Supercritical Fluid Dissolution and Extraction of Trivalent Metal Cations from Different Matrices

Abstract

Studies on the recovery of trivalent metal ions such as Nd³⁺Eu³⁺ (taken as homologs of Am(III)) from solid oxide (Nd₂O₃), Thorium concentrate (obtained from Monazite ore processing), tissue paper/surgical gloves (rubber), and plant samples have been carried out by supercritical fluid extraction (SFE) using supercritical CO₂ and ethanol/nitric acid. N,N,N’,N’-tetraoctyl diglycolamide (TODGA) was used as the extractant in these studies. The results showed that the recovery of Nd increased with TODGA concentration from 50% (no TODGA) to 70% (10% TODGA) at 3 M HNO₃ in ethanol. However, the extraction of Nd at 1 M HNO₃ was invariant with 1-3% (v/v) TODGA concentration (73 ± 4%). Interestingly, REEs recovery from Th concentrate was ˜ 60% even without TODGA using ethanol/3 M HNO₃ mixture. On the other hand, quantitative recovery of ^152,154Eu from tissue paper and surgical gloves sample could be achieved using 3 M HNO₃/ethanol mixture. This suggested that it would be possible to decontaminate the contaminated laboratory waste papers using SFE technique.

Keywords:

• SFE
• lanthanides
• actinides
• TODGA
• plant
• Th concentrate

ACKNOWLEDGEMENTS

The authors thank Dr. A. Goswami, Head, Radiochemistry Division, Bhabha Atomic Research Centre, Mumbai, for his keen interest in this work. They are also thankful to Dr. N. L. Misra, Fuel Chemistry Division, Bhabha Atomic Research Centre, Mumbai, for the analysis of soil by XRD and EDXRF techniques.