Open AccessAN INVESTIGATION OF THE TRANSFER OF URANYL NITRATE ACROSS THE WATER- TRIBUTYL PHOSPHATE INTERFACE BY THE METHOD OF PHOTOGRAPHIC PHOTOMETRY
Author(s) -
C.V. Chester
Publication year - 1961
Language(s) - English
Resource type - Reports
DOI - 10.2172/4052599
Subject(s) - uranyl nitrate , uranyl , chemistry , tributyl phosphate , nitric acid , diffusion , nitrate , analytical chemistry (journal) , uranium , inorganic chemistry , chromatography , extraction (chemistry) , thermodynamics , materials science , ion , physics , organic chemistry , metallurgy
The resistsnce of the water --tributyl phosphate (TBP) interface to diffusion of uranyl nitrate was investigated by a photographic photometric technique. The resistance was below the limit of detectability in the experiments, even with a surface-active agent present in the system. The sensitivity of the experiments established an upper bound for the interfacial resistance to diffusion equivalent to that of a 25- mu film of TBP under steady- state diffusion. The results indicated that the rate-limiting step in solvent extraction of uranyl nitrate from water by TBP is transfer of the diffusing species between the interface and the bulk phase rather than across the interface. In the experiments a steady-state concentration profile was established across an interface by providing a source of uranyl nitrate on one side and a sink on the other in a special cell. Uranyl nitrate diffused along the concentration gradient and hence across the interface. A resistance to diffusion by the interface would be manifest as a departure from equilibrium of the uranyl concentrations immediately adjacent to and on either side of the interface. Accurate values of the interfacial concentrations at steady state were obtained by extrapolating the profile obtained from a few point measurements on either side. The profiles were computed from densitometric measurements of photographic images of the column which were compared with similar images of standard solutions. (auth