Kenji Motojima

Spectrophotometric determination of ruthenium with 8-quinolinol

A spectrophotometric method is described for the determination of 2-80 mug of ruthenium. The method involves oxidation of ruthenium to ruthenate, addition of 8-quinolinol, adjustment of the pH to 4-6.5, digestion of the complex formed at 85 degrees for 30 min, extraction with chloroform, and measurement of absorbance at 430 nm. Almost all other metals and excess of reagent are removed by washing the extract. About 98 % of (106)Ru tracer was recovered.

Determination of traces of ruthenium by addition of cerium(IV) and atomic absorption spectrometry

Abstract The sensitivity of the determination of ruthenium by flame atomic absorption spectrometry is increased 60 times by adding 1 × 10 −2 M cerium(IV). Calibration is linear over the range of 0.05–5 μg ml −1 ruthenium. A method applicable to nitrosylruthenium complexes is described. The increased sensitivity results from formation of ruthenium tetroxide.

Removal of radiocobalt in waste water by activated charcoal using oxine as a chelating agent

Abstract The characteristics of the adsorption of Co ion in water on activated charcoal impregnated with oxine have been studied. Impregnation of oxine largely improved the adsorption capacity of activated charcoal (AC), although the apparent initial and final adsorption rates are not influenced. Another important advantage of AC impregnated with oxine [AC(HOx)] over plain AC is that Co ion collected on AC(HOx) is not easily eluted by flowing water. Furthermore the collection of Co on AC (Hox) is not affected by the presence of Fe(III), which exists in a macroscopic amount in waste water. At the initial adsorption stage, the apparent adsorption rate of Co ion on AC (HOx) is roughly proportional to 0.91 power of the concentration of Co ion.

DETERMINATION OF PLUTONIUM BY TWO-STEP FLOW-COULOMETRY AT THE COLUMN ELECTRODE.

A two-step flow-coulometry method has been developed for rapid determination of elements (plutonium, iron, etc) which exist in various oxidation states in solution, and applied to the determination of plutonium in 0.5M sulphuric acid medium. The first-step column electrode potential is fixed at between +0.10 and +0.35 V vs. Ag-AgCl, and all plutonium ions are reduced to Pu(III). The second-step column electrode potential is fixed at +0.75 V vs. Ag-AgCl, and Pu(III) which flows from the first column electrode is oxidized to Pu(IV). The quantity of plutonium is determined from the number of coulombs used in the oxidation. It is possible to eliminate interference by diverse ions by electroanalysis at the first column electrode. About a 10-mul sample is necessary and the electrolysis for determination is finished in 1 min.

Trapping and recovery of radioiodine compounds by copper metal

Abstract The performance of Cu metal as an adsorbent for volatile radioiodine compounds, I2∗, HI∗ and CH3I∗ has been examined. Both I2∗ and HI∗ are effectively trapped. However, for the complete trapping of organic iodide, a process converting it into inorganic form must precede the trapping process. The iodine, trapped on the reduced Cu, is easily released as HI∗ by stream of H2 gas above 400°C. Compared to other conventional procedures, this trapping procedure has the advantage that Cu is regenerated during the recovery process to be used again.

Preliminary study on sublimation separation of 99Mo from neutron- irradiated UO2

Abstract For the purpose of developing the method of separating 99 Mo from irradiated UO 2 by sublimation, fundamental studies have been made on the temperature dependencies of sublimation of 99 Mo, 132 Te and 103 Ru and also on the behavior of 131 I, which is an important nuclidee because of the hazardness. The irradiated UO 2 is converted to U 3 O 8 by heating at about 500°C in an oxygen atmosphere of 1 2 kg/cm 2 and then the nuclides are separated from U 3 O 8 by heating at 1200°C under vacuum. The sublimated 131 I is identified to be elemental iodine and iodide, and it is trapped on copper metal grains. The trapped iodine is recovered as HI by heating in H 2 gas at 550°C; it is radiochemically pure.

STUDY OF OXIDATION STATE OF PLUTONIUM IN SOLUTION BY FLOW-COULOMETRIC METHOD.

Reduction rates of Pu(IV) and oxidation rates of Pu(III) have been studied in sulphuric acid and nitric acid media, as functions of acid concentration, plutonium concentration and kind of acid. A flow-coulometric method was used in this work. This procedure has many merits, namely, the sample size required is very small, special reagents are not used, fewer limitations are imposed by the type and concentration of acid, and the method is rapid.

Determination of radioactive cobalt in reactor coolant water by solvent extraction

A rapid extraction separation method is described for the radiochenaical determination of cobalt-58 and cobalt-60 in reactor coolant water. After adjustment of the pH of the sample water to 5.0-5.5, cobalt diethyldithiocarbamate is extracted with benzene. Other nuclides, e.g., manganese-54 and -56, copper-64 and iron-59, which are usually present in reactor coolant water, are also extracted together with cobalt. However, they can be readily removed by washing the extract with mercury(II) chloride solution. The cobalt-58 and -60 activities are measured by gamma counting of an aliquot of the washed extract. Trace amounts of radioactive cobalt in 500 ml of sample water can be quantitatively extracted without the use of carrier. The separation could be finished in 15 min and an average recovery of 99.5 % was obtained, with a relative standard deviation of 1.4% (25 experiments).

Determination of Microamount of Aluminum, Chromium, Copper, Iron, Manganese, Molybdenum and Nickel in Pure Water by Extraction Photometry

Aluminum, iron (III), copper, and molybdenum 8-quinolinol complexes, chromium (III) and manganese 8-hydroxyquinaldine complexes and nickel dimethylglyoxime complex can be quantitatively extracted into chloroform from large volumes of aqueous phases adjusted to an approriate pH for each metal. These metals can be determined by measuring the absorbance of the organic phases containing their complexes at an appropriate wavelength for each metal. By the proposed method, quantities exceeding 3 p.p.b. of aluminum, chromium, and manganese, and 5 p.p.b. of copper, iron, molybdenum and nickel can be determined when a 500 ml sample of water is available.

Removal of Radiocobalt Ion in Waste Water by Oxine-Impregnated Activated Charcoal. Part II: Column Experiments

Cobalt ion in a flowing solution was adsorbed onto the oxine-impregnated activated charcoal in a column. The initial rate of adsorption, K A/sub m/, is influenced by either the flowrate or the ion concentration of a feed solution. The rate increases with a decrease in the concentration of the ion. However, with a solution of < 0.06 ..mu.. g ml/sup -1/ of the ion, the adsorption rate tends to be constant at 0.90 +- 0.06 min/sup -1/. A relation between feed application time and column depth (bed depth/service time) has been determined that qualitatively agrees with that obtained from a theoretical calculation. Feed application time for different concentrations and flowrates of feed solutions can be predicted by the bed depth/service time relation with a limited accuracy.