DE102008064682B4 - Anionic borane polymer, as well as its use and preparation - Google Patents

Abstract

Cation exchanger containing a borane polymer according to the following general formula (I) or (II): [B _h H _h-2-km X _{1 + k} Y _m ] _n ^2n- (I) or [CB _{h-1 h-2 H-km} X _{1 +} Y _{k m] n} ^{n- (II)} in which
X is selected from the group consisting of: O, S, SO, SO ₂ , S ₂ , S (O) S, S (O) S (O), POR, PR ₃ , POR ₃ where R = F, Cl, Br, I, H, C ₁ -C ₄ -alkyl, aryl, wherein the aryl having one or more substituents OH, OR, SO ₃ H, COH, CO ₂ H, Br, Cl, F, CN, NH ₂ CF ₃ , NO ₂ , methyl, ethyl is substituted;
Y is selected from the group consisting of: OH, F, Cl, Br, OR, SH, SR, SR ₂ , SCN, CO, COR, CO ₂ R, NH ₂ , NH ₃ , NR ₃ , where R = C ₁ C ₄ alkyl, aryl, wherein aryl having one or more substituents OH, OR, SO ₃ H, COH, CO ₂ H, Br, Cl, F, CN, NH ₂ , CF ₃ , NO ₂ , C ₁ C ₄ alkyl substituted;
h = 10 or 12;
k is a real number from 0 to 2;
m is a real number from 0 to 10, if h = 12, ...

Description

The present invention relates to a cation exchanger according to claim 1.

Although it has been the focus of intensive research for decades, the question of disposal of radioactive waste has so far been solved unsatisfactorily. The development of new technical, chemical and physical processes for the treatment of radioactive waste and the prevention of ionizing radiation is still in the foreground.

The largest part of radioactive waste is produced by the uranium mining, where the waste is stored without treatment in the vicinity of the respective uranium mine. Although the residues from the ore production itself are stored on site in special ponds separated by dams, a treatment is also not planned.

Radioactive waste, which is disposed of in an orderly manner for reasons of radiation protection, comes from nuclear power plants, from the reprocessing of spent fuel elements, as well as from the use of radioactive substances in medicine, industry and research. This involves solid, liquid or gaseous radioactive waste, which must be prepared for disposal. Radioactive waste can be divided into low active waste (LAW), medium active (MAW), and high active waste (HAW) waste. In addition, a distinction is made according to heat-generating and non-heat-generating waste, with usually only the highly radioactive waste developing heat.

In nuclear power plants, for example, on the one hand, industrial waste (in the first instance not heat-generating) and, on the other hand, spent fuel (heat-generating) are produced. The radioactive operational waste is generated by cleaning the system, by cleaning the cooling circuit, the water to be released from control areas and the air. In particular, solid combustible and pressable waste is involved in cleaning the system. These raw waste is greatly reduced in volume by drying, burning or pressing. To clean the cooling circuit z. B. used in pressurized water reactors ion exchange resins and filter cartridge inserts. Evaporation plants, centrifuges and ion exchangers (filters) are used to clean the water to be dispensed. Filters are used for air purification. Subsequently, the volume-reduced radioactive waste is transferred or conditioned in a chemically stable state which is not or only slightly soluble in water. This means an embedding in concrete or bitumen and a subsequent, in accordance with the requirements of vans and repositories packaging in steel or concrete containers.

In a boiling water reactor with an electrical output of 1300 MW, approximately 286 m ³ raw waste quantities with negligible heat generation accrue per year of operation (excluding the spent fuel elements), of which 7 m ^{3 are} ion exchange resins from the coolant purification. These are usually flammable organic ion exchangers, which are already significantly impaired in their function after a radiation dose of> 10 ⁶ Gray and must be replaced. After appropriate treatment and conditioning results in a quantity of about 50 m ^{3 of} radioactive operational waste with negligible heat generation.

The amount of waste from the disposal of the annual spent fuel of the power plant is dependent on the disposal: in the direct disposal of the spent fuel 45 m ³ heat-generating waste accumulate, with heat-generating waste generally melted for final disposal in glass or ceramic and packed in stainless steel molds become. In a reprocessing, which again requires the use of cation exchangers, etc., arise 10 m ³ radioactive operating waste with negligible heat generation and 3 m ³ heat-generating waste.

Since 1984, the Federal Office for Radiation Protection (www.bfs.de) annually determines the stock of radioactive waste in the territory of the Federal Republic. Thus, according to a list, without consideration of disused fuel, at the end of 2005 a total of about 117350 m ³ residues with negligible heat generation (treated and untreated) and about 1850 m ³ heat-generating radioactive residues (both treated and untreated) were present. The average amount of treated (conditioned) waste with negligible heat generation was approximately 4500 m ³ per year from 1984 to 2005. The forecasts currently assume that by 2040 about 277,000 m ^{3 of} conditioned waste with negligible heat generation and about 24,000 m ^{3 of} conditioned heat-generating waste will be generated. In view of these figures, it is of great importance to continue the development of effective methods for the treatment of radioactive waste.

Looking at the group of waste producers, it appears that in 2005 the nuclear industry produced 8.2% and nuclear power plants in operation 16.6% of the negligible heat-producing waste. Research institutions accounted for 44.7% of the waste and medicine accounted for 0.5% of negligible heat-generating waste. Nuclear chemistry or radiochemistry thus represents a broad field of research, and in addition to energy generation numerous other applications are possible. The knowledge gained about the properties of radioactive nuclides is used in many areas of applied research, industrial production and medical diagnosis and therapy, such as radiochemistry and radiopharmacology.

If one element is to change into another, the number of core protons must be changed. This happens voluntarily in nature in a number of elemental nuclides. This is the case for all nuclides with a higher atomic number than that of bismuth, since these are unstable and decay radioactively. However, elemental transformation can be enforced in virtually all nuclides by including protons in the nuclide core or bombarding nucleons with projectiles (elementary particles or atomic nuclei) (artificial elemental transformation). Thousands of such induced nuclear reactions have already been investigated today. In addition to the natural nuclides (263 stable and 70 radioactive), around 2000 artificial radioactive nuclides were recovered.

The exact investigation of the properties of a particular nuclide and its potential application, for example in nuclear medicine, are associated with high purity requirements. For quantitatively and effectively separating smaller amounts of radionuclides as needed in research and medicine, fractional crystallization, precipitation or co-precipitation, electrolysis, distillation, solvent extraction, chromatography and ion exchange are the most commonly used methods (Lieser, KH, Nuclear and Radiochemistry Fundamentals and Applications, second revised edition, Wiley-VCH, 2001).

Ion exchange processes have now found wide application in nuclear medicine. Commercial ion exchangers show a relatively low selectivity. Higher selectivity is achieved through the use of organic ion exchangers modified with specific chelated groups adapted to the problem. Organic ion exchangers with good selectivity are produced on the basis of polystyrene, cellulose or other matrix substances. The selectivity can also be improved by adding complexing agents such as lactic acid or α-hydroxybutyric acid to the solution. The disadvantages here are: a) breakage of the matrix-functional group bond by ionizing radiation and decrease in capacitance; b) limited stability in strong acids / bases and organic solvents. Inorganic ion exchangers, which are likewise used for the selective purification of nuclides, may be hydrogenated oxides (Al ₂ O ₃ .xH ₂ O, SiO ₂ .xH ₂ O, TiO ₂ .xH ₂ O, ZrO ₂ .xH ₂ O, SbO ₂ · XH ₂ O), salts of certain acids (titanium and zirconium phosphates, molybdenum hexacyanoferrate), salts of heteropolyacids (ammonium molybdenum phosphate) or clay minerals. Many ionic inorganic compounds (BaSO ₄ , AgCl, CuS) also show ion exchange properties and good selectivity. A disadvantage of inorganic ion exchangers is their slow equilibration due to the low mobility of the ions in the crystal lattice. Furthermore, the use is limited to ions that fit into the crystal lattice structure.

Smaller amounts of radionuclides, such as those required in research and medicine, can be generated in nuclear reactors, cyclotrons or nuclide generators. The bombardment of neutral starting nuclides with slow neutrons in a nuclear reactor leads to unstable nuclei with neutron excess. Nuclear fission is also possible whose products are radioactive. In the cyclotron, the bombardment of the starting nuclides with charged particles (protons, deuterons, α-particles or heavy ions) leads to nuclides with proton excess. The nuclides produced in nuclear reactors or cyclotrons can in turn serve as so-called mother nuclides in so-called nuclide generators.

Gamma radiation arises as a consequence of previous radioactive decay (eg, α or β decay) of an atomic nucleus. The nucleus remaining after decay, the daughter nucleus, is usually in an excited state, with γ radiation being emitted during the transition to a less excited state or ground state. The half-life of the gamma transitions is usually very short (far less than one second). The excited atomic nuclei, which decay with half-lives of seconds, minutes, or even longer, are called metastable or core isomers. While the high ionization intensity of α- or β-radiation is desirable in therapeutic measures, for example in nuclear medicine, gamma radiation is preferred in nuclear medicine diagnostic procedures, the half-life of which should be relatively long (minutes to hours).

For the production of short-lived gamma emitters suitable for in vivo diagnostics, it is particularly advantageous to use nuclide generators to which the desired short-lived radionuclides can be removed immediately before they are used. Such a nuclide generator consists of a chromatography column to whose matrix a longer-lived radioactive precursor (parent nuclide) is fixed. The daughter nuclide, which is continuously replicated from the parent nuclide by radioactive decay, can be repeatedly eluted with a suitable solution while leaving the parent nuclide on the column. For adsorption of the parent substance in the generator inorganic carrier substances are often used because they have a fairly good chemical and radiation-chemical resistance. Between two elutions, a certain recovery time of the generator is required, in which enough daughter nuclide can emulate. In practice, however, a period of 4 to 5 half-lives of the daughter nuclide is sufficient.

The ⁹⁹ Mo / ^99m Tc generator is the most widely used radionuclide generator in nuclear medicine. Metastable ^99m Tc is by far the most important element for imaging (scintigraphic) nuclear medicine diagnostic procedures due to the half-life of 6 hours and its ability to attach to many active biomolecules. For this purpose, organic ligands with a high tendency to bind to cells of the organ to be examined, or monoclonal antibodies, proteins of the immune system, which attach to selected antigens of tumor cells are coupled to ^99m Tc and administered intravenously. In this way, a variety of organs can be examined.

Other generators used in nuclear medicine are the Zn ⁶² / Cu ^{62 68} Ge / ⁶⁸ Ga, ⁸² Sr / ⁸² Rb and ¹¹³ Sn / In ^11m generators. ⁶² Cu, ⁶⁸ Ga and ⁸² Rb are important as positron emitters in positron emission tomography (PET), another imaging technique. Some radionuclide generators have found application in chemical laboratories and in industry. An example of this is the ¹³⁷ Cs / ^137m Ba generator. ^137m Ba has a relatively short half life (2.55 min) and changes to the stable ground state ¹³⁷ Ba by the emission of γ radiation. The γ-radiation can be easily detected and measured. The long half-life of the parent nuclide ¹³⁷ Cs (t _1.2 = 30.17 a) makes it possible to use this generator over a long period of time. A prerequisite for this is that the ¹³⁷ Cs is bound so tightly that its migration can be ruled out during the time the generator is being used and only ^137m Ba is eluted. In addition, the wearer must remain stable over the long term. In one of the conventional processes, ¹³⁷ Cs, which form as fission products in nuclear reactors, are fixed on hexacyanoferrate thin films, which are generated on the surface of small pieces of metal (Fe, Mo). This is a relatively complex process and as a result of the decomposition of the cyano complexes, caused by the ¹³⁷ Cs radiation, very toxic products are formed. Furthermore, it is possible to use both an aluminum and molybdenum-containing polyoxometalate (Dhara S. et al., Radiochim Acta 2007, (95), 297-301) or a polymer modified with chelating amide groups (Maji et al. , Radiochim Acta 2007, (95), 183-186). However, organic polymers show lower stability to radiation compared to inorganic compounds.

Ion exchangers can thus be used in many areas of radiochemistry. In addition to being used in the treatment of radioactive waste and in the production of radionuclides for nuclear medicine, they can also be used in radioanalytical chemistry to concentrate ions or separate certain elements. In nuclear medicine, in addition to use in nuclide generators, ion exchangers can also be used to isolate radionuclides from irradiated targets or fission products, or for final purification.

In principle, cation exchangers must meet two requirements in radiochemistry: they must have a high stability to ionizing radiation and they must have a high selectivity, since the radionuclides to be separated are often only present in orders of magnitude smaller amounts compared to the stable elements. In addition, contamination with, for example, long-lived radionuclides already has great effects, as their relative concentration increases with time. For example, if the impurity concentration of ⁹⁰ Sr after a separation of ¹⁴⁰ Ba is only 0.1%, the ⁹⁰ Sr activity will increase to 11.5% within three months in the ¹⁴⁰ Ba sample due to radioactive decay. For all internal medical applications and especially for diagnostic purposes, the purity of the radionuclides is of paramount importance. The absence of long-lived radioactive contaminants, in particular α-emitters or high-energy β-emitters must always be ensured.

The present invention relates to a novel polymer or cation exchanger which is suitable for nuclear and nuclear medical applications, wherein the polymer is composed of borane polyhedra. Hydrides of the boron are characterized by their unique bonding conditions, in which electron deficiencies allow chemical bonds of three atoms. In contrast to In the case of boranes, hydrocarbons do not form double bonds, but rather mostly symmetrical cage-like compounds derived from polyhedra. The geometry of these borane structures is determined by the ratio of the number of skeletal electrons to the number of skeletal atoms. Higher boranes than diborane are formed (formally) by the assembly of the same or different, non-viable compounds B _m H _{m + 2} into a borane molecule, whereby the borohydride groups B _n H _{n + 2} (closo-boranes), B _n H _{n +4} (nido-boranes), B _n H _{n + 6} (arachno boranes) and B _n H _{n + 8} result (hypho boranes).

In closo-boranes, which have hitherto been known only as anionic form B _n H _n ^2- as boranates, all corners of a polyhedron are occupied by boron atoms. A total of 4n + 2 electrons are split so that 2n electrons form n BH bonds and 2n + 2 electrons hold the bar polyhedron composed of n boron atoms with a combination of BB two-center bonds and BBB three-center bonds. In the nido-Boranen all corners are occupied except for one, in the arachno-Boranen all but two corners are occupied and occupied in the hypho-Boranen all to three corners. One or more boron atoms of the boranes and boranates can be replaced by atoms of other elements. For example, carba-, sila-, aza-phospha- thia- or metallaboranes are known. They also belong to the electron deficiency compounds and are derived from them by the replacement of BH or BH ₂ groups. In the case of heteroboranes, a distinction is likewise made between closonido, arachno and hypho heteroboranes.

The closo-boranates B _n H _n ^2- (n = 6-12) and the heteroboranes derived therefrom are particularly interesting because they contain closed polyhedral boron skeletons with a quasi-aromatic bond character. This three-dimensional aromaticity, which is comparable to that of fullerenes, gives them a special stability. In addition, some nido- and arachno-boranes also form stable cage compounds and decompose only at high temperatures. Certain nido anions (for example nido-C ₂ B ₉ H ₁₁ ^2- ) are also known to form stable sandwich complexes with metal cations.

The closo-boranates have been extensively researched for use in the treatment of cancers. Treatment therapies such as Boron Neutron Capture Therapy (BNCT) are based on the selective uptake of a ¹⁰ B-containing substance into tumor cells and subsequent irradiation of these cells with thermal (slow) neutrons, involving the nuclear reaction ¹⁰ B (n, α) ⁷ Li induce. The resulting α particles and Li nuclei have a short range and selectively induce irreparable damage in the tumor cell DNA. It makes sense to attach a tumor affinity peptide whose receptor is overexpressed on the tumor surface or in the cell nucleus via a linker to a boranate such as B ₁₂ H ₁₂ ^2- . Boronates are particularly well suited for use in boron neutron capture therapy because of their high number of boron atoms. Although initial promising results for the treatment of brain tumors are available, this approach is still in development.

Boranates have also been investigated for use in liquid-liquid extraction, which is also used to treat radioactive waste. Thus, cobaltabis (dicarbollide) (COSANe) and its derivatives have been known for some time (Vinas C. et al., Chem Commun 1998, (2), 191-192; Mikulasek L., et al., Chem Commun 2006 (38)). 4001-4003). Cobaltabis (dicarbollide) consist in the simplest case of two nida-1,2-C ₂ B ₉ H ₁₁ ^2- Carbaboranaten that coordinate a Co ³⁺ cation. Since the goal is to remove the radioactive cations as completely as possible from an aqueous solution, the COSANes were variously derivatized with hydrophobic residues. In addition, attempts have been made to improve selectivity by covalently attaching certain molecules to the Carbaborank cages, which can also be used by themselves for extractions, such as crown ethers, calixarenes or organic phosphines. These compounds typically have a partition coefficient for certain lanthanides and actinides of about 100 in the presence of 0.01 M HNO ₃ and only about 0.05 in the presence of 3.0 M HNO ₃ .

There are now also examples of the use of closo-boranates, in particular B ₁₂ H ₁₂ ^2- , for the treatment of radioactive waste in a liquid-liquid extraction process (Naoufal et al., Mediterranean Conference for Environment and Solar, 2000, 40). 44, Bernard R. et al., J. Organomet Chem 2002, (657) 83-90). The derivatization principles applied to it correspond to those already mentioned above. In the meantime, a series of B ₁₂ H ₁₂ ^{2- have been} prepared which contain covalently bonded radicals, whereby both the hydrophobicity and the selectivity can be increased. The distribution coefficients of the boranates are similar to those of the COSANes. Thus, binding capacity of the dissolved closo-boranates in acidic environments is also severely limited. Another disadvantage is the complex regeneration of radionuclide-loaded boronates, which are obtained during a liquid-liquid extraction. Their presence as a solid phase or as a resin would greatly facilitate the regeneration process and, above all, increase the stability against strong acids and radiation.

Starting from the prior art, it is the object of the present invention to provide a radiation-resistant and acid-stable polymer or a cation exchanger and their use in nuclear engineering and nuclear medicine.

The solution of this object is achieved by a cation exchanger according to claim 1.

In particular, the present invention relates to an anionic borane polymer according to one of the following general formulas: [B _h T _h-2-km X _{1 + k} Y _m ] _n 2 ^n- (I) or [CB _h-1 H _h-2-km X _{1 + k} Y _m ] _n ^n- (II); in which
X is selected from the group consisting of: O, S, SO, SO ₂ , S ₂ , S (O) S, S (O) S (O), POR, PR ₃ , POR ₃ where R = F, Cl, Br, I, H, C ₁ -C ₄ -alkyl, aryl, wherein the aryl having one or more substituents OH, OR, SO ₃ H, COH, CO ₂ H, Br, Cl, F, CN, NH ₂ CF ₃ , NO ₂ , methyl, ethyl is substituted;
Y is selected from the group consisting of: OH, F, Cl, Br, OR, SH, SR, SR ₂ , SCN, CO, COR, CO ₂ R, NH ₂ , NH ₃ , NR ₃ , where R = C ₁ C ₄ alkyl, aryl, wherein aryl having one or more substituents ON, OR, SO ₃ H, COH, CO ₂ H, Br, Cl, F, CN, NH ₂ , CF ₃ , NO ₂ , C ₁ C ₄ alkyl substituted;
h = 10 or 12;
k is a real number from 0 to 2;
m is a real number from 0 to 10 when h = 12, and a real number from 0 to 8 when h = 10;
n is a natural number of> 10 ⁹ , preferably polymerized crystals with a diameter of about 1 micron or greater.

The anionic borane polymer consists of bridged borane polyhedra, where X denotes the functional units bridging borane polyhedra; Y indicates the nature of the substituents substituting hydrogen atoms within the polyhedron.

The coefficient h defines the number of skeletal atoms of a polyhedron, where k indicates the degree of cross-linking of the polyhedron. On the basis of the coefficient m, the degree of substitution of individual hydrogen atoms of the borane polyhedra is defined, where n is the number of repeating units in the polymer core.

Individual boron atoms of the polyhedral skeleton can be substituted with a carbon atom, whereby the negative charge of a repeating unit is decreased by one. A BH group is replaced by a CH group.

The borane polymer can be used in nuclear engineering for the treatment of radioactive waste and in nuclear medicine for the purification of radionuclides. The borane polymer can be used as a cation exchanger according to a chromatographic principle and is characterized by a high stability to ionizing radiation. Furthermore, the borane polymer has a high ion exchange capacity paired with a high selectivity, especially for single-charged cations of heavy metals, which properties are retained even at very low pH values and at a very high excess of conventional monovalent cations (Na ⁺ and K ⁺ ).

For the purposes of the present invention, the anionic borane polymer of the present invention is referred to as BOPOR (borane polymer resin).

It is preferred that the borane polymer is composed of closo-boranes. As already mentioned above, boranes, the corners of which are all occupied, are particularly stable, so far closo-boranes are known in the anion form and thus as closo-boranates or in the form of charged or neutral derivatives which are soluble in water or organic solvents , The resulting number of skeletal electrons of the boranates allows stable quasi-aromatic bonds in the polyhedron. The negative charge of each Boranatpolyeders is delocalized over the entire cage.

It is further preferred that the number of skeletal atoms of a polyhedron given by the coefficient h is 10. It is also preferred that the number of skeletal atoms of a polyhedron given by the coefficient h is 12. The boranates B ₁₀ H ₁₀ ^2- and B ₁₂ H ₁₂ ^2- are extremely stable to acids and bases and are not attacked even at 100 ° C. The same applies to their heteroatom derivatives. The alkali salts M ₂ B ₁₀ H ₁₀ and M ₂ B ₁₂ H ₁₂ decompose thermally in the absence of oxygen only above 600 ° C. The acids underlying the ions [H ₃ O] ₂ [B ₁₀ H ₁₀ ] and [H ₃ O] ₂ [B ₁₂ H ₁₂ ] are very strong acids, so that the polymers derived from them are effective strongly acidic cation exchangers.

It is preferred that the borane polymer contain as counterions any, exchangeable cations. These may be, for example, metal cations, cation complexes or organic cations. It is further preferred that the counterions are oxonium ions. The cations or counter ions of the borane polymer can be exchanged for other cations. It is preferred that oxonium ions of the borane polymer be exchanged for other cations.

It is also preferred that the borane polymer additionally contains water molecules. It is further preferred that the water molecules surround the cations. It is particularly preferred that the borane polymer contain metal cations surrounded by water molecules, facilitating cation exchange between solid and liquid phases.

A preferred embodiment of the borane polymer of the present invention is one which has oxonium ions as counterions, ie, is in the H ⁺ form, and the composition (H ₃ O) _2n [B ₁₂ H _8.44 (SO) _1.716 Cl _0.844 ] _n · 5nH ₂ O having.

This preferred embodiment is characterized by a high stability to ionizing radiation, wherein the selectivity for certain cations depends on their charge and radius. This allows group separations of single, double and triple charged cations. The selectivity is retained even under strongly acidic conditions. The preferred embodiment is further characterized in that it can be prepared in simple reaction steps.

In particular, the present invention relates to a cation exchanger containing an anionic borane polymer according to the invention.

It is preferred that the cation exchanger show a different selectivity for cations, the selectivity depending on the charge and radius of the cations. It is therefore preferred that the selectivity increase in the order M ²⁺ <M ³⁺ <M ⁴⁺ . It is also preferred that the selectivity increase in the order M _l ⁺ <M ²⁺ <M ³⁺ <M ⁴⁺ <M ⁵⁺ where M _l ^{+ are} monovalent cations of the lighter metals (eg Li ⁺ , Na ⁺ , K ⁺ ) and M ₅ ^{+ are} monovalent heavy metal cations (eg, Cs ⁺ , Tl ⁺ , Ag ⁺ ). The selectivity for monovalent cations is strongly dependent on the ionic radius and increases in the order Li ⁺ ≈ Na ⁺ <K ⁺ <Rb ⁺ <Cs ⁺ ≈Tl ⁺ Ag ⁺ . For this purpose, for the preferred embodiment (H ₃ O) _2n [B ₁₂ Ha _8.44 (SO) _1.716 Cl _0.844 ] _n · 5nH ₂ O the distribution coefficient (K _D ) for various ions in nitrous or hydrochloric acid aqueous solution was determined, including Na ⁺ , Cs ⁺ , Ag ⁺ , Tl ⁺ , Mg ²⁺ , Ca ²⁺ , Sr ²⁺ , Ba ²⁺ , Ra ²⁺ , Pb ²⁺ , UO ₂ ²⁺ , Y ³⁺ , Ac ³⁺ , Eu ³⁺ , Yb ³⁺ , Lu ³⁺ , Th ⁴⁺ In particular for Cs ⁺ , Ag ⁺ Tl ⁺ and Pb ²⁺ BOPOR shows an exceptionally high selectivity (Table 1). It is obvious to a person skilled in the art that, for example based on distribution coefficients, the optimum separation or elution conditions can be determined in a simple manner and without unreasonable labor.

It is preferred that the cation exchanger is stable over a pH range of 0 to 14. It is particularly preferred that the cation exchanger is stable in the strongly acidic range, including in strongly oxidizing acids, while retaining its ion exchange capacity. For example, about 96% of the fuel used for processing consists of unused uranium and 1% plutonium, with both substances in principle being able to be processed into new fuel elements. The remaining 3% are fission products and higher actinoids and make up the actual radioactive waste. After the fuel elements are comminuted in the reprocessing plant, the fuel is extracted from the sections with hot nitric acid. With the help of tributyl phosphate diluted with kerosene, the uranium and plutonium nitrates are extracted, while the nitrates of the cleavage products and actinoids remain in the nitric acid aqueous phase. A conceivable strategy for further disposal and Processing consists of converting these nuclides into more short-lived nuclides by bombardment with neutrons or other particles (transmutation) in order to store as few as possible of these long-lived radionuclides in repositories. For this purpose, the nuclides to be converted must first be separated, for which purpose the selective cation exchanger according to the invention, which is stable at low pH values and whose ion exchange capacity is not significantly influenced by low pH values, can be used. Also conceivable in the reprocessing is an additional separation of the resulting from nuclear fission precious metals such as ruthenium, rhodium and palladium, but this is not yet practiced. For this purpose, the cation exchanger according to the invention is also suitable.

As already mentioned, for the preferred embodiment (H ₃ O) _2n [B ₁₂ H _8.44 (SO) _1.716 Cl _0.844 ] _n , · 5nH ₂ O the distribution coefficient for different ions in nitrous or hydrochloric acid aqueous solution was determined. Although the K _D values sink in an acidic environment, the K _D value for Cs ⁺ ions in the presence of about 12 M acid, for example, is still 10 ³ , with even higher values for Ag ⁺ and Tl ⁺ were. Considering K _D values of the compounds mentioned in the introduction, which are used in the prior art in a liquid-liquid extraction, it is clear that these compounds have very unsatisfactory distribution coefficients even in the presence of 1-3 M acid , The cation exchanger of the present invention is thus distinguished by an excellent acid stability, wherein the selectivity, recognizable by the high K _D values, is maintained even at very low pH values.

It is preferred that the cation exchanger is stable to ionizing radiation. During the reprocessing of radioactive waste, it is necessary that the ion exchangers used for this purpose are stable to the highest possible radioactive radiation doses while retaining their ion exchange capacity. The ion exchange capacity of (H3O) 2n [B ₁₂ H8,44 (SO) 1,716Cl0,844] _n · 5NH ₂ O was measured before and after irradiation with a dose of 5.9 x 10 ⁶ Gy or 1 x 10 ⁷ Gy determined (Table 2). The integral dose of 5.9 x 10 ⁶ Gy did not alter the ion exchange capacity, while the integral dose of 1 x 10 ⁷ Gy resulted in a 10% decrease in ion exchange capacity. The stability of BOPOR to ionizing radiation is thus higher than the organic ion exchange resins. Ionizing radiation of the order of 10 ⁵ -10 ⁶ Gy significantly changes the properties of synthetic organic ion exchange resins. Zeolites show a decrease in their ion exchange capacity after an integral dose of 5 × 10 ⁷ -10 ⁸ Gy. It can thus be concluded that the stability of BOPOR to ionizing radiation is comparable to that of zeolites.

It is preferred that the cation exchanger loaded with H ₃ O ⁺ exhibits a color change when charged with metal ions. A special feature of BOPOR is the dependence of its color on its cationic form. The particular embodiment (H ₃ O) _2n [B ₁₂ H _8.44 (SO) _1.716 Cl _0.844 ] _n · 5nH ₂ O, for example, has a black color in the H ₃ O ⁺ form. If this resin is loaded with metal cations, it will turn a grayish brown to light yellow color. The color changes back to black after the resin is returned to the H ₃ O ⁺ form by washing with acid. Thus, the color can be used to quickly and easily determine the state of charge of BOPOR and to determine the time when regeneration is necessary.

Furthermore, BOPOR is characterized by having good ion exchange capacity. An average of three independent determinations for the particular embodiment (H ₃ O) _{2 N} [B ₁₂ H _8.44 (SO) _{1.716 0.844} Cl] · 5NH ₂ O yielded a capacity of 5.4 ± 0.2 meq / g (Table 3) and is comparable to the capacity of strong cation exchangers such as polystyrene-based organic resins. In addition, the kinetics of the ion exchange is fast. Furthermore, the cation exchanger is characterized in that it is stable in aqueous, organic and organic aqueous solution.

It is preferred that the cation exchanger is present as a solid which is insoluble in water and organic solvents, in particular resin. This makes it possible to carry out the separation of the cations with the aid of a liquid phase, which is guided along a stationary phase. This is easier to handle than a liquid-liquid extraction. The reprocessing of fuel rods involves relatively large amounts of liquid. If, for example, the splitting elements and actinides are to be further separated and this is done by a liquid-liquid extraction, the intimate mixing of organic and mobile phase must be ensured, which is technically complicated in the case of the large quantities of liquid. The passage of a liquid along a stationary phase or the chromatographic separation of the cations is a technically easier to carry out approach, moreover, the resin, which are stable in aqueous and in organic solvents, can be easily regenerated, as to the resin washed only with acid must become.

It is preferred that the cation exchanger is immobilized on a matrix to increase its mechanical stability.

It is preferred that the cation exchanger is immobilized on a matrix, the matrix comprising, for example, cellulose and / or dextran, and / or silica gel and / or magnetic beads and / or plastic beads, etc.

It is preferred that the cation exchanger be used to selectively separate singly charged cations, preferably heavy single charged cations, from an organic or aqueous or organo-aqueous solution, the solution containing a mixture of singly and multiply charged cations. BOPOR shows particularly high K _D values for heavy single-charged cations, allowing the chromatographic separation of one or more heavy monovalent cations from multiply charged ions, even if a multiply charged cation is present in large excess.

The cation exchanger can generally be used for group separations of singly, twice and three times charged cations in an organic or aqueous or organo-aqueous solution. Since the selectivity of BOPOR increases in the order M _l ⁺ <M ²⁺ <M ³⁺ <M ⁴⁺ <M _s ⁺ , the cation exchanger is therefore suitable for the separation between the groups of cations and also especially within the group of cations charged cations. The selectivity for cations of the transition metals can be increased several times by complex formation.

It is preferred that the cation exchanger be used for the selective separation of doubly charged cations from an organic or aqueous or organo-aqueous solution, the solution containing a mixture of mono-, di- and higher-charged cations.

It is further preferred that the cation exchanger be used for selective separation of triply charged cations from an organic or aqueous or organo-aqueous solution, the solution containing a mixture of mono-, di- and tri-charged cations.

In 1 An example of the separation efficiency is the separation of the divalent cation Ba ²⁺ from the trivalent cation Lu ³⁺ in hydrochloric acid. The mass ratio was Ba / Lu ~ 2300. Ba ²⁺ could be completely eluted with 0.5 M HCl without detection of Lu ³⁺ traces in the eluate. Lu ³⁺ eluted only at concentrations higher than 1 M HCl. This shows that the difference in K _D values by a factor of 10 to 50 allows the selective separation of the triply charged cations from excess dually charged cations.

In the course of determining distribution coefficients of different cations, BOPOR has been found to exhibit exceptionally high selectivity, especially for heavy monoligated cations such as Ag ⁺ , Tl ⁺ , Cs ⁺ . It is thus preferred that the cation exchanger for the selective separation of singly charged Ag ⁺ and / or Tl ⁺ and / or Cs ⁺ ions from an organic or aqueous or organo-aqueous solution containing a mixture of Ag ⁺ and / or Tl ⁺ - and / or Cs ⁺ ions and double, triple and quadruply charged cations is used.

It is further preferred that the cation exchanger also be used to selectively separate lighter singly charged cations such as Li ⁺ , Na ⁺ , K ⁺ from an organic or aqueous or organo-aqueous solution containing a mixture of Li ⁺ and / or Na ⁺ - and / or K ⁺ ions and double, triple and quadruple charged cations, is used. In this case, it means that the light monovalent cations can be eluted first from the cation exchanger of the present invention, while higher charged cations and heavy monovalent cations are still bound to and retained by the cation exchanger.

It is preferred that the cation exchanger be used for the selective separation and / or purification of cations in an organic or aqueous or organo-aqueous radioactive solution. Since the cation exchanger has proved to be stable after exposure to high doses of radiation, it can also be used for the purification of cations which emit ionizing radiation.

It is preferred that the cation exchanger be used to separate and / or purify cationic medicinal radionuclides in an organic or aqueous or organo-aqueous radioactive solution. The use of radionuclides for diagnosis and therapy has already been described in the introduction, with the purity of these radionuclides being particularly stringent become. This can be the separation from a nuclide generator or a final purification, the high selectivity and stability of the resin to ionizing radiation ensuring a high purity and homogeneity of the radionuclides.

It is preferred that the cation exchanger for the selective separation of ⁹³⁷ Cs ⁺ ions from a mixture containing ¹³⁷ Cs ⁺ ions, two, three and four times charged cations, in particular for the selective separation of ¹³⁷ Cs ⁺ ions from a ¹³⁷ Cs ⁺ / ^137m Ba ²⁺ ion mixture in a radionuclide generator. Another preferred use is the use of BOPOR for the separation of Cs ⁺ , which is obtained, for example as a cleavage product in nuclear reactors, from aqueous radioactive waste solutions.

It is preferred that the cation exchanger for the selective separation of ⁹⁰ Sr ²⁺ ions from a mixture containing ⁹⁰ Sr ²⁺ ions, three times and four multiply charged cations, in particular for the selective separation of ⁹⁰ Sr ²⁺ ions of a ⁹⁰ Sr ²⁺ / ⁹⁰ Y ^{3 +} ion mixture in a radionuclide generator. The literature discloses dozens of other mother / daughter nuclide pairs that can be separated in a radionuclide generator. If the formation of any daughter nuclide is accompanied by the corresponding charge change, namely by at least one, the cation exchanger of the present invention can be used for its separation.

Due to the oxidizability of the borane polymer, the cation exchanger loaded with radionuclides can be glazed particularly easily for later disposal.

Moreover, because of its high boron atom content, it is preferred that the cation exchanger be used to absorb neutrons.

Since the purification and / or separation proceeds according to the chromatographic principle, it is preferred that the cation exchanger is used as a column filler material. The use as a pillar filler has the advantage that for a cation exchange only a very simple structure is necessary and the regeneration of the cation exchanger can always be done quickly and easily. It is further preferred that the cation exchanger is used as an ion-selective membrane.

• a) Überführung eines Boransalzes in ein Lithiumboransalz, wobei das Lithiumboransalz Kristallwasser bindet;
• b) in-situ Erzeugung eines Elektrophils durch eine Reaktion von Thionylchlorid mit Kristallwasser;
• c) Heterogene Umsetzung des Lithiumboransalzes mit dem Elektrophil;
• d) Isolierung des Boranpolymers durch Filtrieren und Waschen mit Säure und Wasser.

It is preferred that the borane polymer of the invention is prepared by a process comprising the steps of:

• a) conversion of a borane salt into a lithium borane salt, wherein the lithium borane salt binds water of crystallization;
• b) in situ generation of an electrophile by a reaction of thionyl chloride with water of crystallization;
• c) Heterogeneous reaction of the lithium borane salt with the electrophile;
• d) Isolation of the borane polymer by filtration and washing with acid and water.

It shows:

1 the separation of Ba ²⁺ and Lu ³⁺ with BOPOR on the column (bed volume 1 mL) in HCl. Mass ratio Ba / Lu in the solution was ~ 2300, the flow rate being 0.72 mL / min. The individual fractions were collected at one-minute or two-minute intervals.

embodiments

1. Determination of distribution coefficients (K _D )

wobei A₀ und A_eq Aktivität in der Lösung vor dem Versuch und im Gleichgewicht mit dem Harz, B – Untergrundaktivität, V – Lösungsvolumen, m – Masse der Harzprobe. Die Ergebnisse sind in folgender Tabelle zusammengefasst: Tabelle 1. K_D-Werte für ausgewählte Metallkationen in HCl-Lösung (HCl Konzentration, in M) Ba²⁺ Pb²⁺ Y³⁺ Lu³⁺ Eu³⁺ Cs⁺ Na⁺ Ag⁺ Tl⁺ Th⁴⁺ 0,05 6,5E4 > 1E4 > 2E4 > 5E4 7,4E4 > 4E5 80 > 2E6 > 5E5 > 1E5 0,4 1,5E3 > 1E4 5,9E4 8 8E3 0,6 5,8E2 > 1E4 1,5E4 1,6E4 2,1E4 > 6E5 9E4 2E3 0,8 2,9E2 > 1E4 5,1E3 8,7E3 3,1E4 2,5 1,0 1,8E2 > 1E4 2,5E3 3,9E3 2,5E4 100 1,2 116 > 1E4 1,4E3 1,3E3 2,0E3 > 6E5 2,7E4 1,4 80 > 1E4 7,2E2 1,1E3 1,6 60 > 1E4 4,6E2 4,2E2 6,8E2 1,8 44 > 1E4 3,0E2 2,8E2 1,2E4 2,0 35 > 1E4 2,1E2 1,9E2 3,2E2 2,2 28 > 1E4 1,5E2 136 8,4E3 2,4 22 > 1E4 108 99 1,6E2 > 6E5 2,7 17 7E3 70 63 100 3,0 11 6E3 47 44 69 5,2E3 2E5 SF3 5,0 1E3 6,5 10 2,5E3 10 2E2 3,5E2 For a number of cations the distribution coefficient (K _D ) was determined. For this purpose, ~ 18 ± 0.15 mg of BOPOR were mixed with 1800 μl of the aqueous solution containing a certain acid concentration and the specific activity of the metal cation under investigation. The K _D values were calculated in mL / g according to the following formula

where A ₀ and A _{eq are} activity in the solution before and in equilibrium with the resin, B - subsurface activity, V - solution volume, m - mass of the resin sample. The results are summarized in the following table: Table 1. K _D values for selected metal cations in HCl solution (HCl concentration, in M) Ba ²⁺ Pb ²⁺ Y ³⁺ Lu ³⁺ Eu ³⁺ Cs ⁺ Na ⁺ Ag ⁺ Tl ⁺ Th ^{4 +} 0.05 6,5E4 > 1E4 > 2E4 > 5E4 7,4E4 > 4E5 80 > 2E6 > 5E5 > 1E5 0.4 1,5E3 > 1E4 5,9E4 8th 8E3 0.6 5,8E2 > 1E4 1,5E4 1,6E4 2,1E4 > 6E5 9E4 2E3 0.8 2,9E2 > 1E4 5,1E3 8,7E3 3,1E4 2.5 1.0 1,8E2 > 1E4 2,5E3 3,9E3 2,5E4 100 1.2 116 > 1E4 1,4E3 1,3E3 2,0E3 > 6E5 2,7E4 1.4 80 > 1E4 7,2E2 1,1E3 1.6 60 > 1E4 4,6E2 4,2E2 6,8E2 1.8 44 > 1E4 3,0E2 2,8E2 1,2E4 2.0 35 > 1E4 2,1E2 1,9E2 3,2E2 2.2 28 > 1E4 1,5E2 136 8,4E3 2.4 22 > 1E4 108 99 1,6E2 > 6E5 2.7 17 7E3 70 63 100 3.0 11 6E3 47 44 69 5,2E3 2E5 SF3 5.0 1E3 6.5 10 2,5E3 10 2E2 3,5E2

2. Determination of the stability of BOPOR against ionizing radiation

Two H ₃ O ⁺ loaded BOPOR samples were exposed to various doses of ionizing radiation using a ⁶⁰ Co source. The ion exchange capacity was determined as described above before and after the irradiation. Table 2. 0 Gy 5.9 × 10 ⁶ Gy 1 × 10 ⁶ Gy Sample 1 5.37 meq / g 5.34 meq / g 4.90 meq / g Sample 2 5.37 meq / g 5.32 meq / g 4.86 meq / g

3. Determination of the ion exchange capacity of BOPOR

The ion exchange capacity Q _tot (meq / g) was determined by means of a sodium hydroxide back-titration method. For this, a column with 1 ml bed volume was filled with BOPOR (particle size 80-125 μm). 5 ml of 10% HCl was passed through the column with BOPOR, followed by rinsing with water to pH = 7.0. To determine the capacity, a certain amount of sodium hydroxide solution (30 ml of 0.1 M NaOH solution) was passed through the column and then flushed with water to pH = 7.0. The NaOH excess was titrated with 0.1 M HCl.

After conducting three independent back titrations, the BOPOR resin had an ion exchange capacity of 5.4 ± 0.2 meq / g. Table 3. Ion Exchange Capacity Q _tot Experiment 1 5.37 meq / g Experiment 2 5.23 meq / g Experiment 3 5.62 meq / g

4. Determination of the separation performance of BOPOR

As an example of the separation performance, the separation of the divalent cation Ba ²⁺ from the trivalent cation Lu ³⁺ in hydrochloric acid was investigated. A mixture of Ba ²⁺ -and Lu ^{3 +} cations, wherein Ba ²⁺ was present in large excess (mass ratio Ba / Lu 2300), was applied to the column with BOPOR column and then eluted with HCl. Ba ²⁺ was completely eluted with ~ 30 mL of 0.5 M HCl without Lu ³⁺ traces found in the eluate. Increasing the HCl concentration to 0.6 M and 0.7 M also did not result in Lu ³⁺ elution. Only at a concentration higher than 1 M did Lu ^{3+ elute} in a volume of ~ 15 mL ( 1 ). This example shows that the difference in K _D values by a factor of 10 to 50 allows the selective separation of the triply charged cations from excess dually charged cations.

Furthermore, the very high K _D values of heavy, singly charged cations enable their effective separation over a very broad pH range from all other highly abundant cations.

5. Preparation of the BOPOR resin

The new cation exchangers BOPOR was ₂ [B ₁₂ H _12] · 4H ₂ O, and thionyl chloride, SOCl ₂ synthesized by a polymerization reaction between lithium-dodecahydro-closo-dodecaborate tetrahydrate, Li,. Thionyl chloride was purified in vacuo by repeated melt-freezing prior to the reaction of dissolved hydrolysis products, HCl and SO ₂ . 100 mL of purified SOCl _{2 was} added to a glass vessel cooled with liquid nitrogen containing 10 g of Li ₂ [B ₁₂ H ₁₂ ] .4H ₂ O crystals and frozen. The vessel was pumped off in the cooled state. The reaction started with gentle melting of the thionyl chloride and continued with a slow increase in temperature up to 75 ° C. The evolved by the chemical reaction between SOCl ₂ and water of crystallization gases were pumped out during the reaction using a diaphragm pump. The reaction was over when gas evolution ended. The polymerized crystals were separated from the reaction solution by filtration and rinsed first with dilute hydrochloric acid and then with water and then dried in a drying oven at 60 ° C. The following reaction mechanism has been proposed: SOCl ₂ + H ₂ O → SO ₂ + 2HCl Li ⁺ + HCl → LiCl + H ⁺ and H ⁺ + H ₂ O → H ₃ O ⁺ SOCl ₂ + H ₃ O ⁺ → HCl + SOCl ⁺ + H ₂ O [B ₁₂ H ₁₂ ] ^2- + SOCl ⁺ → [B ₁₂ H ₁₁ SO] ^- + HCl [B ₁₂ H ₁₁ SO] ^- + [B ₁₂ H ₁₂ ] ^2- → [B ₁₂ H ₁₁ -SO-B ₁₂ H ₁₁ ] ^4- + H ⁺ etc.

• a) Schwefel und Wasserstoff wurde mit einem CHNS-Analysator bestimmt; S – 14,56%, H – 6,18%.
• b) Schwefel und Chlor wurde mit einem Elektronenmikroskop bestimmt, S:Cl = 1,87.
• c) Chlor wurde zusätzlich bei der Fällung mit Ag⁺ in Form von AgCl bestimmt: Cl – 7,92%.

The composition was determined by the following methods:

• a) sulfur and hydrogen were determined with a CHNS analyzer; S - 14.56%, H - 6.18%.
• b) Sulfur and chlorine were determined by electron microscope, S: Cl = 1.87.
• c) Chlorine was additionally determined in the precipitation with Ag ⁺ in the form of AgCl: Cl - 7.92%.

In addition, an infrared spectrum was recorded, in which the lines of the B ₁₂ cage, BH, B-Cl, BS and SO bonds were assigned. The following composition was detected for BOPOR: (H ₃ O) _2n [B ₁₂ H ₁₀ -xy (SO) _{1 + x} Cly], 5nH ₂ O, where x = 0.716 and y = 0.844; O - 36.92%, B - 34.34%, S - 14.56%, Cl - 7.92%, H - 6.25%.

Claims (15)

Cation exchanger containing a borane polymer according to the following general formula (I) or (II): [B _h H _h-2-km X _{1 + k} Y _m ] _n ^2n- (I) or [CB _{h-1 h-2 H-km} X _{1 +} Y _{k m] n} ^{n- (II)} wherein X is selected from the group consisting of: O, S, SO, SO ₂ , S ₂ , S (O) S, S (O) S (O), POR, PR ₃ , POR ₃ where R = F, Cl , Br, I, H, C ₁ -C ₄ -alkyl, aryl, wherein the aryl having one or more substituents OH, OR, SO ₃ H, COH, CO ₂ H, Br, Cl, F, CN, NH ₂ , CF ₃ , NO ₂ , methyl, ethyl; Y is selected from the group consisting of: OH, F, Cl, Br, OR, SH, SR, SR ₂ , SCN, CO, COR, CO ₂ R, NH ₂ , NH ₃ , NR ₃ , where R = C ₁ C ₄ alkyl, aryl, wherein aryl having one or more substituents OH, OR, SO ₃ H, COH, CO ₂ H, Br, Cl, F, CN, NH ₂ , CF ₃ , NO ₂ , C ₁ C ₄ alkyl substituted; h = 10 or 12; k is a real number from 0 to 2; m is a real number from 0 to 10 when h = 12, and a real number from 0 to 8 when h = 10; n is a natural number of> 10 ⁹ . Cation exchanger according to claim 1, characterized in that the structural unit polyhedra of the borane polymer are closo-boranes. Cation exchanger according to claim 1 or 2, characterized in that h = 10. Cation exchanger according to claim 1 or 2, characterized in that h = 12. Cation exchanger according to one of claims 1 to 4, characterized in that the borane polymer has exchangeable cations as counterions. Cation exchanger according to one of claims 1 to 5, characterized in that the borane polymer additionally contains water molecules. Cation exchanger according to claim 5 or 6, characterized in that the borane polymer is the composition (H ₃ O) _2n [B ₁₂ H _8.44 (SO) _1.716 Cl _0.844 ] _n · 5nH ₂ O Has. Cation exchanger according to one of claims 1 to 7, characterized in that the selectivity for cations in the order M ²⁺ <M ³⁺ <M ⁴⁺ increases. Cation exchanger according to one of claims 1 to 8, characterized in that the selectivity for monovalent cations depends on the ionic radius and increases in the order Li ⁺ ≈ Na ⁺ <K ⁺ <Rb ⁺ <Cs ⁺ ≈ Tl ⁺ ≈ Ag ⁺ . Cation exchanger according to one of claims 1 to 9, characterized in that it is stable over a pH range of 0 to 14. Cation exchanger according to one of claims 1 to 10, characterized in that it is stable to ionizing radiation. Cation exchanger according to one of Claims 1 to 11, characterized in that the cation exchanger charged with H ₃ O ⁺ exhibits a color change upon loading with metal ions. Cation exchanger according to one of Claims 1 to 12, characterized in that it is present as a solid insoluble in water and organic solvents, in particular resin. Cation exchanger according to one of claims 1 to 13, characterized in that it is immobilized on a matrix. Cation exchanger according to claim 14, characterized in that the matrix comprises cellulose and / or dextran and / or silica gel and / or magnetic beads and / or plastic beads.

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