Spectrophotometric study of uranium(VI) chelate formation with beta-diketones and tributyl phosphate in aqueous, nona(oxyethylene) dodecyl ether solution.
The distribution ratio of uranium(VI) with 2-thenoyltrifluoroacetone, 2-furoyltrifluoroacetone and benzoyltrifluoroacetone in the presence and absence of tributyl phosphate between micellar and bulk phases in nona(oxyethylene) dodecyl ether solution was measured spectrophotometrically as a function of hydrogen-ion concentration. The thermodynamic constants for these reactions were evaluated from the variation of the equilibrium constants as a function of temperature. The entropy change contributes to the synergistic reaction.
Radiochemical Assessment of Uranium in Locally Used Marbles
A sensitive method is used for the extraction and determination of soluble uranium in locally used marble has been developed. Isobutyl Methyl Ketone (IBMK) was used as extractant and 0.02 % (w/v) Arsenazo (III) as a chromogenic reagent. The present study assesses the gross radioactivity and extractable uranium in marble samples. A Multichannel Analyzer (MCA) coupled with NaI (Tl) crystal detector was used for the measurement of gross radioactivity whereas spectrophotometer was used to estimate the uranium contained in sample with the help of Arsenazo (III). The extraction involved the adjustment of pH at 0.9. The efficient extraction was achieved by the addition of at least 10 g of Al (NO3)3. This method involved the reduction of UO2 (+2) to U (IV) by using granulated Zinc in concentrated hydrochloric acid. The physical measurements showed the presence of gross radioactivity in the range 266.19 Bq/kg to 644.268 Bq/Kg while the chemical analysis showed the uranium concentration in the range of 0.02ppm to 0.06 ppm.
The role of dissolved oxygen in supercritical water in the oxidation of ferritic–martensitic steel
Abstract To assess the role of dissolved oxygen in supercritical water on the growth processes of oxide scales, a marker experiment of ferritic–martensitic steel was performed by exposing to supercritical water (H 2 16 O) containing marked 18 O 2 at 600 °C under 25 MPa. The oxide scale was analysed by using Secondary Ion Mass Spectrometry (SIMS). The oxygen isotope profile shows that dissolved oxygen and supercritical water react with metals simultaneously. Dissolved oxygen changes the oxidation/reduction potential of supercritical water leading to an increase in the oxidation rate. The oxidation rate increases with increase in dissolved oxygen content in supercritical water. The mechanism of the effect of dissolved oxygen on oxidation is discussed.