Solutions Of Potassium Salts Research Articles

Absorption of CO2 into Aqueous Potassium Salt Solutions of l-Alanine and l-Proline

Aqueous potassium salt solutions of l-alanine and l-proline were investigated as carbon dioxide (CO2) absorbents. The CO2 absorption capacities and absorption heats (−ΔHabs) of the aqueous amino acid salts were measured in a semi-batch absorption system and differential reaction calorimeter (DRC). The solution experiments tested concentrations of 2.5 M and were carried out at 298 and 313 K. The 13C and 1H nuclear magnetic resonance (NMR) spectra were used to identify the species distributions in the CO2-loaded absorbents. The absorption properties were compared to those of the commercial monoethanolamine (MEA) absorbent, revealing that the CO2 loading capacity was higher than that of MEA (0.68 mol of CO2/mol of solute for the potassium salt of l-alanine > 0.5 mol of CO2/mol of solute for MEA). The absorption heat was lower than that of MEA at 298 K (53.26 kJ/mol of CO2 for the potassium salt of l-alanine < 81.77 kJ/mol of CO2 for MEA).

Synthesis, Langmuir and Langmuir–Blodgett films of a calix[7]arene ethyl ester

Calixarenes are promising compounds to be used as ionophores and for molecular recognition. Their ability to form Langmuir and Langmuir–Blodgett (LB) films is of great interest in order to obtain small sensor devices which incorporate an active nanometric film. The p-tert-butylcalix[7]arene ethyl ester compound has been synthesised and its ability to form Langmuir and LB films has been shown. This macrocycle forms monolayers but it tends to form multilayers at higher compressions, as corroborated by AFM. BAM images show a uniform layer till the multilayer process occurs and a good correspondence with the features of the surface pressure–area isotherm. AFM images reveal that, in water subphase, films are quite homogeneous but the presence of small islands has also been observed. The presence of ions in the subphase, as sodium, potassium, rubidium, cesium, calcium, barium, cadmium and tin chloride salt solutions, leads to some changes in the surface pressure–area isotherms, but the more important changes are observed by AFM. More uniform films are observed for rubidium, cesium, cadmium and tin ions. A very different nanometric structure has been observed for tin ions. Some characteristics of the films, molecular area and height, are correlated with molecular modelling calculations.

Dual and tetraelectrode QCMs using imprinted polymers as receptors for ions and neutral analytes

Polymers as coating materials were combined with quartz crystal microbalances (QCMs) to design sensor devices for the detection of both ionic and neutral analytes in liquid phase. The design and geometry of dual and tetraelectrode QCMs have been optimized to reduce electric field interferences. An unusual Sauerbrey effect was observed while exposing potassium salt solution to 10- and 20-MHz QCMs, i.e. increase in the frequency shifts by a factor of seven, which is attributed to electro-acoustic phenomena. Non-functionalized sol-gel materials were synthesized by templating with hydrophobic salt such as tetraethyl ammonium picrate. Imprinting with these ions of low charge density leads to sensitive layers, and UV-Vis spectroscopy was used to check re-inclusion of this analyte. In the next strategy, functionalized polyurethane for potassium ions and sol-gel materials with aminopropyl group as ligand were generated to tune selectivity and sensitivity towards Ni(2+) and Cu(2+). Methacrylic acid polymers were optimized for the detection of atrazine by hydrogen bonding; double molecular imprinted polyurethane approach was followed for pyrene recognition. Finally, these imprinted polymers were combined with tetraelectrode QCM to develop sensor platform.

Dissipative crystallization of potassium salt of poly(riboadenylic acid)

Dissipative patterns during the course of dryness of aqueous solution of potassium salt of poly(riboadenylic acid) (KPolyA) in the presence of potassium chloride were studied on a cover glass, a watch glass and a glass dish. Accumulation of KPolyA polymers forming the broad ring area and the drastic change in size and shape of the polymer single crystals depending on the location of the dried film, which are the typical effects of the dissipative crystallization, took place. Polymer crystals formed were spherulites, dendritic and rod-like assemblies, which are composed of the single or double helical chains depending on the pH-value of the initial solution.

Cold Gelation of Alginates Induced by Monovalent Cations

A new reversible gelation pathway is described for alginates in aqueous media. From various samples differing by their mannuronic/guluronic content (M/G), both enthalpic and viscoelastic experiments demonstrate that alginates having a high M content are able to form thermoreversible assemblies in the presence of potassium salts. The aggregation behavior is driven by the low solubility of M-blocks at low temperature and high ionic strength. In semidilute solutions, responsive assemblies induce a strong increase of the viscosity below a critical temperature. A true physical gel is obtained in the entangled regime, although the length scale of specific interactions between M-blocks decreases with increasing density of entanglements. Cold setting takes place at low temperatures, below 0 °C for potassium concentrations lower than 0.2 mol/kg, but the aggregation process can be easily shifted to higher temperatures by increasing the salt concentration. The self-assembling process of alginates in solution of potassium salts is characterized by a sharp gelation exotherm and a broad melting endotherm with a large hysteresis of 20-30 °C between the transition temperatures. The viscoelastic properties of alginate gels in potassium salts closely depend on thermal treatment (rate of cooling, time, and temperature of storage), polymer and salt concentrations, and monomer composition as well. In the case of alginates with a high G content, a similar aggregation behavior is also evidenced at higher salt concentrations, but the extent of the self-assembling process remains too weak to develop a true gelation behavior in solution.

Water solutions of phenosan potassium salt: Influence on biological membrane structure and conductivity

Water solutions of phenosan potassium salt: Influence on biological membrane structure and conductivity

Insights on the Mechanism of Insoluble-to-Soluble Prussian Blue Transformation

The electrochemical transformation of the soluble form of Prussian blue (PB) material from the insoluble form was monitored using electrochemical, gravimetric, acoustic, and spectroscopic techniques simultaneously. The described combination of in situ techniques represents an innovative tool for measurement in electrochemistry, which provides complementary information on the electrochemical systems. The insoluble-to-soluble PB transformation process takes place during the successive voltammetric cycles between the mixed valence form (PB) and the fully reduced form [Everitt’s salt (ES)]. One of the processes that takes place is the exit of free ions occluded in the vacancies of the insoluble PB crystalline framework during the fresh PB electrodeposit process. In potassium salt solutions, the exit of each ferrocyanide ion is compensated by the entrance of two potassium ions and six hydroxyl anions. This species exchange increases the manifestation of viscoelastic phenomena of the rigid skeleton from the insoluble PB form to the soluble one, which could facilitate the appearance of an internal magnetic field at room temperature during the soluble voltammetric cycle.

Isolation of niobium, tantalum, and titanium complex fluoride salts with alkali metal cations

Fluoride and oxofluoride salts of niobium, tantalum, and titanium were isolated. They precipitated from aqueous solutions and upon washing of organic extracts with aqueous solutions of ammonium, potassium, and sodium salts. The compositions of the isolated compounds were studied. Different compositions were established for the niobium salts that precipitated upon the dissolution of unwashed niobium hydroxide in hydrofluoric acid under the atmospheric pressure, in an autoclave, and upon addition of sodium, potassium, and ammonium salts to purely fluoride solutions of niobium, as well as for the tantalum ammonium and sodium salts isolated from aqueous and organic solutions. The data obtained can be used for the synthesis of niobium, tantalum, and titanium complex fluoride salts with various compositions.

Observation of the matrix effect due to the electron transfer in laser ablation plasma

We investigate the so-called “matrix effect” on the relative intensities of ions in mixed solutions of alkali salts by using femtosecond laser ablation time-of-flight mass spectrometry (fsLA-TOFMS). For the 1:1 mixed solution of sodium and potassium salts, the intensity ratio of cations (Na+/K+) decreases as the total concentration increases. From the measurement for the mixed solution of lithium, sodium, potassium, rubidium, and cesium solutions, we find out significant dependence of each ion intensity on the total concentration. The results suggest that the electron transfer from neutral atoms to cations coexistent in the ablation plasma affects the relative ion intensities observed with TOFMS when the total ion concentration is high.

Oral potassium supplementation in surgical patients

Hospital inpatients are frequently hypokalaemic. Low plasma potassium levels may cause life threatening complications, such as cardiac arrhythmias. Potassium supplementation may be administered parenterally or enterally. Oral potassium supplements have been associated with oesophageal ulceration, strictures and gastritis. An alternative to potassium salt tablets or solution is dietary modification with potassium rich food stuffs, which has been proven to be a safe and effective method for potassium supplementation. The potassium content of one medium banana is equivalent to a 12 mmol potassium salt tablet. Potassium supplementation by dietary modification has been shown to be equally efficacious to oral potassium salt supplementation and is preferred by the majority of patients. Subsequently, it is our practice to replace potassium using dietary modification, particularly in surgical patients having undergone oesophagogastrectomy or in those with peptic ulcer disease.

Evaluation of Equine Laminar Vein Function: Harvesting, dissection and the use of functional methods to distinguish between veins and arteries

Introduction Pharmacological evaluation of the unique equine laminar microvasculature is crucial to understanding its role in health and in diseases such as laminitis. However, separating the distinctive characteristics of arterial versus venous components of this complex vascular network has previously proved to be extremely difficult. Encased in a hard hoof capsule, isolation of individual blood vessels presents a considerable challenge. Exacerbating this difficulty, the laminar venous network is adapted to sustain high intravascular pressures and consequently has thickened walls, making the normally straightforward visual distinction between arteries and veins problematic. Here we describe a novel harvesting and dissection method coupled with a functional analysis procedure that facilitates distinction of arteries and veins. Methods Laminar tissue was recovered from the hoof of euthanized, clinically normal horses by dissection at the coronary band and stored in cold Krebs–Henseleit physiological salt solution prior to further dissection in the laboratory to remove 2 mm segments of vessels 100–500 µm in diameter. Active length tension measurements were made to evaluate optimal conditions for experimentation, and based on the differences in contractility and appearance, an experimental protocol was set up to allow a) initial distinction between arteries and veins and b) in vitro pharmacological evaluation. Results Active length tension studies clearly revealed the presence of two populations of vessels distinguished by either a large or a lower maximal contraction that subsequent histological evaluation confirmed to be arteries and veins respectively. Functional distinction using relative contractility to 60 mM potassium salt solution then demonstrated equine laminar veins to have increased sensitivity to the agonist endothelin 1 (ET-1) compared to arteries. Discussion In vitro evaluation of laminar vessels is possible despite anatomical obstacles. Furthermore, a clear distinction can be made between laminar veins and arteries using functional characteristics providing vessels of a similar size range are selected. Utilising these novel procedures, investigators can unambiguously analyse the pharmacological characteristics of equine laminar veins and arteries to decipher the physiological mechanisms responsible for the control of laminar blood flow.

Enhanced Copper Surface Protection in Aqueous Solutions Containing Short-Chain Alkanoic Acid Potassium Salts

The ability of dissolved potassium monocarboxylate salts to produce surface passivation and to inhibit aqueous corrosion of copper was studied. The electrochemical measurements indicate that the inhibiting efficiency of these compounds, with a general formula Cn-1H2n-1COOK or CnK (n=3...12), is dependent on the hydrocarbon chain length. The inhibiting efficiency was higher for a longer hydrocarbon chain of n-alkanoic acid. The degree of copper protection was found to increase with an increase in n-alkanoic acid potassium salt concentration; the optimum concentration of potassium dodecanoate (C12K) in sulfate solutions was found to be 0.07 M. The protective layers formed at the copper surface subsequent to exposure in various n-alkanoic acid potassium salt solutions were characterized by contact angle measurements, electrochemical impedance spectroscopy, X-ray photoelectron spectroscopy, and Fourier transform infrared reflection spectroscopy. Pronounced copper protection was attributed to the growth of a protective film on the copper surface, containing both copper oxides and copper carboxylate compounds. It is suggested that the organic molecules enhance copper protection by covering copper oxides with a thin and dense organic layer, which prevents water molecules or aggressive anions from interacting with the copper surface.

Self-organization of guanosine 5′-monophosphate on mica

Self-assembled aggregates of guanosine 5′-monophosphate (GMP) on the surface of muscovite mica were investigated by atomic force microscopy (AFM). Aqueous solutions of sodium, potassium and ammonium GMP salts were studied. For solution concentrations c < 0.005 wt% only small islands of deposited material are present on the surface. For c ∼ 0.02 wt%, in addition to the islands and patches, also linear aggregates called G-wires are formed. The wire-like aggregates are on average 1.9 nm high and can be several micrometers long. They exhibit a profound directional growth along the six main crystallographic axes of the basal plane of mica. For c > 0.1 wt% flat terraces with the height of 2.5 nm appear. They are formed of G-wires lying with their long axis parallel to the substrate and stacking in a hexagonal arrangement. The morphology of the adsorbates is independent of the type of salt used to prepare the initial solution. This signifies that intrinsic potassium ions from the substrate play much more important role in the GMP adsorption than cations from the solution.

Optical emission spectroscopy of diaphragm discharge in water solutions

This work is focused on optical emission spectroscopy observations of DC non-pulsed diaphragm discharge in various water solutions of sodium and potassium salts. The emission intensity dependencies of hydrogen, oxygen, and alkaline metal lines on the salt kind are studied and compared also with respect to the initial solution conductivity. The hydrogen and oxygen intensities increase more or less linearly with the increasing solution conductivity. The sodium intensity behaves identically, but the potassium intensity decreases with the conductivity increase. The hydrogen intensity is higher in the case of salts containing potassium. The dependence of the Hα line intensity on the salt kind is lower than if a sodium salt is used. The oxygen emission is more or less independent on the used salt. In addition, the rotational temperature from the OH radical spectrum is calculated for the investigated electrolytes and it is in the range from 500 to 900 K, according to the initial solution conductivity. The dependence of the rotational temperature on the salt kind is not clear so far.

A Simple Method for the Synthesis of Tetrabutylammonium Hexachlorometalates

A convenient - and quick to realize - approach for the synthesis of tetrabutylammonium hexachlorometalates (Bu4N)2[MCl6] is suggested. Since the preparation of (Bu4N)2[MCl6] (M=Re, Os, Ir) by simple one-pot method is hitherto unreported, we successfully synthesized it by simply mixing the tetrabutylammonium hydroxide with acidic solution of potassium salt of hexachlorometalates.

Influence of K + Ions on the Interaction of Water with Silicon Dioxide at Low Temperature Relevant to CMP

Internal reflection infrared spectroscopy was used to examine the effect of potassium ions on the interaction of water with silicon dioxide at low temperature, relevant to chemical mechanical planarization (CMP) of silicon dioxide. Silanol (SiOH) formation was enhanced in silicon dioxide samples exposed to aqueous solutions of potassium chloride and potassium nitrate as compared to those exposed to water, due to a reduction in the thermodynamic activity of the water in potassium salt solutions. However, molecular water was the predominant hydrous species observed in the silicon dioxide. The presence of potassium ions had no significant effect on the effective diffusion coefficient of water in silicon dioxide. Results presented here indicate that the potassium ion concentration, and more specifically the water activity, is a critical factor in the chemical component of the silicon dioxide CMP mechanism. © 2004 The Electrochemical Society. All rights reserved.

Structural and physiological properties of natural petroleum acids from middle oil fractions of "Kelebija" oil

The investigated petroleum acids have been isolated from middle oil fractions (b.p. 270-380?C) of Vojvodina crude oil "Kelebija." Group-structural analysis was performed with low resolution mass spectrometry using Field Ionization and Chemical Ionization. The identified carboxylic acids, CnH2n+zO2, belong to the series of monocyclic, bicyclic, tricyclic and tetracyclic carboxylic acids. Physiological activity of isolated petroleum acids was determined using aqueous solutions of potassium salts. High auxin activity was determined using the coleoptile test (20.5% increase in coleoptile) with petroleum acid concentration of 10-7M, and very high biological activity of gibberellin type was determined using the endosperm test (31.6% increase in concentration of reducing sugars) with petroleum acid concentration of 10-7M.

Adsorption of cadmium on acid-modified Transcarpathian clinoptilolite

The adsorption properties of acid-modified Ukrainian Transcarpathian clinoptilolite towards aqueous cadmium(II) solutions under dynamic conditions have been investigated. It has been demonstrated that the adsorption capacity of the H-form of clinoptilolite depends on the nature and concentration of acid as well as the duration of contact of clinoptilolite with acid in the process of modification. The most effective adsorption of cadmium(II) was demonstrated by clinoptilolite pre-treated with 1 M of HCl during 24 h. It has been determined that the optimum for concentration of cadmium(II) is the H-form of clinoptilolite obtained without considerable dealumination. Under optimum conditions (diameter of zeolite grains equal to ca. 0.20–0.30 mm; flow rate of cadmium(II) solution of 500 ng/ml concentration through adsorbent equal to 3 ml/min; pH=5.6) the dynamic absorption capacity is 7.41 mg of cadmium per 1 g of acid-modified clinoptilolite. The conditions of desorption of cadmium from acid-modified clinoptilolite have been investigated. The solutions of potassium salts are the best desorbent of the ones that have been approved. The extraction of cadmium in these solutions reaches 88–92%.

Apparent and partial molar enthalpies of some potassium p- n-alkyl-benzoate aqueous solutions

Dilution heats at 298 K of aqueous solutions of potassium salts of p- n-hexylbenzoic acid (KHB), p- n-heptylbenzoic acid (KHEB), p- n-octylbenzoic acid (KOB) in KOH 0.1 m have been measured as a function of concentration by using the flow mixing cell of a Thermometric TAM microcalorimeter. From the experimental data, apparent and partial molar enthalpies versus concentration have been obtained. The group contribution of the CH 2 group in the plateau region results −1.6 kJ mol −1 per CH 2. This value is comparable with that obtained in the case of cationic surfactants. The enthalpy changes upon micellization (Δ H m ) have been obtained by using a pseudo phase transition approach and assuming as cmc the abscissa of the first inflection point of the curves of Φ L versus m. Micellization enthalpies result additive with a group contribution for the methylene group of −1.5 kJ mol −1 per group, comparable with that obtained for similar anionic compounds in the same experimental conditions. The behavior of the compounds under study is compared with that of the potassium salts of 4-((alkylcarbonyl)amino)-benzoic acids in order to understand the role played by the amido group bridging the benzoic moiety and the alkyl chain. The amido group appears to behave as a part of the polar head, strongly increasing the hydrophilicity of the molecule.

Uptake of aluminum by intact canola seedlings

Aluminum (Al) ions were taken up from a liquid nutrient solution by roots of intact canola (Brassica napus var. napus L.) seedlings in two stages. A rapid initial phase, which was complete within 30 to 45 min, was followed by a slower secondary phase that leveled off after approximately 12 h. Approximately 55% of Al taken up within 12 h was estimated to remain in the apoplasm and less than 10% was translocated to the shoots. Uptake of Al was increased by placing canola seedlings in the dark or removing the shoots, which indicated that canola roots seemed to have an energy dependent mechanism for excluding Al. Incubating seedlings in different desorbing solutions suggested that accumulated Al was bound at different sites in the roots. Organic acids, particularly citrate, were more effective than dilute solutions of magnesium (Mg), potassium (K), and calcium (Ca) salts in bringing about the release of Al from canola roots.