Polarographic waves of tri-n-butyl phosphate and polarographic determination of uranium in the presence of tri-n-butyl phosphate

The results of a study on the polarographic behaviour of TBP and its influence on the determination of uranyl ions is presented. The half-wave potential of the adsorption wave of TBP depends on the concentration of TBP, type of supporting elec trolyte and its concentration. In the presence of TBP the polarographic wave of U(VI) ion is changed. Below 7·10^?5 M TBP the polarographic wave of U(VI) is not affected, between 7·10^?5 and 2·10^?4 M TBP the shape, height and half-wave potential of U(VI) waves are changed and above 2·10^?4 M, up to saturated solution of TBP, the waves of U(VI) do, not change further. The bes supporting electrolytes for the determination of U(VI) are KNO₃ or NaClO₄ in concentrations of 0.1 to 0.5 M, pH 1–2 and TBP concentrations from 3·10^?4 to 1.2·10^?3 M.     

Selective extraction of calcium on tri-n-butyl phosphate plasticized selective extraction of calcium on tri-n-butyl phosphate plasticized polyurethane foam for its spectrophotometric determination in glass and ceramics.

The present paper describes the application of a solid phase extraction system in order to separate traces of calcium from glass and ceramics for its spectrophotometric determination. The method is based on the extraction of calcium from sodium hydroxide solution by tri-n-butyl phosphate (TBP) loaded polyurethane foam (PUF), followed by its elution in hydrochloric acid. The spectrophotometric measurement of the absorbance of calcium complex with calconcarboxylic acid (2-hydroxy-1-(2-hydroxy-4-sulfo-1-naphthylazo)-3-naphthoic acid) takes place at pH 12. The following parameters were studied: effects of sodium hydroxide concentration and temperature on the extraction of calcium, time of equilibration for quantitative calcium extraction, effect of TBP concentration, effect of hydrochloric acid concentration for quantitative elution of calcium from PUF, effect of pH and concentration of calconcarboxylic acid for quantitative formation of the complex with calcium, effect of acetone on the stability of calcium-calconcarboxylic acid complex and influence of diverse ions on calcium sorption by TBP-loaded PUF. The results show that calcium traces can be separated onto TBP-loaded PUF from 0.25 mol L(-1) NaOH at 30 +/- 5 degrees C within 30 min. PUF was loaded with TBP in CCl4 (40% v/v). Elution of calcium was done in 1.0 mol l(-1) HCl. The calcium formed a complex with calconcarboxylic acid at pH 12 and absorbance was measured at 560 nm in acetone-water medium. Molar absorptivity was found to be 1.082 x 10(4) l mol(-1) cm(-1). The method obeys Beer's law from 0.10 to 5.0 microg ml(-1) Ca. The validity of the method was established by its successful application in NIST standard reference materials. The method proposed was applied to determine calcium in glass and ceramic materials. The results of the proposed method are comparable with the results of ICP-AES analysis and they are found to be in good agreement.     

PVT properties of PUREX/UREX solvent tri-n-butyl phosphate

Tri-n-butyl phosphate (TBP) is the workhorse of solvent extraction operations in nuclear fuel cycle as well as an important industrial chemical. Its PVT properties are not available in literature. In this study, PVT properties of TBP, estimated using group contribution method, are reported. Wagner constants were also reported in the range of 273.15?K to critical temperature.     

Separation of metal halide pairs using Amberlite LA-2 and tri-n-butyl phosphate

Separation factors of silver-cadmium and silver-zinc pairs were determined for Amberlite LA-2 and tri-n-butyl phosphate (TBP) from pure hydrochloric, hydrobromic, sulphuric and orthophosphoric acids as well as from their binary mixtures. The separation of cadmium and zinc from macroamounts of silver can be best achieved from ca. 2M H₂SO₄. There are many other media suitable for the separation of trace silver from cadmium and zinc matrices.     

Crystal structure and thermal behavior of a chromium-piperazinium phosphate

(C₄N₂H₁₂)CrO(H_1.5PO₄)₂·H₂O has been synthesized hydrothermally using piperazine as organic template. Its crystal structure was solved ab initio using synchrotron powder X-ray diffraction data [monoclinic, a = 16.9649(4) Å, b = 9.8609(2) Å, c = 7.14375(14) Å, and β = 94.896(3)°, space group P2₁/a, Z = 4]. 1D structure is composed by isolated infinite anionic chains [CrO(H_1.5PO₄)₂]_n (vertex-sharing {CrO₆} octahedra joined by phosphate moieties). Their 2D plate-like morphology is propitiated by a very strong inter-chain interaction (P–O···H···O–P symmetric hydrogen bonds). KAS isoconversional method was applied to determine the activation energy for both thermal and thermo-oxidative decomposition of (C₄N₂H₁₂)CrO(H_1.5PO₄)₂·H₂O.     

Synergistic extraction of uranium(VI) with tri-n-butyl phosphate and i-butyldodecylsulfoxide

Summary The synergistic extraction of uranium(VI) from aqueous nitric acid solution with a mixture of tri-n-butyl phosphate (TBP) and i-butyldodecylsulfoxide (BDSO) in toluene was investigated. The effects of the concentrations of extractant, nitric acid, sodium nitrate and sodium oxalate on the distribution ratios of uranium(VI) have been studied. The values of enthalpy change for the extraction reactions with BDSO, TBP and a mixture of TBP and BDSO in toluene were -23.2±0.8 kJ/mol, -29.2±1.4 kJ/mol and -30.6±0.6 kJ/mol, respectively. It has been found that the maximum synergistic extraction effect occurs when the molar ratio of TBP to BDSO is close to 1. The composition of the complex of the synergistic extraction is UO₂(NO₃)₂ ^. BDSO ^. TBP.     

Quantitative extraction of chromium as blue perchromic acid with tri-n-butyl phosphate

Summary Chromium is readily and quantitatively extracted as blue perchromic acid by tri-n-butyl phosphate (25% solution in benzene). The colour remains stable for long periods. The chromium can be estimated either by back extraction into aqueous phase followed by volumetric determination or by direct measurement of intensity of the blue colour in organic phase. The method is free from interference by several elements.

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Zusammenfassung Chrom kann mit einer 25%igen Lösung von Tri-n-butylphosphat in Benzol quantitativ als blaue Perchromsäure extrahiert werden. Die Farbe bleibt lange Zeit beständig. Die Bestimmung des Chroms kann entweder volumetrisch nach Rückextraktion in wäßriger Phase oder durch direkte Messung der Farbintensität in der organischen Phase erfolgen. Mehrere Elemente, die auf ihren störenden Einfluß untersucht wurden, behindern die Bestimmung nicht.

     

Selective extraction of cerium(IV) on tri-n-butyl phosphate and thenoyltrifluoroacetone loaded polyurethane foam

A method for the selective extraction of cerium (IV) on tri-n-butyl phosphate and thenoyltrifluoroacetone loaded foams is described. Parameters affecting the extraction of the metal ion, such as pH, reagent concentration and equilibration time have been investigated. Effects of ten diverse cations have also been studied. The method can be applied to preconcentrate and determine cerium in glasses.This work was performed at the University of Veszprém, Department of Radiochemistry, by A.R. acting as guest research fellow.     

Extraction behaviour of uranium,zirconium and ruthenium with gamma-irradiated sulfoxides and tri-n-butyl phosphate

The extraction, scrubbing and stripping behaviour of uranium, zirconium and ruthenium with di-n-hexyl and di-n-octyl sulfoxides in Solvesso-100 and tri-n-butyl phosphate (TBP) in shell Sol-T irradiated by various gamma doses (0–169 Mrads) have been investigated. 2M HNO₃ was used for extraction and scrubbing and 0.01M HNO₃ for stripping purposes. Results indicate that the extraction of uranium with TBP increases and that with sulfoxide decreases with dose. This is reflected in their corresponding scrubbing percentages too. The stripping percentage of uranium with TBP decreases with dose while the reverse is the case with sulfoxide. The extraction of zirconium with TBP increases sharply with dose as compared to sulfoxides. The extraction scrubbing and stripping of ruthenium remain almost unaffected by dose both in the case of TBP and sulfoxides. These results lead to much higher overall decontamination factors for uranium with respect to zirconium as well as ruthenium with irradiated sulfoxides as compared to those with irradiated TBP.     

Reversed-phase extraction chromatography of iron(III) with tri-n-butyl phosphate on silica gel

Iron(III) is separated by reversed-phase extraction chromatography with TBP as the stationary phase on a column of silica gel, with 2-6M hydrochloric acid as the mobile phase. From knowledge of the distribution coefficients, several separations have been devised, such as separation of Fe(III) from alkali and alkaline earth metals, chromium, manganese, cobalt, nickel, copper, vanadium zirconium, thorium, uranium, yttrium and titanium.     

Polarographic determination of uranium(VI) in aqueous tri-n-butyl phosphate solutions

The effect of TBP as well as the organic diluents on the polarographic wave of U(VI) reduction has been investigated in sulphuric and perchloric acids. It was found that the presence of TBP traces in the solution to be analyzed induced another wave which was more prominent in sulphuric acid solutions. This can be eliminated by boiling the solutions for about 5 min before their analysis for uranium. The effect of supporting electrolyte on the polarographic reduction of U(VI) was also studied and the use of 6N HClO₄ was recommended.     

Absorption kinetics of uranium tri-n-butyl phosphate in the rat: Implications for occupational exposure

The absorption kinetics for uranium into blood after deposition as tri-n-butylphosphate (UTBP) in the rat lung were combined with human data on particle deposition and clearance from the ICRP Publication 66 respiratory tract model and information from the most recent ICRP biokinetic model for uranium to predict the consequences for exposure of workers. These predictions suggest that, (1) the biokinetics of UTBP are similar to those for a Type F compound as defined by ICRP, (2) the dose coefficient is essentially independent of the aerosol size and isotopic composition, (3) the mass of uranium equivalent to the ALI can vary by 13 fold depending upon the isotopic composition, (4) intakes of uranium as UTBP other than chronic intakes as highly enriched forms should be restricted on the basis of the chemical toxicity of uranium, (5) the assessment of intake by urine bioassay measurements should be interpreted with caution unless the exposure conditions are well defined and (6) severe kidney damage is unlikely at intakes corresponding to the ALI or daily limit.     

Properties of the extraction system constituted by phosphoric acid produced from Khibiny apatite and tri-n-butyl phosphate

Data on the equilibrium distribution of phosphoric acid among the aqueous and organic phases in extraction of phosphoric acid with tri-n-butyl phosphate are presented for the system constituted by phosphoric acid produced from the Khibiny concentrate and by the extracting agent from the industrial system for purification of extraction phosphoric acid at 25–50°C.     

Effect of diluent additives on the rate of water purification to remove microdrops of tri-n-butyl phosphate by hydrodynamic heteroadagulation

Effect of diluents on the coarsening of microdrops of tri-n-butyl phosphate by hydrodynamic heteroadagulation on a carbon fabric in water was studied.