Solvent Extraction and Spectrophotometric Determination of Uranium(VI) with 2,8,14,20-Tetramethyl-11,23-dinitrocavitand-5,17-dihydroxamic Acid

Uranium is extracted, separated, and recovered using 2,8,14,20-tetramethyl-11,23-dinitrocavitand-5,17-dihydroxamic acid (NMCDH) in the presence of diverse ions. Uranium forms a yellow complex with NMCDH in n-octanol with the maximum absorbance at 450 nm and molar absorptivity of 5.0 × 104 L mol–1 cm–1. It follows Beer’s law in the concentration range of 0.48–5.76 µg mL–1. The extracted complex is directly analyzed using ICP-MS with considerably higher sensitivity (detection limit 0.5 ng mL–1). The extraction constants of the uranium(VI)–NMCDH complex are determined. This method enables recovery of 99.95% pure uranium from monazite sand and phosphate rock; it is also effective for preconcentrating and detecting uranium in environmental samples.