KI Solutions Research Articles

Evaluation of chemical desiccation as a selection technique for drought resistance in a dryland wheat breeding program

Previous studies have shown that some chemical desiccants and senescing agents, when applied to adequately watered cereals 10 to 14 days after anthesis, can be used to select lines with stable grain size (kernel weight) under post-anthesis water deficits. The present study evaluated the potential of one of these chemicals, potassium iodide (KI), to select for this character in a dryland wheat breeding program. Ninety-six F2-derived lines grown in the F6and F7 generations and 11 cultivars of wheat (Triticum aestzvum L.) were grown in two experiments at two medium-rainfall sites in 1988 and 1989 and sprayed with a 0.3% solution of KI when the grains had developed one-third in the lemma. Reductions in grain yield and thousand kernel weight due to treatment with KI were greater in 1988 than in 1989, probably due to the higher growing-season rainfall in that year. The reduction in grain yield as a result of desiccation was greater than the reduction in thousand kernel weight, but the correlation between the two was low (0.09 to 0.58) and non-significant in five out of the eight comparisons. There were considerable differences among genotypes in response to the desiccation treatment in the wetter 1988. Genetic coefficients of variation ranged from 5.6 to 12.9% for yield and 2.5 to 9.5% for thousand kernel weight. The ratio of the variance component estimates for the interaction between genotypes and desiccation treatment to the variance component estimates for genotypes was generally less than one. However, genetic differences in response to the desiccation treatment could be demonstrated in some experiments, particularly at one site and in the wetter of the two years. We conclude that the chemical desiccation technique can be used to select for post-anthesis drought resistance in a dryland breeding program. However, there are some limitations to the technique, and selection needs to be confined to wetter sites and seasons.

Mechanism of Starch Gelatinization in Neutral Salt Solutions

AbstractDSC thermograms showed that salt affected the onset temperature (T0) and enthalpy change (AH) of starch gelatinization and that the effect differed by type of salt and concentration. Anion effects seemed to parallel the structure‐making and structure‐breaking effects of water. At all concentrations, sulfate ions increased T0 and AH, but thiocyanate suppressed them. T0 and AH were affected by cations in a complex mode. In CaCl2 (3molal) or LiCl (7–10m) solution, starch gelatinized at room temperature but did not gelatinize in NaCl or KCI solutions at any concentration. Light micrographs taken at room temperature showed that in KSCN and KI solutions (>2m) starch gelatinization began at the hilum but in CaCl2 (3m) and LiCl solutions (7–10m) starch gelatinization started at the periphery. It was concluded that the mechanism of starch gelatinization in salt solutions can be attributed to: (1) structure‐making and structure‐breaking effects on water and (2) electrostatic interactions between salts and hydroxyl groups of starch.

Solidification of Iodide Ion by Reaction with Bi2O3

Abstract α-Bi2O3 is a candidate material for the immobilization of radioactive iodine. The present paper discusses a method for removing radioactive iodide ion by fixing it into α-Bi5IO7 by a direct reaction with α-Bi2O3; it also reports on experimental conditions under which aqueous iodide reacts with α-Bi2O3 to form a single phase of α-Bi5IO7. α-Bi2O3 was reacted with aqueous iodide in LiI, NaI, KI, and NH4I solutions. Although a previous paper reported that the concentration of aqueous iodide ion was the most important factor to form a single phase of α-Bi5IO7, the present result shows that it is not an important factor. The α-Bi5IO7 single phase can be obtained regardless of the concentration of iodide ion when the ratio of the gram molecular number of the bismuth oxide and the gram ion number of the radioactive iodide ion is adjusted in the range 5 : 2 to 1 : 2 in a LiI solution, 4 : 1 to 1 : 2 in a NaI solution, and 4 : 1 to 1 : 4 in a KI solution. A reaction in a NH4I solution does not produce a single phase of Bi5IO7 at any ratio.

The enthalpic interaction parameters of Nacl, KCl and KI with acetone in water at 298.15 K

The enthalpies of solution of NaCl, KC1 and KI have been measured in water and in mixtures of acetone with water at 298.15 K. The enthalpic interaction parameters h xy, h xxy and h xyy of the three salts with acetone have been evaluated. The dependences of the enthalpic interaction parameters on the ionic size of the electrolyte have been discussed with respect to the electrostatic interaction and structural interaction.

Single-ion transfer enthalpies in methanol-acetonitrile mixtures at 298.15 K based on the Ph 4P + = BPh 4− assumption

The enthalpies of solution of KI, NaBPh 4 and Ph 4PI in methanol-acetonitrile mixtures were measured at 298.15 K. From these data, together with those for NaI taken from our earlier work, and with literature data that refer to ( n-Bu) 4NBr, ( n-Bu) 4NI and ( n-Bu) 4ClO 4, the enthalpies of transfer of the individual ions Ph 4P +, BPh − 4, Na +, K +, Br −, I −, ClO 4 − and ( n-Bu) 4N + from methanol to acetonitrile-methanol mixtures were calculated employing the assumption Δ H t XXX(Ph 4P +) = Δ H t XXX(BPh − 4).

An alternative to halogenated solvents for halogen/halide extractions

The equilibrium is established by dissolving iodine in a solution of KI of known concentration. The total I2 and 13concentration a t equilihrium is determined by titrating the aqueous solution with thiosulfate (2). The solution is then extracted with carbon tetrachloride, and the I2 concentration in the nonpolar solvent is determined by titration with thiosulfate. The equilibrium concentration of 12 in the aqueous solution can he calculated from the I? concentration in the nonpolar solvent and the distribution coefficient for the extraction of iodine between CCla and water.

Enthalpies of solution of glycine in aqueous electrolyte solutions at 298.15 K

The enthalpies of dissolution of glycine in aqueous 0.5, 1.0, 1.5, 2.0 and 2.5 mol kg −1 H 2O solutions of NaCl, KC1, CsCl, Nal, KI, Csl, NaNO 3 and KNO 3 were measured at 298.15 K. The glycine molecule-electrolyte enthalpic pair interaction coefficients were determined using standard solution enthalpies of glycine in water and aqueous solutions of electrolytes.

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

Gold dissolution in iodide electrolytes

Several oxidants (hypochlorite, iodine and hydrogen peroxide) were used to evaluate the dissolution of gold in iodide electrolytes at ambient temperatures. Evans diagrams constructed for the two half cells involved in the dissolution process show that hydrogen peroxide is not a suitable oxidant for the iodide system. The gold dissolution rate in an iodine-iodide mixture is dependent upon the concentration of iodide, iodine and the solution pH. An optimum iodine-iodide mole ratio of 0.35–0.4 was found for 0.1 M KI solutions, with pH ranging from 2.7 to 11.5; these are capable of dissolving gold at a maximum rate of 17 mg/cm 2h. If a small addition of hypochlorite is made (< mM for 0.1 M KI solutions), gold will be dissolved faster than with iodine as oxidant. However, the gold dissolution rate in a hypochlorite-iodide mixture is strongly dependent upon the solution pH. The optimum hypochlorite-iodide mole ratio is 0.25 for KI solutions of 0.02 to 0.1 M at pH 2.7. Cyanidation, using the same concentration of cyanide yielded gold dissolution rates within the range of 1.3 (at pH 12.5) and 3.5 mg/cm 2h (at pH 8.5).

Influence of disperoids on the transport behaviour of Ag2HgI4

The basic research on solid electrolytes was bifurcated into a search for new compounds that exhibit very high ionic conductivity at ambient temperature and to modify the properties of known materials as viable electrolytes at ambient temperature. The heterogeneous doping technique is used in the second category where the transport properties of an ionic solid can be modified by the dispersion of insoluble and insulating oxides as a second phase. Stimulated by the success of two orders of enhancement in the electrical conductivity of LiI by the dispersion of fine alumina particles [1], several other successful experimental results were reported (see [2-4] and references in [3, 4]). Eventually these dispersed solid electrolytes have attracted a great deal of attention to both experimental and theoretical researchers to understand the mechanism of enhancement in electrical conductivity of the host ionic solid. Silver tetra-iodomercurate is one of the earliestknown silver-ion conductors which possesses high silver-ion conduction only in the ol-phase above 60 °C. At ambient temperature it is a poor ionic conductor [5]. Hence, this study aimed at enhancing the ambient temperature conductivity of AgzHgI4, since it has been successful with its two constituents AgI [2] and HgI2 [6]. A new method of preparing these heterogeneous solid electrolytes was adapted and the validity of the method was tested on AgI electrolytes with various dispersoids, which is also correlated with a different documented method of preparation. The present investigation dealt with the discussion of experimental results on the influence of various dispersoids on the conduction characteristics of Ag2HgI4 in the low-conducting fiand highconducting 0l-phases. The compound AgI was precipitated from KI and AgNO3 (AR grade, BDH, UK) solutions followed by drying at 110 ° for 48 h under an inert atmosphere. Various insulating oxides of different particle sizes, 7-A1203 (0.06/~m), y-AI20 3 (1.0/~m) and SiO2 (0.007/~m) from Meller Company and polishing alumina (about 1.0/~m) from Geologists Syndicate, India were dispersed in the AgI matrix, by dispersing them in AgNO3 solution before precipitating AgI. Thus, the composite electrolytes ( 1 x) AgI-x dispersoid for 0 < x < 40 mol % (wt % in the case of polishing A1203) were precipitated and dried under vacuum at 110 °C for 48 h. In an earlier report [2] these AgI composite electrolytes were prepared by melting appropriate quantities of AgI and dispersoid under vacuum, followed by slow quenching. The compound AgzHgI 4 was synthesized from

Electrochemical formation of bismuth oxyhalide films in neutral halide solutions

The processes of anodic oxidation of bismuth in neutral aqueous halide solutions have been investigated. It has been found by X-ray diffraction analysis that in KCl, KBr and KI solutions, porous polycrystalline anodic bismuth oxyhalide (BiOHal) films are formed on the bismuth electrode, while in KF solutions, a bismuth trifluoride (BiF 3) film with an admixture of tysonite-type BiO x F 3−2 x phases (0 < x ⩽ 0.5) is formed. The formation of BiOHal films on the electrode surface proceeds by a stepwise mechanism through intermediate formation of bismuth halide complexes BiHal n 3− n , followed by their hydrolysis. In moderately concentrated solutions of KCl and KBr (0.2 mol/l), the anodic potentiodynamic formation of a BiOHal film is fairly well described by a model assuming gradual filling of the electrode surface with a BiOHal layer and simultaneous growth of its thickness with ionic migration in the solution as the rate-determining stage. Then, as the entire electrode surface is covered with the BiOHal film, the limiting stage changes from ionic migration in the solution bulk to ionic diffusion of Hal − in pores in the BiOHal.

Surface mobility in the dealloying of Ag-Cd alloys in halide solutions

Dealloying of wire samples of Ag-30Cd and Ag-20Cd alloys was studied, at constant potential, in KCl, KBr and KI solutions. Dealloying was found only at those potentials where the respective silver halides were formed, and could be accelerated by straining the wires. It was concluded that surface mobility was the rate controlling step in the dealloying of these alloys. No evidence of stress corrosion cracking could be detected on the strained samples.

Electrochemical adsorption and phase formation of TlBr and TlI on Tl(Hg)

The formation of TlBr and TlI on thallium amalgam electrodes in KBr and KI solutions has been investigated in detail by linear sweep voltammetry, potential step and galvanostatic methods. The results show that growth of the three dimensional bulk phase is preceded by the formation of two-dimensional layers. The behaviour of both systems in the two-dimensional regime clearly does not correspond to the nucleation and growth of a two dimensional layer by the incorporation of new material at the periphery of expanding circular centres; instead, the first monolayers of TlBr and TlI are formed by ohmic controlled adsorption after an initial activated step which appears to involve nucleative behaviour. The adsorption isotherm in both systems shows a step that is probably associated with a transformation which leads to an increase in packing density of the adsorbate. The second monolayers, which appear as metastable phases under dynamic conditions, are formed by a nucleation and growth mechanism.

Iodine dispersion and effects on groundwater chemistry following a release to a peat bog, Manitoba, Canada

The migration and behaviour of I was investigated in a sphagnum bog on the Precambrian Shield in eastern Manitoba, Canada. A 6 M solution of KI was released at the base of the bog to stimulate a pulse discharge of contaminated groundwater from a fracture in the granitic rock. A network of piezometer tubes was used to monitor the dispersion of the I and the groundwater chemistry over 1 year. Cores of peat were also taken for analysis to supplement the groundwater data and to investigate the sorption of I. The introduced I dispersed 2 m horizontally and 1 m vertically within a month. After this, the system stabilized and further migration was insignificant. The pattern of I dispersion indicated that the bog hydrology was very complex with flow directions changing substantially with depth. The groundwater concentrations of the major cations rose in response to the mass action effect of K displacing them from reaction sites in the peat. Humic materials in the groundwater decreased in size after the KI release and returned to their pre-release conformation one month later. The geometric mean soil distribution coefficient value, K d , for I in the bog was 1.36l/kg, but it was strongly related to pore water concentration. Thus, a single K d value was insufficient for describing the system. Clearly, good groundwater chemistry, sorption and hydrological data are necessary for meaningful modelling of contaminant transport in bogs.

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.

Uphill transport of iodide ions through a membrane of poly(vinyl acetate)-iodine-iodide complex

A transient uphill transport of iodide ions was found when the membrane of a poly(vinyl acetate) complex with iodine-iodide separated two KI solutions of different concentrations. Effects of temperature, salt concentration, concentration gradient of the solutions, rinsing methods, and swelling behavior on the permeation behavior were investigated. A transient asymmetric distribution of the fixed tri-iodide ion was presumed to appear when the membrane separated two solutions of different concentrations. The asymmetric distribution of the fixed charge was also presumed to provide a driving force for uphill transport through an electrochemical gradient in the membrane.

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.

Translational and rotational molecular motion in solutions of alkali-metal halides in dimethyl sulphoxide

The relative proton relaxation rates 1/T1 and the translational diffusion coefficients of dimethyl sulphoxide (DMSO) in solutions of NaBr, KBr, Nal, KI, RBl and CsI have been measured at 25 °C. The n.m.r. B′ coefficients and the self-diffusion BD coefficients have been determined for all the salts. For a given salt the B′ and BD values are equal within the experimental error limits. A comparison of these data with literature values for the viscosity B coefficients of the same systems revealed that in DMSO (and in other organic liquids) the viscosity B coefficients always have higher values than the corresponding B′ and BD coefficients. Thus, the viscosity is more strongly influenced by the presence of the ions than the reorientational and translational molecular motion of the solvent. The n.m.r. B′ coefficients have been split into intra- and inter-molecular contributions (B′intra and B′inter) and into single-ion values. Thus the ratio τ±c/τ0c of the reorientational correlation time in the first solvation sphere of the ions to the reorientationl correlation time in the bulk could be determind. These values reflect the relatively strong ion–solvent interaction; however, the Na+–DMSO interaction turns out to be weaker than expected. The equality of B′intra and BD found for all systems leads to the conclusion that in the aprotic solvent DMSO strong coupling exists between translational and rotational molecular motion.

Standard potential and chemical solvation energy of an electron in ethylenediamine

Potential sweep and cyclic voltammetry was carried out in ethylenediamine solutions of LiCl, LiI, NaI, KI and CsI. In all of the solutions electrolytic generation of solvated electrons was confirmed by the observation of a blue cloud formation around a tungsten electrode at potentials where a sharp increase in cathodic current occurred. From the Tafel plots of the cathodic currents, the electrode reaction schemes for the respective salt solutions were described in terms of the solvated electron species: free solvated electron e − s , ion-pair M + · e − s and alkali anion M −. Taking account of the solute equilibria, the standard potential of e − s was found to be −2.57 ± 0.01 V referred to the E 1 2 value of bis(biphenyl)chromium(I). From an extra-thermodynamic assumption with this potential value, the chemical solvation energy of e − s in ethylenediamine was determined as −1.31 eV.