Iodine Volatility Research Articles

Volatilization of methyl iodide from the soil-plant system

Iodine volatilization from the soil-plant system has been studied by radiotracer experiments and gas chromatography. Iodine emission was highly stimulated by the presence of plants. A marked emission of gaseous iodine from rice plants grown on flooded soil was observed, whereas oat plants showed considerably lower emission. Seasonal patterns in the iodine emission were observed for both plants. The emission rate increased with time from planting and the maximum value was observed in the late tillering stages (shortly before heading) of the plants. The chemical species of volatilized iodine was identified as methyl iodide (CH 3I) from gas chromatography. It was presumed that iodine in the flooded soil was methylated by the action of roots or microorganisms. The methyl iodide produced was mainly emitted, not from the soil surface, but from the plant shoot into the atmosphere.

The impact of organic compounds on pH and iodine volatility in nuclear reactor containment structures

The effect of organic compounds on the production of volatile species of iodine was examined. The first step has been to identify candidates for detailed study through a series of scoping experiments, in which the chemical environment existing in CANDU reactor containment is simulated. These experiments have involved the irradiation of 10−5M CsI solutions labelled with131I containing a dilute concentration of a particular organic compound (8.5·10−3 to 1.4·10−1M). A total of 20 compounds and polymers have been tested to date. Results have shown that many of these compounds do enhance iodine volatility, and that the degree of volatility is related to system pH. Using the iodine partition coefficient (H=iodine concentration in the liquid phase/iodine concentration in the gas phase) as a basis, values as low as 300 have been observed for chloroform solutions. Conversely some compounds, such as phenol, have produced low volatility, with values of 1·105. As a reference, a partition coefficient of 104 has often been used in safety analysis.

On-line preconcentration and volatilization of iodine for inductively coupled plasma atomic emission spectrometry

On-line preconcentration and volatilization of iodine for inductively coupled plasma atomic emission spectrometry

Systematic design of chemical oscillators. 63. Large amplitude pH oscillation in the oxidation of hydroxylamine by iodate in a continuous-flow stirred tank reactor

Large amplitude pH oscillation occurs in the iodate oxidation of hydroxylamine in a continuous-flow stirred tank reactor (CSTR) in a narrow range of flow rates and input concentrations. In addition to pH, the redox potential, the iodide ion concentration, the rate of gas (N20) formation, and the color of the solution (1,) change periodically. The oscillatory period is extremely long, 2-6 h. The dynamical behavior of the reaction was modeled by a scheme that takes into account the following component processes: the protonation equilibrium of NHzOH, the dissociation of water, the direct redox reaction between IO3and NH30H+, the Dushman reaction between IO; and I-, the autoinhibitory reaction between I2 and NH30H+, the fast dimerization of NOH to N20, the reaction of NOH with NH,OH, and the volatility of iodine. Empirical rate laws of the component reactions were used successfully to calculate the kinetic behavior in a closed system, as well as in the CSTR.

Volatilization of iodine from vegetation

Gaseous emissions of iodine were measured from bean plant foliage. A gamma-emitting iodine tracer, Na 125I, was taken up by the plants from a hydroponic growth medium and released to a cuvette atmosphere. The dynamics of the flux were studied using a flow-through gamma detector. The relationship between leaf radioactive tracer activity and growth-medium activity was linear, as was the relationship between the iodine flux and both leaf and growth-medium activity. Iodine flux and leaf conductance to water responded similarly to changes in light levels, suggesting that the stomata may partially control the flux. The flux was inhibited by aeration of the hydroponic growth medium, and we postulate that methylation causes the iodine flux. Iodine emissions from living vegetation probably contribute <0.1 % to the stable iodine concentration in the atmosphere above terrestrial areas. However, this pathway may be a direct route for radioactive iodine transport from contaminated soils to the atmosphere.

Organic Iodide Formation During Severe Accidents in Light Water Nuclear Reactors

The description of containment iodine behavior in reactor accident sequences involves a combination of iodine volatility effects, deposition/revaporization processes, and mass transport of iodine species. The formation and retention of volatile organic iodides such as methyl iodide, CH3I, are important factors in determining iodine source terms. Tests have shown that the formation of organic iodide was enhanced by radiation and iodine in the chemical form of I2. Methyl iodide, the only organic iodide detected in measurable quantities, formed predominantly in aqueous solution even when the organic material was introduced to the gas phase.

Gamma Radiation Effects on Time-Dependent Iodine Partitioning

A need for characterization of the iodine source term used in safety calculations for hypothesized light water reactor core disruptive accidents has motivated a study in iodine volatility. Previous experimental studies have been directed at evaluating volatility of iodine at a single time shortly (1 to 12 h) after introduction into the aqueous phase. The very important variables of time in solution and gamma radiation dose rate for a range of iodine concentrations (10−8 to 10−5 gI/ml) and pHs(5, 9, and 11) are explored. All experiments were performed at ∼25°C, first in the absence of a significant radiation field and later with a gamma radiation dose rate ranging from 0.003 to 0.06 Mrad/h. Iodine was introduced as either molecular I2 or Nal with 131I(8.04-day half-life) as a tracer.Results of experiments with nonirradiated systems indicated very little volatility with Nal-initiated studies. The I2-initiated systems at pH 5 were the most volatile whereas experiments at pH 9 and 11 showed decreasing iodine volatility with time. From the experiments at pH 9, it is inferred that the partition coefficient of HOI is ∼1000.A pronounced radiation-induced reduction in iodine volatility in pH 5 iodide solutions has been demonstrated as well as a dose rate dependence in the transient phase. As with nonirradiated systems, irradiated alkaline solutions exhibit low volatility.A computer-based model incorporating water radiolysis and iodine radiolytic chemical reactions has been formulated and tested. The model successfully predicts radiation-induced volatility changes in pH 5 iodide systems. The experimentally observed dose rate dependence is also verified. At pH 9, the agreement between experimental results and predicted results is not good.

純水に対する溶存酸素濃度の測定 主として溶解度について

This report describes the experimental procedure and the measurement of oxygen solubility (dissolved oxygen concentration with air) in pure water, which is used for the calibration of dissolved oxygen meters. The solubility in the region of 0-40°C C was measured by means of modified Winkler titrimetric technique in which the iodine volatilization was controlled. Experimental result showed that the solubility c5 (mg/l) at temperature t (°C) was expressed with following polynominal equation and its accuracy was better than ±0.4 %. c5 = 14.536- 0.4049t+ 8.520×10-3t2-1.123×10-4t3 + 6.34×10-7t4.The influences, of the iodine volatilization, the atmospheric pressure, and dissolved oxygen in reagents on the measured value were discussed and the result was compared with the previous works.

Comparison and evaluation of different methods for α-MSH labelling

We have studied the behaviour of 125I-labelled α-MSH under different experimental conditions. Until now, the chloramine T method had been used by most investigators with variable results. We have tested three other labelling techniques based on 125I mild oxidation: (1) an enzymatic method with lactoperoxidase, (2) a sparingly soluble chloramine method (T.D.G.U.), and (3) modified chloramine T procedure, ‘the iodine volatilization method’. Labelled hormone obtained after each kind of iodination was assayed for immunoreactivity. In addition, time course degradation was measured by classical RIA incubation procedures. Charcoal-dextran was used to separate bound and free antigen. We have found chloramine T-iodinated α-MSH to be significantly more damaged than preparations obtained by other methods and to be less stable when stored at −18°C. No differences were found between the differently labelled 125I-labelled α-MSH fresh preparations in binding to surface receptors of human melanoma cell lines in culture.

Iodimetric determination of copper(II) in the presence of polyvinylpyrrolidone

The iodimetric determination of copper(II) in the presence of polyvinylpyrrolidone has been studied. Under these conditions, the determination was apparently carried out in the absence of a copper(I) iodide precipitate and so avoided any errors produced by the adsorption of iodine. The presence of the polymer decreases the volatility of iodine, thus avoiding further possible losses. Because the presence of polyvinylpyrrolidone enhances the colour of iodine solutions auto-indication may be used. The proposed method was applied to the determination of copper in a brass sample.

Volatility of iodine in dilute aqueous solutions

Abstract The equilibrium partition coefficients of iodine species between water and gas phase as a function of iodine concentration have been measured. At very low concentrations the partition coefficients have been determined to be ∼7800 and ∼1650 at 21 and 72°C, respectively. The results of chemical analyses for iodine species in both phases provide convincing evidence of the existence of hypoiodous acid (HIO) in both phases in low concentration experiments. The partition coefficient data are used to estimate the equilibrium constant and some thermodynamic properties of HIO. The results of field measurements of radioiodine separation factors at the gas-water inter-phase in operating boiling water reactors (BWR) are also presented.

Analysis of Ozone in Aqueous Solutions Using A Modified Iodometric Technique with as (III)

Abstract A modified iodometric procedure using an absorbing solution of 2% NBKI with a known amount of As(III) is described for 10 ml aqueous samples. Ozone contents from 0.5 to 65 mg O3/I were determined. High ozone concentrations can also be measured for generator calibration. This method gives results which are not significantly different than a boric acid method but are for a modified standard methods procedure. Volatility of iodine has been completely eliminated. Stabilized samples do not make the time between sampling and final titration critical.

Protein radioiodination in a radioassay laboratory: evaluation of commercial Na125I reagents and related biohazards.

Three commercial Na125I solutions (Amersham, New England Nuclear, and Union Carbide) have been examined with respect to multiple parameters affecting their use in the radioiodination of three representative peptides (insulin, growth hormone, and gastrin): % of radioiodine incorporation in protein; immunoreactivity and non-specific binding properties of the radiolabeled proteins; pH, volatility, and radionuclidic purity of radioiodine solutions; and vial construction with respect to multidose use. All three commercial Na125I produced radioiodinated proteins of good quality for use in radioligand assays. The radioiodines differed with respect to the amount of iodine released during initial vial opening as a consequence of different pH levels: 15 nCi/mCi (pH 12.5) to 1.0 microCi/mCi (pH 7.5). Two of the three products were shipped in vials with poor construction with respect to multidose use. Selection of a radioiodine was therefore reduced to the secondary considerations of iodine volatility and vial construction. The volatilized radioiodine observed during the spill of millicuries quantities of unbuffered pH 7.5 Na125I was 14 microcuries per millicurie within the first 30 minutes. One thickness of rubber gloves reduced potential skin contamination from an accidental spill to insignificant levels: 20-30 picocuries per microcurie. Common good housekeeping procedures: i.e. rubber gloves, laboratory coat and a fume hood were found to be sufficient protection to eliminate most radioiodine volatility and contamination hazards associated with protein radiolabeling procedures.

Determination of dissolved oxygen by the winkler method and the solubility of oxygen in pure water and sea water

AbstractValues for the solubility of oxygen in water obtained by a modification of the Winkler method are shown to be low because of losses of iodine vapour. Iodine vapour is also lost in two of the standard modifications of the Winkler method in common use, the amount lost depending on the technique of the analyst.The volatilisation of iodine can be avoided by the use of the alkaline iodide reagent of Pomeroy &amp; Kirschman; a procedure employing this reagent is described. Interference by pitrites and ferric iron may be eliminated by sodium azide and phosphoric acid respectively.The accuracy of the Winkler method, modified to prevent the loss of iodine vapour, has been confirmed using gaseous oxygen as a standard.Using the procedure recommended, determinations have been made of the solubility of atmospheric oxygen in distilled water between 0·4° and 37°, and in sea water between 2° and 27°. The results for distilled water are in excellent agreement with those of Klots &amp; Benson between 2° and 27°; the new values for sea water agree fairly well with those of Fox.In measurements of the rate of solution of oxygen, the approach to equilibrium using these values was consistent with the law of Adeney &amp; Becker.

光度滴定法による薬品分析法の研究 (第8報)

Good result can be obtained in photometric titration of potassium iodide in hydro-chioric acid solution by the addition of ethanol and titration with potassium periodate at 290mμ, thereby preventing volatilization of iodine produced. In accordance with this result, potassium iodide and iodine solution are accurately measured, titrated in sulfuric acidity with 0.001M potassium periodate (a cc.), the same amount of the two substances are measured accurately, and titrated with 0.001M potassium periodate in hydrochloric acidity (b cc.), by which a cc. would correspond to the amount of I- and b-5/2a cc. to I2. This method is advantageous in that a minute amount of I2 and I- can be determined by the same oxidation agent.

The Melt Refining of Irradiated Uranium: Application to EBR-II Fast Reactor Fuel. XI. Behavior of Iodine in Melt Refining

Melt refining of synthetic EBR-II alloy in stabilized zirconia crucibles at 1400 ts C for 3 hr under one atmosphere of helium pressure resulted in almost complete volatilization of iodine from ingot and skull fractions. Removal of iodine was strongly dependent on refining temperature. Volatilized products were primarily iodides of metals initially present as minor oxide constituents of the crucible; no evidence for evaporation as free iodine was found in the melt refining operation. (auth)

A study of the alkaline ashing method for determination of protein-bound iodine in serum

1. 1. When protein precipitates were incinerated with NaOH or Na 2CO 3 in crucibles or wide-mouthed test tubes, losses of iodine, in some cases exceeding 50% of 131I added to the precipitates, occurred from volatilization. The loss occurred during the decomposition of the organic matter while the temperature was rising from 400 to 600. Continuation of the heating at 600° did not increase the loss, nor did any loss occur when inorganic 131I was heated with alkali to 600 in the absence of organic matter. 2. 2. The loss of iodine during ineineration could be kept within 2 or 3% by using KOH instead of Na 2CO 3 or NaOH as alkali, and by using incineration vessels of a shape that minimized circulation of gases. Such vessels are tlie 15 by 125 mm test tubes used by BARKER 3, or 50 ml test tubes witli necks narrowed to 8 mm bore. 3. 3. A second loss by volatilization of iodine can occur if tlie dry ash is dissolved in excess acid. The loss appears to occur with the stormy evolution of CO 2. It is avoided if the ash is first extracted with water (vilkki 7) and the acid, necessary for subsequent reaction of Ce(IV) and As(III), is added to the solution instead of to the dry ash. 4. 4. Carbon particles left in the ash by incomplete incineration are difficult to remove from acid solution of the ash by centrifugation. They exert a marked accelerating effect on the reduction of Ce(IV) by As(III), and can cause gross plus errors in estimation of iodine from the rate of reduction. Occurrence of carbon in the ash can be prevented bv marlow's 13 device of adding kclo 3 to the alkali incineration mixture, or by opening the muffle oven for short intervals during incineration, after temperature has reached 600°, to permit access of air to the ash. 5. 5. VILLKI'S 7 demonstration, that inorganic iodine can be separated from serum proteins as completely by 12-hour dialysis as by precipitation and washing of the proteins, is confirmed. However, in the writers' experience, precipitation and washing proved to be more rapid and convenient for routine analyses. 6. 6. A procedure is described for determining the presence of iodine contaminating the reagents. It depends on the fact that a slight amount of mercuric ion inhibits the accelerating effect of iodine on tlie reduction of Ce(IV) by As(III). 7. 7. For determining iodine in the ash extract by means of the catalytic effect of I − on the reduction of Ce(IV) by As(III), conditions of reaction time and of cerie, arsenite, and chloride concentrations have been ascertained such that extinction readings for minimal to maximal iodine values cover the extinction range, 0.70 to 0.15, where percentage error of reading is minimal. 8. 8. A procedure for PBI determination is outlined which is believed to minimize the danger of aberrant results.

Oxidized Iodine in Sea Water

TAKEN together, Sugawara and Terada's experiment A and Johannesson's evidence form more cogent reasons for believing iodate to be the oxidized form of iodine in the sea than the reasons we presented for believing hypoiodous acid to be the oxidized form. However, as we indicated, the volatility of iodine from sea water seems to demand that a large part of the iodine should be in the form of hypoiodite. Unless the volatility can be explained quantitatively in terms of an iodate–iodide mixture, the state of iodine in the sea cannot be considered as satisfactorily settled.

41—The Micro-Determination of Chloride by the Diffusion Technique, and the Chloride Content of Raw Cotton

Conway’s micro-diffusion technique for the determination of chloride has been improved by absorbing the chlorine in a solution of sodium arsenite. This eliminates the error in Conway’s procedure due to volatilization of iodine from the absorbing solution. Maximum recovery of chlorine is obtained when the volume of test solution is a minimum and when a relatively large amount of sodium acetate is pre ent. Ln applying the method to cotton, the cotton ia ashed at 650°C in the presence of sodium carbonate. Analysis of twenty-three different cottons gave results, expressed as sodium chloride, ranging from 0.05 per cent to 0.15 per cent with a mean of 0.08 per cent.

Volatilization of Iodine from Dilute Iodine-Potassium Iodide Solutions

Volatilization of Iodine from Dilute Iodine-Potassium Iodide Solutions