Aqueous Potassium Chloride Solutions Research Articles

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.

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.

Potassium chloride passivation for sputtered SnO2 to eliminate hysteresis and enhance the efficiency of perovskite solar cells

In perovskite solar cells (PSCs), tin oxide (SnO2) has been widely used as the electron transport layer (ETL) due to its wide bandgap and high electron mobility. Among the various deposition methods, radio frequency (RF) sputtering offers many advantages for the commercialization of PSCs fabrication. However, conventional PSCs with sputtered SnO2 are subject to severe hysteresis, which occurs owing to defect sites at the ETL-perovskite interface. Further, these defect sites induce non-radiative carrier recombination, causing a decrease in open-circuit voltage and device fill factor. Herein, the surface of RF-sputtered SnO2 was passivated with potassium chloride (KCl) aqueous solution. Through this treatment, it was possible to passivate the defect sites at the interface and change the band alignment for effective electron transport. Thus, a decrease in the trap density of the perovskite led to an increase in efficiency (from 20.9% to 21.9%) and reduction in the hysteresis (from 10.5% to 2.7%) of the PSC. Hence, the KCl passivation process of RF-sputtered SnO2 could be adopted to manufacture hysteresis-free high-efficiency PSCs.

Synthesis and electrochemical properties of sulfur-nitrogen-doped multi-walled carbon nanotubes

Multi-walled carbon nanotubes doped with sulfur and nitrogen (S-N-MWCNTs) were grown onto silicon/silicon oxide wafer by means of chemical vapor deposition upon decomposition of dimethyl sulfoxide (DMSO) and acetonitrile (ACN) in presence of catalyst. The S-N-MWCNTs were characterized by scanning electron microscopy combined with energy dispersive X-ray spectroscopy. The findings demonstrate that S-N-MWCNTs exhibit bamboo-shaped nanostructure, quite similar to pure nitrogen-doped carbon nanotubes. The S-N-MWCNTs were investigated with respect to their electrochemical response to ferrocyanide/ferricyanide, [Fe(CN)6]4-/3- in potassium chloride aqueous solutions by means of cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) techniques. The recorded CVs demonstrate strong dependence of electrochemical response, electron transfer kinetics, and sensitivity of S-N-MWCNTs on concentration of decomposed DMSO precursor. Namely, upon increasing concentration of decayed DMSO up to 2% wt. the current density, the electron transfer kinetics, and the sensitivity of S-N-MWCNTs toward [Fe(CN)6]4-/3- tend to enhance. The extracted EIS results approve that when DMSO reaches the optimum concentration of 2% wt. the barrier for electron transfer decreases significantly leading, consequently, to faster electron transfer kinetics. The S-N-MWCNTs exhibit considerable stability and excellent reproducibility, and thus it can be considered suitable analytical tool for detection of redox systems at micromolar level.

Magnesium nanoparticles as a highly stable anode for the electrochemical cell

The chemical route for synthesis of magnesium nanoparticles serving as an active material for the nanocomposite anode with the conductive polymeric matrix is described. The electrochemical characteristics of the produced anode is investigated and compared with those of the counterpart anode made of micro-scale Mg particles. The energy density at 10 mA for the anode incorporating Mg nanoparticles (169.1 ± 10.8 W∙h/kg) is 6.8 times higher than that for the anode with Mg microparticles (24.8 ± 6.7 W∙h/kg). It is shown that the nanocomposite anode possesses superior stability and discharge voltage in potassium chloride aqueous solution with respect to that incorporating coarse particles. High discharge voltage is kept due to the uniform distribution of agglomerates of Mg nanoparticles in the anode. Using the results of Fourier-transform infrared spectroscopy it is suggested that the high resistance to oxidation of anode with Mg nanoparticles can be the root-cause of the enhanced electrochemical performance of the anode.

Solubility and thermodynamical phenomenafor l-serine and l-isoleucine in chloride Salts of Na+ and K+ electrolytic media

The study of solubility and chemical thermodynamics of amino acids in aqueous and binary mixture of solvents give us ideas on the behaviors of biomolecules in industrial complex solvent system. Thus, here we have measured solubilities of two isostructural amino acids l-serine and l-isoleucine in aqueous and binary electrolytes solutions of sodium chloride (NaCl) and potassium chloride (KCl) respectively. This study was carried out using analytical gravimetric method at temperature range 288.15 K to 308.15 K. The obtained experimental saturated solubility values were used to derive the thermodynamics of solutions free energies. The free energetics of solvation due to transfer were then determined and explained properly. Different thermophysical characteristics in aqueous electrolytes media were assessed and correlated. A variety of chemical processes, the solubility and stability of amino acids were also explained in terms of solute–solvent, solvent–solvent, and acid-base interactions.

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.

Effect of acid-base properties of zirconium dioxide on dissolution kinetics

The processes of metal extraction from ores, in which metals can often be found as part of oxides and sulphides, involve stages of chemical or electrochemical dissolution. Few publications can be found in the literature that describe detailed research studies looking into how the surface phenomena of d-metal oxides are linked to the acid-base properties and the dissolution mechanics. Consequently, it would be of relevance to establish kinetic relationships of the processes related to the extraction of metals from lean ores and secondary raw materials, leaching and beneficiation, surface etching and purification. This paper describes the results of a study that relied on potentiometric titration in an aqueous solution of potassium chloride to understand the dissolution kinetics of zirconium dioxide suspension. Titration curves were produced for different concentrations of the background electrolyte and pH values and a relationship was established between ZrO2 dissolution kinetics and pH of the medium. Acid-base equilibrium constants were calculated at the metal oxide/electrolyte solution interface. The obtained results were used to analyze the distribution of surface particles that form as a result of hydrogen ions adsorption and desorption. Interpretation of the experimental relationships was based on comparison with theoretical calculations. The authors simulated the dissolution process. The paper demonstrates that metal oxides dissolve in stages, and adsorption complexes form in the process, the composition of which is linked to the surface charge. These findings could be useful when studying the kinetics of d-metal oxides, as well as in practical applications related to the dissolution of transition metal oxides in electrolyte solutions.

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.

Electric conductivity measurements employing 3D printed electrodes and cells

The electric conductivity is one the most routinely inspected characteristics of aqueous media, being employed in monitoring drinking water quality and determining thermodynamic properties of electrolytes. In this work, we utilize fused deposition modelling 3D printing (3DP) to manufacture a platform composed of supporting cells and sensing electrodes for electric conductivity measurements of aqueous solutions. For the first time, the electric conductivity of liquid electrolytes is sensed by 3DP electrodes, employing a direct electrode/electrolyte contact. Conductivity measurements performed in the presented 3DP platform are controlled by an electronic circuitry developed employing a programmable system on chip prototyping kit. The entire conductometric setup was validated employing commercial conductance standards as well as in-lab prepared aqueous solutions of potassium chloride and formic and acetic acid as representatives of strong and weak electrolytes. Conductivity measurements enabled the correct determination of limiting molar conductivity (for potassium chloride) and dissociation constants (for the two weak acids). Finally, the functionality of the presented platform was confirmed by measuring conductivity of various bottled water samples. Results obtained in this work pave the wave for further development and applications of conductometers based on 3DP electrodes and cells.

Study of Graphene Epoxy/Nanoplatelets Thin Films Subjected to Aging in Corrosive Environments

The corrosion of metallic devices and degradation of plastic materials are a cause of great concern for companies and countries’ economies; it is necessary to contrast these phenomena by studying innovative methodologies and techniques. A simple solution lies in the realization of materials that can resist corrosive environments and be used as coatings to prevent, or at least delay, deterioration. The purpose of this work was to study the behavior of an epoxy resin, in thin film form, exposed to corrosive chemicals. In particular, the samples were subjected to aging of 31 days in dilute sulfuric acid (H2SO4) and in an aqueous solution of potassium chloride (KCl). Subsequently, thin films of Epoxy/graphene nanoplatelets (GNP) composite material have been subjected to the same conditions: it was investigated how these samples respond to the corrosive environment. We found that the addition of carbonaceous nanofillers prolongs in time the ability of the material to resist the attack of chemical agents.

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.

Experimental study of cold storage packed domestic refrigerator with solar powered variable speed compressor

A domestic chest type freezer powered by photovoltaic solar panels studied experimentally. Phase change materials (PCM) were incorporated as thermal energy storage instead of traditional batteries for power backup freezer operation under absence/low solar irradiance levels. The test rig consists of three sided freezer divided into two insulated compartments each have its own PCM storage tank. A eutectic potassium chloride (19.4% with -10°C freezing temperature) and sodium chloride (8% with -5°C freezing temperature) aqueous solutions were used as thermal energy storage in each part of cabin. A comparison between different PCMs was made. The results showed a %54 reduction in compressor running time for the PCM packed evaporator. 4Kg of 8% NaCl solution at full load gave higher thermal mass. Also, freezer temperature maintained between -3.5 to -1 ºC for 46% of holdover periods without power supply. 8% NaCl solution performance was superior to 14% NaCl. As the mass of PCM increases the freezer performance improves as well. Finally, two compartments freezer showed that 2kg of 19.5% KCl has successfully kept load temperature at (2°C).

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.

Modeling of the Refractive Index for the Systems MX+H2O, M2X+H2O, H3BO3+MX+H2O, and H3BO3+M2X+H2O. M = K+, Na+, or Li+ and X = Cl− or SO42−

The modeling of the refractive index for binary aqueous solutions of boric acid, sodium chloride, potassium chloride, sodium sulfate, lithium sulfate, and potassium sulfate, as well as ternary aqueous solutions of boric acid in the presence of sodium sulfate, lithium sulfate, or potassium chloride, is reported. The refraction index was represented by molar refraction. It was described as the sum of solutes’ partial molar refraction and solvent molar refraction. The solutes’ partial molar refraction was estimated from the molar refraction of the binary solutions. The excess molar refraction for these systems was described with the equation of Wang et al. The polarizability of the solutes present in the studied systems was estimated using the Lorenz–Lorenz relation. The results showed the model is appropriate for describing the systems studied; the interactions of boric acid, sodium, potassium, lithium, chloride, and sulfate ions with water molecules are relevant to explain the molar refraction and refractive index, and those for the binary systems of lithium chloride and sodium chloride are also relevant the ion–ion interactions. The model is robust and presents estimation capabilities within and beyond the concentrations and temperature range studied. Therefore, the outcomes represent valuable information to understand and follow the industrial processing of natural brines.

Convective heat and mass transports and chaos in two-component systems: comparison of results of physically realistic boundary conditions with those of artificial ones

Linear and weakly nonlinear stability analyses of double-diffusive convection in two-component liquids with either potassium chloride (KCl) or sodium chloride (NaCl) aqueous solution, and heat being present is investigated in the paper for free, and rigid, isothermal, iso-solutal boundaries. Using the thermophysical values of the aqueous solutions, we have shown that the stationary convection is the preferred mode at onset and that sub-critical motion is possible. We found that the critical thermal Rayleigh number for water + NaCl + heat is higher compared to that of water + KCl+ heat. The study shows that for water + KCl + heat, the transition from convective motion to chaotic motion occurs at $$r_{\mathrm{H}}=27.2$$ for free boundaries and at 48.5 for rigid boundaries. Here, $$r_{\mathrm{H}}$$ denotes the Hopf thermal Rayleigh number. Further, the existence of windows of mildly chaotic points and fully periodic intervals are reported using Lyapunov exponents and bifurcation diagrams. Chaotic motions in both the aqueous solutions are nearly identical. The percentage increase in heat transport in the double-diffusive system involving NaCl is nearly 1% more than that of KCl in the case of free boundaries, whereas in the case of realistic boundaries it is nearly 1.6%. The comparison of the Nusselt and the Sherwood numbers between water + KCl and water + NaCl leads us to the conclusion that the aqueous solution with lower Lewis number transports maximum heat in the case of free boundaries and opposite is seen in the case of rigid boundaries due to the boundary effect. The many qualitative similarities between the results of artificial and realistic boundaries are highlighted.

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.