant surfaces compared to liquid–liquid interfaces. We observed that repeated microfluidic induction time measurements, particularly with moving droplets, produce significantly distinct cumulative nucleation probability curves, indicating that the measured nucleation kinetics depend strongly on the details of the experimental procedure, which we discuss in detail. Finally, we compare the microfluidic experiments to well-mixed, milliliter volume, turbidity-based measurements in the context of classic nucleation theory.

An insight into the thermodynamic investigation of important metabolite(KCl)-methyl nicotinate in aqueous solution at various temperatures

We report in this communication, the data on density and speed of sound measurements for methyl nicotinate in aqueous and in 0.1 mol.kg−1 aqueous potassium chloride solutions and potassium chloride (KCl) in water and in mixture containing fixed concentration (0.1 mol.kg−1) of Methyl nicotinate (MN) solution and varying the concentration (0.01 mol.kg−1 to 0.16 mol.kg−1) at 288.15, 293.15, 298.15, 303.15, 308.15, 313.15 and 318.15 K and atmospheric pressure. The density data are used to measure apparent molar volume of solute at finite concentrations(Vϕ) and apparent molar volume of solute at infinitely dilute solutions (Vϕ0) in binary and ternary mixtures. The speed of sound data are used to measure isentropic compressibility (κS), apparent molar isentropic compressibility of solute at finite concentrations (KS,ϕ) and apparent molar compressibility of solute at infinitely dilute solutions (KS,ϕ0) for binary and ternary mixtures . The coefficient of thermal expansion (α), apparent molar expansivity of solute (Eϕ) and limiting apparent molar expansivity (Eϕ0) of solute for binary and ternary solutions at 293.15, 298.15, 303.15, 308.15 and 313.15 K have also been measured. These parameters are being used to assist in the exploration of feasible intermolecular interactions in studied binary and ternary mixtures. The structure making/breaking ability of solute in binary and ternary solutions were also examined using Hepler's constant. All these results are analyzed and discussed on the basis of solute–solute and solute–solvent interactions.

In Silico Drug Design of Benzothiadiazine Derivatives Interacting with Phospholipid Cell Membranes.

The use of drugs derived from benzothiadiazine, a bicyclic heterocyclic benzene derivative, has become a widespread treatment for diseases such as hypertension, low blood sugar or the human immunodeficiency virus, among others. In this work we have investigated the interactions of benzothiadiazine and four of its derivatives designed in silico with model zwitterionic cell membranes formed by dioleoylphosphatidylcholine, 1,2-dioleoyl-sn-glycero-3-phosphoserine and cholesterol at the liquid–crystal phase inside aqueous potassium chloride solution. We have elucidated the local structure of benzothiadiazine by means of microsecond molecular dynamics simulations of systems including a benzothiadiazine molecule or one of its derivatives. Such derivatives were obtained by the substitution of a single hydrogen site of benzothiadiazine by two different classes of chemical groups, one of them electron-donating groups (methyl and ethyl) and another one by electron-accepting groups (fluorine and trifluoromethyl). Our data have revealed that benzothiadiazine derivatives have a strong affinity to stay at the cell membrane interface although their solvation characteristics can vary significantly—they can be fully solvated by water in short periods of time or continuously attached to specific lipid sites during intervals of 10–70 ns. Furthermore, benzothiadiazines are able to bind lipids and cholesterol chains by means of single and double hydrogen-bonds of characteristic lengths between 1.6 and 2.1 Å.

A new approach to investigate the ionic conductivity of NaCl and KCl solutions via impedance spectroscopy

Lima et al. [1] employed electrical impedance spectroscopy to analyze the electrical impedance behavior of dilute aqueous potassium chloride (KCl) and sodium chloride solutions in the frequency range of 10−1 Hz to 106 Hz (NaCl). The complex impedance Z* data from the solutions were modeled using an analogous electrical circuit that closely matched the experimental data. The electrical characteristics of the solutions were studied as a function of the cation types. The Debye model accurately describes the bulk effects of K+ and Na+ cations. However, it appeared that the analysis presented just the equivalent circuit components as a function of salt concentration. As a result, the current work used a simulation procedure to generate complex impedance (Z*) data from electrical parameters derived from the analogous circuit. To highlight the high-frequency relaxation processes occurring, extrapolation to a broader frequency range was performed. Furthermore, theoretical considerations were introduced in order to derive complex conductivity (σ*) from complex admittance (Y*). In the complex impedance (Z*) and admittance (Y*), there was a good correlation between all parameters derived from both processes. The key relaxation process characteristics, such as ionic strength, relaxation time, and conductivity values at low and high frequencies, were then retrieved. As a function of salt concentration, all of these parameters were evaluated and discussed.

Revisiting the salt-triggered self-assembly in very hydrophilic triblock copolymer Pluronic® F88 using multitechnique approach

An insight scrutiny into the micellization behavior of a linear triblock copolymer Pluronic® F88 in aqueous potassium chloride (KCl) solutions is put forth through various physicochemical techniques, viz. cloud point, tensiometric, microcalorimetry, fluorescence life-time decay, spectral, and scattering. Phase transitions of 5% w/v F88 in KCl electrolyte environment demonstrated the dehydration of copolymer coil; a decrease in the micellization temperature with increase in [KCl] due to salting out effect was configured with high sensitivity differential scanning calorimetry (HSDSC) and fluorescence spectroscopy conduct. Salting out effect exhibited by PEO and PPO blocks of F88 in the presence of KCl was measured by the variations in the bond stretching, intensity of vibrations, and change in chemical shifts using spectral (Fourier-transfer infrared (FT-IR) and 1H-nuclear magnetic resonance (1H-NMR) spectroscopy) techniques. The micellization that followed the double-relaxation process is further validated, employing ultrasonic absorption spectroscopy. The plausible unimers to spherical micelles transition induced by KCl are confirmed with the measured hydrodynamic diameter (Dh) of micelles using dynamic light scattering (DLS). Furthermore, UV-vis spectroscopy findings depicted the successive solubilization of water-insoluble organic dye (orange-OT) in the examined micellar solution which revealed the salient role of salt-water interaction in emboldening the micellization of F88.

Comparative study of electrosorption performance of solar reduced graphene oxide in flow-between and flow-through capacitive deionization architectures

There are a large number of capacitive deionization (CDI) cell architectures developed with different levels of complexities associated. Here, we compare flow-between (FB-CDI) and flow-through (FTE-CDI) capacitive deionization setups with respect to electrosorption performances by using solar reduced graphene oxide (SRGO) as an electrode material. SRGO is synthesised using solar irradiation and characterized for crystallinity, structure and morphology using x-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM). The electrode material is studied for charge storage using cyclic voltammetry and galvanostatic charge-discharge in aqueous sodium chloride and potassium chloride solutions. To compare the two capacitive deionization architectures with respect to electrosorption performance, we use two different cations, i.e sodium and potassium to study its effect on hydrated radius and hydration ratio of these cations. The electrosorption performance is estimated by varying the voltage between two electrodes and concentrations of salt solutions. The electrosorption capacity obtained is high 46.1 mg/g for FTE-CDI, whereas electrosorption rate is high i.e 0.026 mg/g/s for FB-CDI for potassium chloride solution. Further the obtained values of electrosorption capacities are validated by Langmuir and Freundlich adsorption isotherms. We confirm that the data fits well with Langmuir adsorption isotherm for both the cations. We further validate the electrosorption data by modified Donnan (mD) model.

Single-Coil Magnetic Induction Tomography Using the LDC-1101 Chip

Single-coil magnetic induction tomography (MIT) has thus far relied upon traditional bridge techniques to measure inductive losses, falling well under ~1 ohm. These measurements have been plagued by both noise and especially drift. This work considers methods based upon the Texas Instruments LDC-1101 chip, which measures LC circuit admittance while in resonance, from which we compute loss. Inductive loss is measured in a 4.0 cm diameter circular loop coil and compared with a quantitative theoretical result while the coil is axially positioned above a 2% aqueous potassium chloride solution contained in a 14 cm diameter petri dish filled to a depth of 2.0 cm. Results accurately capture the tail behavior of inductive loss as a function of coil-target distance. Then, using IR camera technology to track coil position, several `manual' scans are performed over phantoms prepared from sodium chloride-doped agarose components. In particular, this work considers the ability of single coil scans to capture corners of square plugs, gaps between plugs and side-by-side plugs that differ in conductivity. With drift and noise greatly reduced, the role of sample size is tested, showing that going beyond about 350 samples produces little further benefit to image quality. Though coil position is tracked to within ±0.25 mm, the random nature of manual positioning suggests that a more deliberate positioning scheme is needed, e.g. robotically.

Designing Selective Electrode Materials for Electroanalysis –New Tungsten Bronzes as Selective Potassium Hosts

AbstractCommercially available monoclinic tungsten oxide WO3 (Pearson symbol mP32) is investigated electrochemically for its selectivity and sensitivity towards potassium ion detection. Electroreduction in aqueous potassium chloride solution shows two distinct phases, identified as tungsten bronzes KxWO3 (phase 1: maximum x1 0.1 and phase 2: maximum x2≈0.3). In situ synchrotron powder X‐ray diffraction reveals the concomitant structural changes, and both phases are identified as new, so far unreported, perovskite‐derived potassium bronzes (space group P4/nmm and I 3 m, respectively). In cyclic voltammetry, only the first insertion step is found to be reversible. Potentiostatic insertion and the subsequent voltammetric de‐insertion show selectivity toward potassium against lithium and sodium in 0.1 M aqueous solutions. The sensitivity towards potassium is analysed in a concentration range between 1 mM and 100 mM. Two linear regions are found for the response, which we relate to two different rate‐determining steps, depending on the concentration of potassium in solution.