Hydrophilic contributions to thermodynamic partition functions of some metal acetylacetonates and monothioacetylacetonates have been calculated by subtracting from the experimental quantities the contributions due to hydrophobic hydration of the chelate in the aqueous phase and to its interactions with the organic phase. These contributions have been evaluated with the use of a simple model describing solubility of hydrocarbons in water, and the theory of regular solutions, respectively. The results obtained are discussed in terms of different hydration of the chelates in their outer coordination sphere and—for coordinatively unsaturated chelates—also in the inner coordination sphere. Especially important are the effects due to replacing oxygen atoms in the acetylacetonate ligands by sulfur, strongly enhancing the extraction of metal chelates.
Authors:A. Bilewicz, R. Dybczynski, and J. Narbutt
Selectivity of hydrous titanium dioxide as an ion exchanger for alkali metal and tetraalkylammonium ions, has been studied using radioactive indicators:22Na and137Cs. The equilibrium distribution of trace amounts of sodium and cesium ions between the exchanger and aqueous solutions containing macroamounts of other univalent cations was studied over the temperature range of 15 to 80°C. The selectivity sequence in slightly acidic and neutral solutions is as follows: (CH3)4N+<Li+<Na+<K+<Rb+<Cs+, whilst in alkaline solutions it is partly reversed. From the values of selectivity coefficients and the calculated values of thermodynamic functions one can infer that whilst hydrated ions are exchanged from acidic and neutral solutions, from alkaline solutions partly dehydrated ions enter the exchanger phase. The existence of ion-sieve effects for the univalent cations studied was observed, and the presence of at least two kinds of hydroxyl functional groups of different acidities is postulated. Ion exchange reactions of alkali metal cations on hydrous titanium dioxide, as well as the selectivity sequences observed have been interpreted on the basis of EISENMAN theory.
Authors:A. Bilewicz, R. Dybczynski, and J. Narbutt
The adsorption of transition metal cations on hydrated titanium dioxide in complexing ammonia and amine solutions has been studied as a function of ammonia (amine) concentration. The relationships between the distribution coefficients and ammonia concentration as well as the effects of various amines on sorption of transition metals indicate that a coordinate bond is formed between the metal ions and the hydroxy groups of the sorbent. The distribution coefficients of silver(I) and cobalt(III), which form strong ammonia complexes in aqueous solutions, decrease with increasing concentration of ammonia already at concentrations exceeding 10–3. mol·dm–3. Cations of zinc, manganese and mercury which form much weakerammonia complexes do not exhibit any effect of ammonia concentration in the whole range investigated. In the case of sorption of macroamounts of ammonia or amine complexes of silver, the molecular sieve effect plays an important role. The differences in the affinity of hydrated titanium dioxide for ammonia solvates of various transition metal ions can serve as a tool for effective separation of these ions in ammonia solutions.
Properties and applications of composite ion exchangers developed in this Institute are described. The new sorbents consist of a selective inorganic ion exchanger, e.g., hexacyanoferrate of transition metals or hydrated antimony pentoxide, firmly incorporated into a resin matrix, e.g., phenol-formaldehyde, of various shapes. The composites have proved to be effective adsorbents for radionuclides of cesium, sodium, francium, elements 104 and 105, and some others. The sorbents were successfully tested as filter fillers for radiocesium removal from liquid radioactive wastes and from other solutions encountered in nuclear technology. They were also applied in radiochemical studies and in nuclear activation analysis.
Authors:J. Narbutt, J. Olza, Z. Przybyłowicz, and S. Siekierski
Extractive purification of boric acid from radioactive corrosion and fission products dissolved in aqueous solutions modelling
nuclear reactor coolants has been studied. Aliphatic 1,3-diols containing 8 and 9 carbon atoms per molecule were used as extractants
fro boric acid. The behaviour of some representative corrosion and fission products as well as various factors affecting their
distribution between the organic and aqueous phases have been investigated under the conditions of boric acid extraction.
Conditions for the effective separation of boric acid from most of the radioactive contaminants are presented.
Authors:J. Narbutt, J. Siwiński, B. Bartoś, and A. Bilewicz
Recent work directed towards synthesizing and exploring new effective sorbents for radiocesium removal from primary coolants of pressurized water nuclear reactors of the WWER type is presented. Various sorbents synthesized on the basis of titanium hexacyanoferrate are compared with one another from the point of view of their sorption efficiency and stability. The uptake of137Cs from solutions containing boric acid and millimolar quantities of ammonium and potassium ions was studied under conditions simulating the process of purification of the coolant bled from the primary circuit of the reactor. A composite-type sorbent was selected of good mechanical properties and negligible solubility, efficiently decontamining large amounts of the solution (considerably exceeding 104 bed volumes) in the course of the column process.
Authors:H. Polkowska-Motrenko, W. Żmijewska, B. Bartos, A. Bilewicz, and J. Narbutt
A composite ion exchanger containing hydrated antimony pentoxide (HAP) in polystyrene-divinylbenzene matrix has been prepared. Its sorption properties with respect to Na, As, Au, Cd, Cu, Ga, Hg, In, K, La, Mn, Mo (Tc), Pd, Pt, Sb, W and Zn have been examined. Sodium is quantitatively retained on the sorbent from 8M HCl solution as well as from a mixture of conc. H2SO4+ conc. HNO3+H2O (1+1+2). As, W, Cd and Sb are partially retained, while the remaining elements are not retained and can be quantitatively eluted. The composite ion exchanger is stable to oxidizing acid media and it can be directly applied to separation of24Na from mineralizates of neutron-irradiated biological materials.