Aqueous Solutions Of KI Research Articles

Comments on the mechanism of microbial cell disruption in high-pressure and high-speed devices

The dominant mechanism for microbial cell disruption in a high-pressure homogenizer and a high-speed homogenizer used in this study has been identified. It was found that the cavity collapse and the pressure pulse resulting from such a collapse have a significant influence on the rates of cell disruption. The similarities among the operating conditions for the decomposition of the aqueous KI solution to liberate iodine, the reaction occurring only under cavitating conditions, and that required for the substantial disruption of microbial cells have been pointed out. The liberation of iodine by the aqueous KI decomposition is treated as evidence of cavitation, and hence microbial cell disruption occurring at an identical discharge pressure confirms the mechanism of cell disruption as cavitation, in the high-pressure homogenizer valve. In the case of the high-speed homogenizer, shear and cavitation both play a significant role in cell disruption.

A Channel-Forming Polyiodide Network in [Cu(dafone)3]I12. A Tris Chelate of Dafone and a New Planar Structure for the I122- Ion (Dafone = 4,5-Diazafluoren-9-one)

Treatment of an aqueous solution of copper(II) acetate, dafone, and KI with I2 in CH2Cl2 leads to the formation of Cu(dafone)3I12 (1). 1 crystallizes in the orthorhombic system, space group Pbcn, with a = 22.902(4) Å, b = 11.104(2) Å, c = 18.992(7) Å, and Z = 4. Cu(dafone)32+ is the first tris chelate of dafone and is stabilized by a channel-forming network of planar I122- ions. Temperature dependence of the EPR spectrum indicates fluxionality of the cation.

Effects of ultrasound on the electrolytic conductivity of simple halide salts

Ultrasound irradiation of aqueous solutions of KCl, LiCl and KI causes an increase in their conductivity (measured with AC at 1000 Hz), which disappear as soon as ultrasound irradiation is switched off. The phenomenon is explained in terms of collapse of cavitational bubbles created by ultrasound in the solution with release of energy under the form of shock waves and heat.

Hybrid Electrochemical/Chemical Synthesis of Supported, Luminescent Semiconductor Nanocrystallites with Size Selectivity: Copper(I) Iodide

β-CuI nanocrystallites (NCs) are synthesized on the atomically smooth graphite basal plane surface using a new hybrid electrochemical/chemical (E/C) method. This method involves the following steps: (1) electrochemical deposition of copper NCs onto an electrode surface, (2) electrochemical oxidation of these copper NCs to yield Cu2O, and (3) displacement of oxygen in Cu2O by iodide in an aqueous KI solution. Dispersions of CuI NCs having mean diameters ranging from 10 to 180 Å were prepared using the E/C method. Selected-area electron diffraction analysis reveals that β-CuI NCs are obtained; these NCs are epitaxially aligned with the hexagonal periodicity of the graphite surface, as are the Cu2O precursor particles. For samples of supported CuI NCs having a mean particle height of <25 Å, individual NCs were well-separated from one another on the graphite surface and were narrowly dispersed in height. Photoluminescence spectroscopic analysis showed a strong, room temperature emission at an energy corresponding to the band gap. As the crystallite diameter was reduced from 180 Å to 13 Å, the energy of this emission shifted from the macroscopic value of 2.92 eV to >3.04 eV, in good agreement with the predictions of the effective mass, strong confinement model.

Mass transfer coefficients in mixer-settler extraction column.

The volumetric over-all mass transfer coefficient K c a and the volumetric dispersed phase mass transfer coefficient k d a in a mixer-settler extraction column were measured. In the measurement of K c a, iodine was extracted from I 2 -KI aqueous solution into heptane, while iodine was back-extracted from a heptane solution of iodine into sodium thiosulfate aqueous solution to obtain k d a. By using specific interfacial area determined from the estimated Sauter mean diameter of the dispersed drops and the estimated holdup of the dispersed phase, the mass transfer coefficients for the dispersed and the continuous phases were determined from the volumetric coefficients K c a and k d a. The coefficient k d for the dispersed phase coincided with the theoretical value based on diffusion within a rigid sphere using the residence time distribution of dispersed drops. On the other hand, the coefficient k c for the continuous phase agreed well with the correlation of mass transfer around a rigid sphere by assuming that the relative velocity of the dispersed drop to the continuous phase was given by the terminal settling velocity of a rigid sphere having the same diameter and density as the drop.

Structure of iodine—nylon 6 complex: 4. Irregular stacking of intercalated iodine in the complex

Oriented iodine-doped nylon 6 specimen which was prepared in an I 2KI aqueous solution was immersed into a KI aqueous solution. The ‘re-immersed’ specimen indicated an irregular intercalation of iodine stacked between hydrogen-bonded planes of nylon 6 in the complex. In the irregular stacking, iodine atoms or polyiodides are not intercalated between all of the interlayer region, while they are between each hydrogen-bonded plane of nylon 6 chains in ordinary complex; spacing of the planes is 1.95 nm in the irregular intercalation while it is 1.56 nm in the ordinary specimens. In the complex with the irregular stacking, however, the ordering along the chain axis is similar to the ordinary one. This irregular structure is induced by applying an inhibitive effect of the I − ion to prevent doping in the I 2KI aqueous solution. It suggests that the iodine—nylon 6 complex can introduce various intercalated structures such as graphite intercalation compounds.

Spectroscopic and electrochemical study of conducting films of tetrathiotetracene iodides

Films of tetrathiotetracene (TTT) iodides were prepared by electrochemical doping of deposited TTT films and were subjected to manyfold cycling in 0.2 mol L−1 aqueous KI solution in the range of potentials from +0.04 to +0.34 V relative to Ag/AgCl. The thus formed films were electrochromic: their color changed reversibly as the potential changed. The results of spectral and electrochemical studies show that radical-cation salts of (TTT)Ix type are accounted for by the presence of several forms of such salts that differ in the content of iodine and reversibly transform into each other with potential changes. The formal compositions of the salts formed under high and low potentials can be approximately described as (TTT)I0.9 and (TTT)I0.5, correspondingly.

Mass spectrometric calibration of an atomizer/nebulizer for doping flames or discharge plasmas

An atomizer or nebulizer provides a very versatile means of doping a flame or discharge plasma with a small amount (typically < 10 −5 mole fraction) of an additive. A wide variety of substances (e.g. salts of metallic halides) can be introduced as an aerosol by spraying an aqueous solution into the system, but the additive concentration must be calibrated. Optical calibration methods are difficult, and measurements of the atomizer effluent or depletion are unreliable. A conceptually simple and general method has been developed for calibration of the atomizer concentration in situ when the system can be sampled by a mass spectrometer. A solution is sprayed with the atomizer, which produces a distinctive type of ions in the system, either positive or negative. The same type of ions is then produced by introducing the vapour of a volatile substance of known vapour pressure using a small flow of a carrier gas through a gas saturator. By varying the saturator flow rate, the ion signal from the saturator is then matched to the ion signal from the atomizer. As the concentration introduced by the saturator is known, the calibration factor for the atomizer can be determined. An example is worked out for a premixed H 2O 2Ar flame having essentially no natural ionization, which is doped with an atomizer spraying a 0.05 M aqueous solution of KI to produce K + and I −. Then, with the atomizer spraying a 0.05 M KNO 3 solution, the I − atomizer signal is matched by an I − signal produced when C 6H 5I vapour is introduced by a tiny flow rate of argon through the saturator. If the ion chemistry is straightforward, the mass spectrometer could be replaced by a total ion collector. The method should be applicable to a variety of flames and also to discharge plasmas.

Interfacial structure of iodine electrodeposited on Au(111): studies by LEED and in situ STM

Iodine adlayers formed on Au(111) in aqueous KI solution have been studied by ex situ Auger electron spectroscopy (AES), low-energy electron diffraction (LEED) and in situ scanning tunneling microscopy (STM). The LEED patterns are described as c ( p × 3 R − 30 ° ) where p decreases continuously with increasing emersion potential. By in situ STM, a series of rotated hexagonal structures was observed at positive potentials in addition to the c ( p × 3 R − 30 ° ) structures. This rotated hexagonal adlattice was also compressed with increasing electrode potential. These results in general confirm the phenomenon of electrocompression of the iodine adlayer on Au(111) observed by in situ surface X-ray scattering.

Modelling of a batch sonochemical reactor

Ultrasonication of aqueous KI solution is known to yield I 2 due to reaction of iodide ions with hydroxyl radicals, which in turn are generated due to cavitation. Based on this conceptual framework, a model has been developed to predict the rate of iodine formation for KI solutions of various concentrations under different gas atmospheres. The model follows the growth and collapse of a gas—vapour cavity using the Rayleigh—Plesset bubble dynamics equation. The bubble is assumed to behave isothermally during its growth phase and a part of the collapse phase. Thereafter it is assumed to collapse adiabatically, yielding high temperatures and pressures. Thermodynamic equilibrium is assumed in the bubble at the end of collapse phase. The contents of the bubble are assumed to mix with the liquid, and the reactor contents are assumed to be well stirred. The model has been verified by conducting experiments with KI solutions of different concentrations and using different gas atmospheres. The model not only explains these results but also the existence of a maximum when ArO 2 mixtures of different compositions are employed.

USE OF POTASSIUM IODIDE AS A CHEMICAL ACTINOMETER

Aqueous solutions of KI were examined for use as chemical actinometers to measure 254 nm (germicidal) radiation. Irradiation results in electron ejection from iodide such that aqueous electrons and iodine atoms are formed. In the presence of N2O, an electron scavenger, recombination of these two reactive species is eliminated and stoichiometric formation of triiodide occurs. The absorbance increase due to triiodide was followed and the quantum yield determined using either a radiometer or ferrioxalate actinometry to estimate the amount of energy absorbed by the KI solution. The quantum yield (phi) at 25 degrees C was determined to be 0.26 using radiometry, and 0.224-0.233 using actinometry, depending on the radiation conditions. The following expression was used to measure the incident fluence rate for 254 radiation at a given temperature T for irradiation over a time interval delta t (s) [formula: see text] At temperatures other than 25 degrees C, the temperature dependence of the quantum yield (0.004/degrees C) is taken into account by the term shown in the denominator. Because KI remains relatively blind to longer wavelengths such as those found in normal room light, measurements can be made in the presence of room light without having to work in a darkened room.

Thermodynamic properties of aqueous electrolyte solutions. 2. Vapor pressure of aqueous solutions of sodium bromide, sodium iodide, potassium chloride, potassium bromide, potassium iodide, rubidium chloride, cesium chloride, cesium bromide, cesium iodide, magnesium chloride, calcium chloride, calcium bromide, calcium iodide, strontium chloride, strontium bromide, strontium iodide, barium chloride, and barium bromide

A differential static method was used for the measurement of vapor pressures of aqueous solutions of NaBr, NaI, KCl, KBr, KI, RbCl, CsCl, CsBr, CsI, MgCl 2 , CaCl 2 , CaBr 2 , CaI 2 , SrCl 2 , SrBr 2 , SrI 2 , BaCl 2 , and BaBr 2 from 0.5 to 8.6 m and in the temperature range of 303.15-343.15 K. The experimental data for the binary solutions were fitted to the Antoine type of equation. Vapor pressure data were used to calculate activity and osmotic coefficients in the temperature range studied for understanding the nonideal behavior of these solutions

The structure‐breaking effect on oxygen diffusion coefficients in electrolyte and polyelectrolyte solutions

AbstractBy employing a membrane‐covered polarographic oxygen electrode, the oxygen diffusion coefficients and solubilities in aqueous solutions of ammonium chloride, potassium iodide, sodium alginate, sodium carboxymethylcellulose (CMC), and xanthan gum have been measured with a newly developed methodology. Experimental results showed that in all systems studied, oxygen solubilities decrease on addition of solutes. Oxygen diffusion coefficients in aqueous solutions of KI and NH4C1 are found to be higher than that in pure water. In sodium alginate solutions, dilute xanthan solutions, and solutions containing more than 0.3 wt% of CMC, oxygen diffusion coefficients decrease with an increase in polymer concentrations. Interestingly, in dilute CMC solutions and concentrated xanthan solutions containing more than 0.5 wt% of xanthan gum, oxygen diffusion coefficients increase with increasing polymer concentrations, and values exceeding that in pure water are generally observed.

The effect of background on the protonation of pyridine: a complex formation model

The protonation constants of pyridine were obtained in aqueous solutions of LiCl, NaCl, NaClO 4, NaNO 3, NaI, KNO 3, KI, RbCl, CsCl, MgCl 2, CaCl 2, tetramethylammonium iodide, tetraethylammonium iodide, tetramethylammonium chloride and tetraethylammonium chloride in the ranges 0 ⩽ I ⩽ 1 mol] −1 and 10 ⩽ T ⩽ 45 ° C. The differences in the protonation thermodynamic parameters of pyridine in the various solutions were interpreted in terms of weak species formation between the components.

ChemInform Abstract: The Photocatalytic Oxidation of Iodide Ions by Titanium Dioxide

Abstractis investigated in 0.1 M neutral aqueous KI solutions using suspensions of pure anatase and rutile, 5 doped rutiles (0.1 mol% Cr2O3, Fe2O3, NiO, Nb2O5, or WO3) and 2 commercial anatase pigments as catalysts.

Photoelectrochemical behavior of Cu 2O single crystals in liquid electrolytes

Photoelectrochemical behavior of single crystalline Cu 2O electrodes in aqueous solutions of KI and CH 3OH has been studied using a simple cell with three electrodes. Most of the Cu 2O electrodes showed a broad peak in their spectral response of the photocurrent in the visible region centered at around 595 nm (2.08 eV). However, the Cu 2O electrodes were not stable in the liquid electrolytes. It can be concluded from the results that the chemical reaction of Cu 2O with the electrolytes is depressed by O 2 gas as compared to N 2 gas bubbling in the system.

Structure of coals studied by iodine and water adsorption

Vitrinite in coal is considered as a macromolecular system exhibiting intermolecular microporosity. The surface of this microporosity reflects the structures of the macromolecular system. Adsorption of nitrogen and carbon dioxide provide micropore volumes; adsorption of water and ammonia respond to surface polarity; adsorption of iodine responds to electron availability to form charge transfer complexes. Iodine was adsorbed, both from the vapour phase and aqueous KI solution, by a rank range of coals, fresh, oxidized and pyrolysed. Extents of iodine adsorption were greater from aqueous solution and increased with increasing coal rank to about 87wt% C and then decreased. Extents decreased with increasing severity of oxidation from both vapour and aqueous phases; extents of iodine adsorption increased with increasing heat treatment temperature of coal pyrolysis to decrease subsequently on charring and coking. Results are interpreted in terms of aromaticity of coals, the extent of cross-linkage, and mechanisms of oxidation and pyrolysis.

EVALUATION OF GAS PHASE MASS TRANSFER AT LOW REYNOLDS NUMBERS: A NEW MODEL SYSTEM

A new experimental system is presented which is suitable for studying gas side mass transfer coefficients in packed columns at Reynolds numbers even lower than 1·0. The system involves desorption of iodine from aqueous KI solutions. The reversible complex formation between iodine and iodine ions effectively slows down the concentration changes which otherwise would be too rapid for accurate experimentation.

Adsorption properties of gamma-irradiated carbons

Steam-activated carbon specimens (OL) were subjected to different doses of γ-irradiation varying between 7 and 100 Mrad. The adsorption of iodine from aqueous KI solution at 25°C, nitrogen at -196°C and carbon dioxide at 25°C were carried out. The results revealed that γ-irradiation uo to 35 Mrad did not lead to any detectable change in the adsorption behaviour of the adsorbates investigated. However, irradiation at higher doses viz. 80 and 100 Mrad resulted in a significant increase in pore size as determined from carbon dioxide adsorption isotherms to an extent proportional to the dose employed. This increase might be attributed to a possible radiolytic decomposition of oxygen complexes located on the surfaces of stream-activated carbons. Observed change was also found in the shape of iodine isotherms. However, a single nitrogen isotherm was measured for both the unirradiated and all irradiated carbons.

Ionic components of charge at the mercury-KCl +KI aqueous solution interphase

The ionic components of charge for the mercury aqueous mixtures of KI + KCl interphase have been obtained from capacitance measurements. The experimental results show that the Cl − ion is not specifically adsorbed in the concentration range studied. The specifically adsorbed charge of the iodide ion was obtained by two methods. Grahame's using the Gouy Chapman theory, σ 1 I − (GC) and the method of Parsons—Hurwitz, σ 1 I − (PH). The differences between the two sets is analyzed in terms of the assumptions made in their calculation. The σ 1 I − (GC) shows a crossing point at high σ in the σ 1 I − - vs σ plot. It is explained in terms of an increase in the amount of water at the compact layer and an increase in the amount of iodide ion at the diffuse layer. Other features of the σ 1 I − (GC) vs σ curves are explained in terms of errors of the simple Gouy Chapman model.