RadChem 2010

Separation, preconcentration of lanthanum from monazite and its determination by ¹³⁸La using non-destructive γ ray

20 Apr 2010, 11:45

1h 30m

Gallery (Casino Conference Centre)

Board: NAM.P15

Poster Nuclear Analytical Methods Poster Session - Nuclear Analytical Methods

Speaker

Prof. Ashraf El-Sayed (Atomic Energy Authority, Hot lab center, Analytical Chemistry Departments,)

Description

Abstract A method developed for separation preconcentration and determination of Lanthanum elements which consists of mainly two isotopes, the stable La-139 and the radioactive La-138 with its half life 1.05 E-11 years. The stable isotope La-139 is being the most abundant ratio 99.911±0.001% while La-138 has only 0.089±0.001% abundance ratio. Lanthanum-138 also has two main gamma ray energy lines one at 788.4 and the other at 1435.8 keV which were using for the determination of La-139 by Hyper Pure Germanium detector, HPGe. Based on this method, the percent of La-139 has been calculated with high precision in a synthetic samples. The results were compared with inductively coupled plasma- mass spectroscopy, ICP-MS, technique. The detection limit was calculated as MDA (minimum detection activity) and it has been found to be equal 1.46 Bq/kg for La-138 at 788.4 Kev and 1.52 Bq/kg at 1435.8 Kev gamma ray energy lines with mean value 1.49 Bq/Kg. Application of that method was successfully applied for the determination of lanthanum in natural sample; Monazite. The developed method was based on new chemical steps; precipitation and solvent extraction for such crude specimen monazite sample, for the lanthanide determination was established. Where, the precipitation method is used for removal of Th (IV) and U (VI) and the solvent extraction is used for removal of Ac from REEs. Molar Solution HDEHP in benzene was applied to extract REEs and Actinium, Ac, from 0.1M HNO3 while the 0.2M HNO3 is used to stripe Ac leaves REEs in the organic phase. Therefore, lanthanum in the residual REE was accurately determined.