Yh. Lin et al., SUPERCRITICAL-FLUID EXTRACTION OF URANIUM AND THORIUM FROM NITRIC-ACID SOLUTIONS WITH ORGANOPHOSPHORUS REAGENTS, Environmental science & technology, 29(10), 1995, pp. 2706
Uranium and thorium in nitric acid solutions can be effectively extrac
ted by supercritical carbon dioxide containing tributyl phosphate or a
phosphine oxide.