Co-Extraction of U(VI) and HNO₃ Using TBP and its Higher Homologues TiAP and TEHP: Comparison of Equilibria, Kinetics, and Rate of Extraction

Abstract

In this work, bulk-liquid membrane (BLM) system is used to compare tri-n-butyl phosphate (TBP), tri-isoamyl phosphate (TiAP), and tris(2-ethylhexyl) phosphate (TEHP) for their relative ability to co-extract U(VI) and nitric acid from aqueous nitric acid feed-phase into water strip-phase, through hydrocarbon membrane-phase. The kinetics of extraction is modelled and the model is validated through experiments. The quantity which determines the efficiency of liquid emulsion membrane (LEM) process is the relative rate of extraction of U(VI) to nitric acid. This is in the order TiAP>TEHP>TBP, indicating that TiAP is most suitable for extraction of U(VI) from nitric acid using LEM.

Keywords:

• co-extraction
• U(VI)
• nitric acid
• TBP
• TiAP
• TEHP
• bulk liquid membranes
• liquid emulsion membranes

ACKNOWLEDGEMENTS

The author, Diptendu Das, wishes to thank Quality Control Division of Uranium Extraction Division (QCS-UED), Bhabha Atomic Research Centre, India for allowing him to carry out the experimental work.