Actinides solution

Ferrite is introduced into the aqueous media by two techniques. With the in situ method, ferrite is formed within the actinide-containing solution by addition of Fe(II), Fe(III), and sodium hydroxide. With the preformed ferrite method, ferrite solids are prepared separately and added to the actinide solution. 

The elucidation of actinide chemistry in solution is important for understanding actinide separation and for predicting actinide transport in the environment, particularly with respect to the safety of nuclear waste disposal.72,73 The uranyl CO + ion, for example, has received considerable interest because of its importance for environmental issues and its role as a computational benchmark system for higher actinides. Direct structural information on the coordination of uranyl in aqueous solution has been obtained mainly by extended X-ray absorption fine structure (EXAFS) measurements,74-76 whereas X-ray scattering studies of uranium and actinide solutions are more rare.77 Various ab initio studies of uranyl and related molecules, with a polarizable continuum model to mimic the solvent environment and/or a number of explicit water molecules, have been performed.78-82 We have performed a structural investigation of the carbonate system of dioxouranyl (VI) and (V), [U02(C03)3]4- and [U02(C03)3]5- in water.83 This study showed that only minor geometrical rearrangements occur upon the one-electron reduction of [U02(C03)3]4- to [U02(C03)3]5-, which supports the reversibility of this reduction. 

Development and testing of a new porous crystalline matrix (Gubka) for stabilizing actinide solutions. Materials Research Society Symposium Proceedings, 608, 637—642. 

S. Ahrland, J. O. Liljenzin and J. Rydberg, Actinide Solution Chemistry , in Comprehensive Inorganic Chemistry ,... 

Since the 1960s, considerable efforts have been devoted worldwide to develop viable An(III)/Ln(III) separation systems, either by liquid-liquid extraction, precipitation, or ion-exchange chromatography. These systems have been regularly reported in comprehensive reviews covering various issues of actinide and lanthanide separations, such as the basics of actinide solution chemistry in aqueous/... 

Wai, C. M. (1997) Separation of lanthanides and actinides with ionizable crown ethers, Recent Progress in Actinides Separation Chemistry, Proceedings of the Workshop on Actinides Solution Chemistry, WASC 94, Tokai, Japan, Sept. 1-2, 1994, 81-94. 

LANTHANIDE AND ACTINIDE SOLUTION CHEMISTRY AS STUDIED BY TIME-RESOLVED EMISSION SPECTROSCOPY... 

This chapter deals with experimental TRES results and theoretical approaches that are relevant to the question of lanthanides and actinides solution chemistry. In this sense, this chapter... 

This volume of the Handbook illustrates the rich variety of topics covered by rare earth science. Three chapters are devoted to the description of solid state compounds skutteru-dites (Chapter 211), rare earth-antimony systems (Chapter 212), and rare earth-manganese perovskites (Chapter 214). Two other reviews deal with solid state properties one contribution includes information on existing thermodynamic data of lanthanide trihalides (Chapter 213) while the other one describes optical properties of rare earth compounds under pressure (Chapter 217). Finally, two chapters focus on solution chemistry. The state of the art in unraveling solution structure of lanthanide-containing coordination compounds by paramagnetic nuclear magnetic resonance is outlined in Chapter 215. The potential of time-resolved, laser-induced emission spectroscopy for the analysis of lanthanide and actinide solutions is presented and critically discussed in Chapter 216. 

Lanthanide and Actinide Solution Chemistry Studied by Time-Resolved Emission... 

Lanthanide and actinide solution chemistry as studied by time-resolved emission spectroscopy 465... 

Donnan dialysis and diffusion dialysis techniques are used [30] to deacidify and concentrate actinide bearing acidic solutions. Near complete deacidification could be achieved from 8 M nitric acid solutions with a high decontamination factor for the actinides. With cation-exchange membranes, the deacidification is accomphshed by the build up of neutralized salt in the feed. With an anion-exchange membrane, the feed acidic solution is deacidrfied free of salt buildup. By superimposing direct osmosis with free deacidiflcation, it was simultaneously possible to concentrate the deacidified actinide solution [30]. 

With no supporting fundamental data, reactor technologists concerned with the chemistry of reactor fuels could merely speculate on the behavior of the actinide solutions should they be exposed to electromagnetic radiation. Then as fuel reprocessing became a topic of much interest during the past decade, the concern of possible photochemical activity began to occupy the thoughts of some researchers. 

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