KI Solutions Research Articles

Effects of specific anions on the relationship between the ion-adsorption properties of sulfobetaine gel and its swelling behavior

The adsorption of cations and anions from four different halide solutions, i.e., KF, KCl, KBr, and KI solutions, onto N,N-dimethyl(acrylamidopropyl)ammonium propane sulfonate (DMAAPS) gels prepared using various cross-linker concentrations was investigated at a variety of temperatures; the swelling degrees of the gel in these solutions were also examined. The amount of K+ adsorbed coincided with the adsorption of the anions (i.e., I−, Br−, Cl−, or F−) because of simultaneous adsorption of the cations and anions onto DMAAPS gel. The order of anions, which gave larger amount of K+ adsorbed onto the gel, was opposite that of the Hofmeister series, i.e., I− > Br− > Cl− > F−. Furthermore, the relationship between the degree of swelling of the gel and amount of K+ adsorbed onto the gel was elucidated. The data points laid on the same line for the same halide solution even at different cross-linker concentrations or temperatures. At smaller degrees of swelling, the amount of K+ adsorbed remained unchanged and then decreased gradually as the degree of swelling increased. In solutions containing anions with lower hydration ability, such as KI, the amount of K+ adsorbed decreased at larger degrees of swelling. In contrast, in solutions containing anions with higher hydration abilities, such as KCl, the adsorbed amount of K+ decreased at smaller degrees of swelling. Additionally, it was found that, in mixtures of these halide solutions, competitive adsorption of anions occurred. Anions with lower hydration abilities adsorbed more readily in the mixtures than in the single-anion solution. In contrast, anions with higher hydration abilities adsorbed less readily in the mixtures than in the single-anion solution.

Chemisorption and Electrochemical Activity of Thiophenols at Well-Defined Pd(111) Surfaces: Studies by LEED, AES, HREELS, and Electrochemistry

The chemisorption and electrochemical activity of 2 ,5 -dihydroxythiophenol (DHT) and 2-(8mercaptooctyl)-1,4-benzenediol (DHOT) on well-defined Pd(111) surfaces were studied by Auger electron spectroscopy (AES), low energy electron diffraction (LEED), high resolution electron energyloss spectroscopy (HREELS), and electrochemistry (EC). Results confirm that DHT is chemisorbed in two discrete orientations such that at low concentrations, DHT is oxidatively bound to the surface through the diphenol and mercapto groups as quinonoid and S moieties, respectively, whereas at high concentrations, the molecule is coordinated oxidatively through the –SH group in a vertical S- η 1

ChemInform Abstract: Bad Metal Behavior in the New Hg‐Rich Amalgam KHg6 with Polar Metallic Bonding.

AbstractKHg6 is prepared by isothermal electrocrystallization in a solution of KI in DMF at 343 K using a reactive Hg infiltrated amalgamated Cu spoon cathode.

Bad metal behaviour in the new Hg-rich amalgam [formula omitted] with polar metallic bonding

The new mercury-rich amalgam KHg6 crystallises with the BaHg6 structure type (orthorhombic, space group Pnma (No. 62), a=13.394(9)Å, b=5.270(3)Å, c=10.463Å). It was prepared by electrolysis of a solution of KI in N,N′-Dimethylformamide at 343K at a reactive Hg cathode. The structure of KHg6 shows motifs of ionic packing, covalent Hg cluster formation and metallic properties. KHg6 decomposes peritectically at 443K. The combination of alkali metals with a noble metal with moderate electron affinity results in the formation of polar metal–metal bonding with considerable but incomplete electron transfer from the electropositive to the electronegative sublattice, resulting in typical “bad metal behaviour”, illustrated by resistance and susceptibility measurements and quantum theoretical calculations.

High Voltage AC/AC Capacitors Using the Carbon/Iodine Interface in Ionic Liquid Electrolyte

Lately we have demonstrated that huge pseudo-capacitive contributions can be originated from the electrolyte when using high surface area activated carbon electrodes, for example by using iodide based solutions in water [1]. Although the use of such concept allows very high capacitance values to be reached, the energy of the AC/AC capacitors based on these electrolytes is limited by the relatively low value of voltage inherent to use of water. Therefore, in this work, we have investigated the performance of the carbon/iodine interface in ionic liquid electrolytes, both protic (PIL) and aprotic (AIL).The PILs selected were triethylammonium bis(tetrafluoromethylsulfonyl)imide [Et3NH]-[TFSI] and 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide [Emim]-[FSI]. Organic iodides - triethylammonium iodide [Et3NH]-[I] and tetraethylammonium iodide [Et4N]-[I] at a concentration of 0.25 mol·L-1 and inorganic iodides (LiI and KI) at a concentration of 0.2 mol·L-1 were introduced in the ionic liquid. The electrochemical experiments as cyclic voltammetry, galvanostatic charge/discharge and impedance spectroscopy were conducted using a two-electrode cell construction. In some experiments, a silver wire was added as pseudo-reference to monitor the potential of individual electrodes. Activated carbon (AC) activated by KOH (4:1) with high microporosity ( SBET = 2180 m2·g-1, Vmicro = 0.96 cm3·g-1, L0 = 1.55 nm) was used as working and counter electrode. Glass microfiber paper (Whatman) was utilized as separator.Galvanostatic (0.2 A·g-1) cycling up to 1.8 V in two-electrode cell with reference electrode (Figure 1B) demonstrates a remarkable increase of capacitance when KI is added to [Et3NH]-[TFSI], from 122 to 184 F·g-1. The voltammograms of figure 1A show clearly that the increase of capacitance is caused by the positive electrode where faradaic processes occur. The capacitance values of the positive electrode for 0.25 mol·L-1 [Et3NH]-[I] and 0.2 mol·L-1 LiI dissolved in [Et3NH]-[TFSI] reached 199 and 238 F·g-1 , respectively; for the negative electrode the capacitance reached 163 and 121 F·g-1 , respectively. The addition of 0.2 mol·L-1 inorganic iodide to aprotic IL also enhanced the capacitance from 116 F·g-1 for the pure AIL to 129 and 153 F·g-1for the KI and LiI solutions, respectively. Regardless of the different type of iodide derivatives dissolved in IL medium, faradaic processes occur at the positive electrode greatly increasing the capacitance of the whole capacitor system. However, iodide solutions in PILs seem to be more effective than the AILs ones. Acknowledgements:The Foundation for Polish Science is acknowledged for supporting the ECOLCAP Project realized within the WELCOME Program, co-financed from European Union Regional Development Fund.

Electrical Conductivity in Dimethyl Sulfoxide + Potassium Iodide Solutions at Different Concentrations and Temperatures

The direct current conductivity of DMSO + KI solutions was determined with the use of the impedance spectroscopy. The measurements were performed in the whole solubility range of KI and in the temperature range from (293.15 to 323.15) K. The limiting molar conductivities Λo(T) and λI–o(T), as well as the constant KA of ionic association, K+ + I–, were determined at different temperatures with the use of the Fuoss-Onsager method. The obtained data on KA, together with the literature data referred to the K+ + I– association in different solvents, allowed us to formulate an empirical dependence of KA on the molecular dipolar polarizability of the solvent used, KA ∝ exp(−μi2), where μi is the dipole moment of the molecules of ith solvent.

Modification of silver iodide particles caused by a flow of electrons

A crystalline powder of AgI has been synthesized using an exchange reaction of aqueous solutions of AgNO3 and KI. The size and shape of the crystals are determined with the help of scanning electron microscopy. It is shown that nanocrystalline silver particles (30–70 nm) are formed at the surface of monocrystalline AgI particles (500–2000 nm) under the action of a focused bunch of electrons.

Crystal structure of cis-diiodidobis(quinoline-κN)platinum(II), C18H14I2N2Pt

Abstract C18H14I2N2Pt, monoclinic, C2/c (no. 15), a = 18.803(1) Å, b = 9.1761(5) Å, c = 11.6537(7) Å, β = 112.260(1)°, V = 1860.9 Å3, Z = 4, Rgt(F) = 0.0307, wRref(F2) = 0.0685, T = 200 K.

Equilibrium swelling of some poly(N-IPAAm-sulfobetaine) hydrogels in water and in aqueous solutions of a single salt

The influence of single salts (either NaCl, K2CO3, KI, KSCN, KF and Na2SO4) on the degree of swelling of some copolymeric hydrogels of N-isopropyl acrylamide (N-IPAAm) and a zwitterionic comonomer sulfobetaine (=[3-(methacryloylamino) propyl] dimethyl (3-sulfopropyl) ammonium hydroxide inner salt (MPSA)) in water at 298K was investigated experimentally. As expected, the experimental results reveal that at low salt concentrations (mass fractions of salt in aqueous solution below about 10−3) none of the investigated salts has an influence on the degree of swelling. As also expected, at high salt concentrations (mass fraction above ≈10−1) the gels collapse. However, an increase of the degree of swelling at intermediate salt concentrations was found for all investigated gels in aqueous solutions of either KSCN or KI as well as for the gels with a high content of sulfobetaine in aqueous solutions of NaCl. This phenomenon is called “anti-polyelectrolyte” behavior.A previously developed thermodynamic model was extended to describe (i.e., correlate and predict) the experimental results for the swelling behavior. Calculation results for the degree of swelling are in good agreement with experimental data. In most cases the difference between the experimental and the calculation result for the degree of swelling is lower than the corresponding experimental uncertainty.

New approach to electrochemical iodination of arenes exemplified by the synthesis of 4-iodopyrazoles of different structures

The two-stage electrosynthesis of 4-iodosubstituted pyrazole derivatives was performed. At the first stage, KIO3 was obtained at the Ni anode under the undivided galvanostatic conditions of electrolysis of an aqueous alkaline solution of KI (or I2) at the Ni anode. At the second stage, pyrazole and its derivatives were iodinated in the heterophase (H2O-CHCl3 (CCl4)) medium by the KIO3-KI (or KIO3-I2) system in the presence of H2SO4. The yields of iodopyrazoles were 74–92%. The electrochemical iodination of anisole, 2-methylpyrazole, and thiophene was carried out to form 4-iodoanisole (88% yield), 4,5-diiodo-2-methylimidazole (54% yield), and a mixture of 2-iodothiophene (60% yield) and 2,5-diiodothiophene (4% yield).

Iodine‐enhanced micro‐CT imaging: Methodological refinements for the study of the soft‐tissue anatomy of post‐embryonic vertebrates

The now widespread use of non-destructive X-ray computed tomography (CT) and micro-CT (µCT) has greatly augmented our ability to comprehensively detail and quantify the internal hard-tissue anatomy of vertebrates. However, the utility of X-ray imaging for gaining similar insights into vertebrate soft-tissue anatomy has yet to be fully realized due to the naturally low X-ray absorption of non-mineralized tissues. In this study, we show how a wide diversity of soft-tissue structures within the vertebrate head-including muscles, glands, fat deposits, perichondria, dural venous sinuses, white and gray matter of the brain, as well as cranial nerves and associated ganglia-can be rapidly visualized in their natural relationships with extraordinary levels of detail using iodine-enhanced (i-e) µCT imaging. To date, Lugol's iodine solution (I2 KI) has been used as a contrast agent for µCT imaging of small invertebrates, vertebrate embryos, and certain isolated parts of larger, post-embryonic vertebrates. These previous studies have all yielded promising results, but visualization of soft tissues in smaller invertebrate and embryonic vertebrate specimens has generally been more complete than that for larger, post-embryonic vertebrates. Our research builds on these previous studies by using high-energy µCT together with more highly concentrated I2 KI solutions and longer staining times to optimize the imaging and differentiation of soft tissues within the heads of post-embryonic archosaurs (Alligator mississippiensis and Dromaius novaehollandiae). We systematically quantify the intensities of tissue staining, demonstrate the range of anatomical structures that can be visualized, and generate a partial three-dimensional reconstruction of alligator cephalic soft-tissue anatomy.

Effect of interphase interaction on ion transport in nanosytems based on AgI and ZnO

The effect of interphase interaction on ion transport in nanodisperse composite materials is studied by the example of the ZnO-AgI system. Ion-conducting films of composition 0.7AgI-0.3ZnO are obtained by laser ablation. Fine-crystalline AgI powder prepared by the exchange reaction of aqueous solutions of AgNO3 and KI is used as the initial material. The surface morphology of prepared samples is studied by scanning electron microscopy. Their conductivity is measured by impedance spectroscopy. The elemental composition of prepared films is determined by X-ray microprobe analysis. Phase composition is established by X-ray diffractometry. The conductivity of 0.7AgI-0.3ZnO films and pressed cylindrical samples of fine-crystalline AgI powder 5 mm in diameter and 2 mm in height with ends coated with graphite contacts is measured.

Application of phase-transfer catalytic membrane reactor in liquid–liquid nucleophilic substitution reaction: Effects of operating parameters

Porous polyethylene membranes were modified by γ-ray irradiation grafting of 4-vinyl pyridine and then quaternization to obtain phase-transfer catalytic membranes. The catalytic membranes were employed in liquid–liquid nucleophilic reactions between n-bromooctane and KI aqueous solution. The analysis of the membrane reactor and the plausible phase-transfer catalytic mechanism were given. The effects of concentrations of n-bromooctane and KI, flow rates of KI and organic solutions, and catalytic group structure were investigated. It was found that, the batch-recycle membrane reactor can be regarded as a differential reactor. The observed reaction rate constant rises with the increase in KI concentration, flow rates of KI and organic solutions, alkyl chain length of catalytic group. The TOF of catalytic membranes is much higher than that of quaternized poly(4-vinyl pyridine) powder. Mass transfer cannot be neglected under the experimental conditions.

NaCl and KCl phase diagrams of kappa/iota-hybrid carrageenans extracted from Mastocarpus stellatus

The phase diagrams of kappa/iota-hybrid carrageenan (KI) in KCl and NaCl are reported for the first time, together with the large strain properties of obtained KI gels. KI shows salt specificity as phase diagrams in KCl and NaCl are different. These diagrams do not comply with those of a mixture of kappa- and iota-carrageenan (K + I). Concentrated KI solutions in NaCl up to 0.3 mol/L exhibit viscoelastic properties reminiscent from entangled neutral polymers with no aggregation. Both KI and K + I gels are strain hardening, and show a concentration scaling of the elasticity with exponents ranging from 1.2 to 3.2 depending on the type of salt and ionic strength. The strain at break of KI gels does not show salt specificity in contrast to K + I gels. In NaCl, KI gels are less brittle than K + I gels. In KCl, KI gels show the same level of strain at break as the corresponding carrageenan mixture.

Optimization of Activated Carbon Sulfurization to Reach Adsorbent with the Highest Capacity for Mercury Adsorption

This work deals with the use of elemental sulfur immobilized on the activated carbon surface, as an active phase to enhance the sorbent's mercury adsorption capacity. The sulfurization procedure was optimized, and the influence of two factors (temperature and initial ratio of sulfur to carbon), on the final properties and mercury adsorption capacities of the adsorbents was investigated. The sulfurized adsorbents were characterized using CHNS/O elemental analysis, surface area and porosimetry, FT-IR spectroscopy, SEM-EDS, and pHpzc measurement. A series of batch studies were also conducted to delineate the effect of contact time, initial pH, solution temperature, and initial mercury concentration on the adsorption capacity of the adsorbents. Furthermore, attempts were made to desorb mercury from the metal loaded adsorbents using various concentrations of KCl, KBr and KI solutions.

Hydration numbers of ions in aqueous solutions of KOH, KCl, KI, and KIO3 according to refractometric data

Ion hydration in aqueous solutions of KOH, KCl, KI, and KIO3 was studied by refractometry. The sum of the hydration numbers of the potassium ion and each anion in these compounds and the hydration numbers of OH−, Cl−, I−, and IO3− anions were determined by the Lorentz-Lorenz equation at different salt concentrations. The model suggests that the polarizability of the hydrated ion is proportional to the cube of the ion radius and the volume of the hydrated ion equals the sum of the nonhydated ion and hydration shell volumes. The hydration numbers of the anions calculated by the proposed procedure increase with their radii in the sequence: OH−, Cl−, I−, and IO3−.

Verification of Solvation Theory of Dilute to Concentrated Solutions of Some Strong 1–1 Electrolytes

Density, ultrasonic velocity and isobaric heat capacity data have been used to study solvation parameters of aqueous solutions of NaCl, NaNO3, and KI. Using correct thermodynamic relations, quantitative solvation parameters have been determined at temperatures from 278.15 to 323.15 K: the hydration numbers h, the molar isentropic compressibilities of the solvation complexes $$ \beta_{S,h} V_{h} , $$ the volume V 1h , the coefficient of isentropic compressibility β 1h of water in the solvation shells of ions, and others. It has been shown that h is independent of the temperature in the range of the investigated conditions, $$ \beta_{S,h} V_{h} $$ is dependent both on the temperature and concentration, whereas the electrostriction compression in the vicinity of ions has a greater effect on its structure than that due to the mere change of pressure.

Influence Coefficients of Stress Intensity Factors for Curved Tubing With a Semi-Elliptical Crack

The boundary element method is employed to determine polynomial influence coefficients of stress intensity factors, KI, for a semi-elliptical crack in internally pressurized thick-walled curved tubing. Numerical results of these coefficients are obtained for a wide range of geometric parameters; they are the bend radius ratio, cross-sectional radius ratio, angular extent of the bend, and relative crack depth. The use of influence coefficients allows KI solutions to be determined for different load cases without repetitive 3D stress analysis of the cracked body. This is demonstrated for the case of autofrettage where the effects on KI of the residual stresses arising from it are presented.

Synthesis of alumina impregnated with potassium iodide catalyst for biodiesel production from rice bran oil

In this work, a catalyst based on alumina impregnated with potassium iodide was synthesized and tested in the process of transesterification of rice bran oil with methanol. The reaction took place in a reflux system, with a molar ratio of 15:1 methanol:oil. The catalyst was prepared by impregnation of alumina with a solution of KI followed by calcination at 773K for 3h. The effect of concentration of the catalyst in the yield was verified in the range of 1–5wt.%, and the properties of specific gravity and kinematic viscosity of the biodiesel were determined. The increasing of the yield of the reaction was observed for high amount of catalyst. When 5wt.% of the catalyst was used in the process, the best results was obtained, with 95.2% yield. As expected, the specific gravity and kinematic viscosity decreased with the catalyst amount. From TG analysis, it was observed a mass loss of 96.2%, evidencing the high activity of the catalyst for the process.

Equilibrium interfacial tension and the influence of extreme dilutions of uni-univalent salts: An expression of the “Jones–Ray effect”

There are inevitable low levels of salt content in qualified waters which can alter accurate estimations of water interfacial tension with organic immiscible liquids. In this study, the equilibrium interfacial tension variation of extremely diluted (0.001mmol·dm−3 to 0.050mmol·dm−3) aqueous solutions of NaCl, KCl and KI, and toluene at different temperatures of (20.0 to 50.0)°C was studied. Measurements were performed by the drop-weight method. Interfacial tension becomes reduced by (0.41 to 0.86)mN·m−1 at the highest salt concentrations used and different temperatures. A linear decrease in this parameter was also observed with increasing temperature. The order of this salt effect on the interfacial tension follows: KI>KCl≈NaCl at all temperatures except 50.0°C where KCl has a stronger effect than NaCl. Assuming that inorganic ions do not penetrate the non-polar organic phase, the Petersen–Saykally model for surface tension which predicts the descending trend of variations and is based on the well-known “Jones–Ray effect” was used for modelling the data provided. Good agreement was found with three adjustable parameters for each salt and temperature.