Abstract
Retention behavior of U(VI) and Th(IV) as their 2, 6-pyridine dicarboxylic acid (PDCA) complexes on reversed phase and ion exchange (cation, anion and mixed ion exchange) columns was studied and based on the results, a simple ion chromatography method for the determination of trace level thorium in uranium oxide using 0.075mM 2, 6-pyridine dicarboxylic acid (PDCA) and 1M KNO3 in 1.2M HNO3 as eluent (flow rate 1 mL/min)was proposed. The advantage of the developed method is that the separation of uranium matrix is not required prior to the ion chromatographic determination of trace Th. Separation was carried out on a mixed ion exchange stationary phase and a 10?4 M arsenazo (III) solution was used as post column reagent for detecting the separated metal ions. The separation of Th from uranium using PDCA in the present investigation is attributed through cation exchange mechanism. A calibration plot was constructed by following the standard addition method over the concentration range of 0.25 to 10 ppm of Th in the presence of uranium matrix, which resulted in a linear regression coefficient of 0.9978. The precision of the method was better than 5% and the LOD for Th was found to be 0.1ppm (S/N=3). The method has been validated by comparing the results with the results obtained from ICP-MS analysis where the This separated from the uranium matrix. The proposed method is simple, rapid, accurate and cost effective compared to techniques like ICP-MS or ICP-AES and is suitable for the routine kind of analysis.
Highlights
The development of fast breeder reactors in India is inevitable as India has limited resources of uranium and the vast thorium resources require breeder cycle for exploitation [1,2]
Earlier we reported the separation of U and Th as their pyridine dicarboxylic acid (PDCA) complexes using cation exchange column with a mobile phase of 0.08 mM PDCA in 0.24 M KNO3 and
A study that dealt with the chelation ion chromatography (CIC) separation could successfully separate Th(IV) and U(VI) on a neutral polystyrene resin column dynamically modified with PDCA [14]
Summary
The development of fast breeder reactors in India is inevitable as India has limited resources of uranium and the vast thorium resources require breeder cycle for exploitation [1,2]. We have separated uranium and thorium using a short length cation exchange column using a mobile phase consisting of 0.08 mM PDCA in 0.24 M KNO3 and 0.22 M HNO3 (pH ~ 0.6) [23] This method was found suitable for the rapid separation of both U and Th at trace level concentrations; it would not be possible to extend the procedure when one of the metal ions was at higher concentrations. Since the nuclear fuel samples (mg amounts) are often dissolved in mineral acids and subsequently aliquots are made out of this solution for wet analyses, it is desirable to use PDCA as complexing agent, which would enable the direct injection of the samples into the system The aim of this investigation was to develop a rapid and reliable method for the separation and determination of trace level thorium in uranium oxide using a mixed ion exchanger column and PDCA as a complexing agent
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