Determination of small amounts of uranium by redox potentiometric titration

Yakshin, V. V.; Krokhin, M. N.

doi:10.1134/s1066362211030179

Cited by 8 publications

(2 citation statements)

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“…The most accurate are gravimetric and titrimetric methods widely used in quantitative determination of U [3][4][5][6]. The use of redox potentiometric titration methods with automatic titrators allows the determinable amount of U to be decreased to 4-5 mg with the sufficient measurement accuracy preserved [6,7].…”

Section: Resultsmentioning

confidence: 99%

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Improvement of the potentiometric method for uranium determination in solutions

Yakshin¹,

Krokhin²

2012

Radiochemistry

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Redox potentiometric titration of small amounts of U in mixed phosphoric-sulfuric acid systems with an automatic titrator was studied. The U determination accuracy is strongly affected by the aqueous phase composition and kind of titrant. In determination of 0.1-0.2 mg of U in mixed phosphoric-sulfuric acid solutions containing 6 M H 3 PO 4 and 1.25 M H 2 SO 4 , the titrant efficiency decreases in the order NH 4 VO 3 > KMnO 4 > Ce(SO 4 ) 2 > K 2 Cr 2 O 7 . In 2 M H 2 SO 4 , the use of KMnO 4 as titrant allows determination of 0.02-0.1 mg of U with the uncertainty within 10%.Accurate quantitative determination of U in multicomponent solutions from reprocessing of uraniumcontaining products remains a topical problem, despite availability of such analytical monitoring methods as X-ray fluorescence analysis (XFA) and inductively coupled plasma atomic emission spectroscopy (ICP-AES) [1]. In some cases, the results of U determination in process solutions by XFA and ICP-AES show good agreement with the results obtained by common volumetric redox titration [2]. The need for developing new methods for U determination is caused by a number of significant drawbacks of the classical titrimetric method, such as the use of a set of titrated working solutions and difficult determination of the equivalence point because of the interfering effect of impurities.These drawbacks are largely eliminated in going to redox titration with potentiometric detection of the equivalence point [3,4]. The use of automatic titrators with accurate fixation of the equivalence point by the first derivative additionally enhances the potentialities of the method [5]. Automatic titrators (in particular, ATP-02) allow analysis of strongly colored solutions, which eliminates visual error in titration, and the use of different titrants. Another advantage of potentiometric methods is the possibility of determining U in multicomponent samples without using references.In this connection, it is appropriate to continue studies on further improvement of the automatic potentiometric titration method with the aim to enhance its accuracy, reduce the reagent consumption, and eliminate the effect of interfering impurities. EXPERIMENTAL Equipment.For the titration, we used an ATP-02 automatic titrator with the software developed by Akvilon (Titrate-5.0 program). The main unit of the titrator is a computer-controlled automatic piston buret. The device also includes a voltage measurement channel and an analog-to-digital converter transforming an electrode system signal into a standard digital code delivered to a microprocessor.In the volume measurement channel, pulses are processed and information on the titrant volume fed to the solution is formed. We chose a discrete titration mode with a gradual decrease in the pulse length and mean solution feeding rate, with a simultaneous increase in the pause between the pulses. The maximal titrant feeding rate was 1 ml min -1 , with a single dose of 0.1 ml. The equivalence point was determined from the maximum of the potential...

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Section: Resultsmentioning

confidence: 99%

“…The use of automatic titrators with accurate fixation of the equivalence point by the first derivative additionally enhances the potentialities of the method [5]. Automatic titrators (in particular, ATP-02) allow analysis of strongly colored solutions, which eliminates visual error in titration, and the use of different titrants.…”

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confidence: 99%