Separation of Zr in the rubble waste generated at the Fukushima Daiichi Nuclear Power Station

Separation method of Zr using trans uranium resin (TRU resin) and tetra valent actinide resin (TEVA resin) was developed for the analysis of ⁹³Zr contained in the rubble waste. Zr, Nb, and U were quantitatively extracted on the TRU resin from 3 M HNO₃ and striped with 0.01 M HF, in addition, some part of Mo, Hg, Bi, and Th were also included in the stripping solution. The stripping solution was evaporated to eliminate HNO₃ and the residue was dissolved in 0.1 M HF. Finally, Zr was separated from Nb and Mo with the TEVA resin.     

Solvent extraction of hafnium(IV)

^{175, 181}Hafnium(IV) was extracted by HDBP in 2-ethylhexanol from 1–10M solutions of HClO₄, HCl and HNO₃, and 1–8M H₂SO₄. As with low polar organic phase diluents, the acidity dependence of the distribution ratio of Hf, D, passes through a minimum for HClO₄, HCl, and H₂SO₄ whereas only an increase of D can be observed with increasing HNO₃ concentration. From the slope analysis the following complexes were found to be extracted (HDBP=HA): HfA₄ at <4M HClO₄ and <5M HCl, lg K_extr=9, HfX₄(HA)₄ (X=ClO ₄ ⁻ , Cl⁻ or NO ₃ ⁻ ) at >5M HClO₄, >7M HCl and 1–10M HNO₃, Hf(SO₄)A₂(HA)_3–4 at <3M H₂SO₄, and Hf(SO₄)₂ (HA)₄ at >6M H₂SO₄. Coextraction of sulphate with hafnium from H₂SO₄ solutions was evidenced in experiments with macro concentrations of Hf(IV) and³⁵SO ₄ ²⁻ . Part XX: Coll. Czech. Chem. Commun., 40 (1975) 3617.     

A chelating resin containing 1-(2-thiazolylazo)-2-naphthol as the functional group; synthesis and sorption behavior for trace metal ions

A new polystyrene-divinylbenzene resin containing 1-(2-thiazolylazo)-2-naphthol (TAN) functional group was synthesized and its sorption behavior for 19 metal ions including Zr(IV), Hf(IV) and U(VI) was investigated by batch and column experiments. The chelating resin showed a high sorption affinity for Zr(IV) and Hf(IV) at pH 2. Some parameters affecting the sorption of the metal ions are detailed. The breakthrough and overall capacities were measured under optimized conditions. The overall capacities of Zr(IV) and Hf(IV) that were higher than those of the other metal ions were 0.92 and 0.87 mmol/g, respectively. The elution order of metal ions at pH 4 was evaluated as: Zr(IV)>Hf(IV)>Th(IV)>V(V)>Nb(V)>Cu(II)>U(VI)>Ta(V)>Mo(VI)>Cr(III)>Sn(IV)>W(VI). Quantitative recovery of most metal ions except Zr(IV) was achieved using 2 M HNO₃. Desorption and recovery of Zr(IV) was successfully performed with 2 M HClO₄ and 2 M HCl.     

Selective uptake of plutonium (IV) on calcium alginate gel polymer and TBP microcapsule

The uptake behavior of Pu(IV) has been investigated by using calcium alginate gel polymer (CaALG) and TBP microcapsules (TBP-CaALG). The characterization of CaALG and TBP-CaALG was examined by SEM and IR, and the uptake properties and distribution of Pu(IV) ions were estimated by batch method. The uptake rate of Pu(IV) on CaALG and TBP-CaALG in the presence of 5 M HNO₃ was attained within 6 and 4 h, respectively, and K _d values for CaALG and TBP-CaALG after 7 h-shaking were 50.2 and 53.2 cm³/g, respectively. Relatively large K _d values (90.3–425 cm³/g) were obtained for fresh CaALG and TBP-CaALG in the presence of 0.5–2 M HNO₃. Thus CaALG and TBP-CaALG are effective for the separation of Pu(IV) in the presence of highly concentrated HNO₃.     

Darstellung und Eigenschaften von Tetra(n-butyl)ammonium-cis-trifluorophthalocyaninato(2–)zirconat(IV) und -hafnat(IV); Kristallstruktur von (nBu4N)cis[Hf(F)3pc2–]

Preparation and Properties of Tetra(n-butyl)ammonium cis -Trifluorophthalocyaninato(2–)zirconate(IV) and -hafnate(IV); Crystal Structure of (ⁿBu₄N) ^cis [Hf(F)₃pc^2–] cis-Dichlorophthalocyaninato(2–)metal(IV) of zirconium and hafnium reacts with excess tetra(n-butyl)-ammoniumfluoride trihydrate to yield tetra(n-butyl)-ammonium cis-trifluorophthalocyaninato(2–)metalate(IV), (ⁿBu₄N)^cis[M(F)₃pc^2–] (M = Zr, Hf). (ⁿBu₄N)^cis[Hf(F)₃pc^2–] crystallizes in the monoclinic space group P2₁/n (# 14) with cell parameters a = 13.517(1) Å, b = 13.856(1) Å, c = 23.384(2) Å, α = 92.67(1)°, Z = 4. The Hf atom is in a ”︁square base-trigonal cap”︁”︁ polyhedron, coordinating three fluorine atoms and four isoindole nitrogen atoms (N_iso). The Hf atom is sandwiched between the (N_iso)₄ and F₃ planes (d(Hf–Ct_N) = 1.218(3) Å; d(Hf–Ct_F) = 1.229(3) Å; Ct_N/F: centre of the (N_iso)₄, respectively F₃ plane). The average Hf–N_iso and Hf–F distances are 2.298 and 1.964 Å, respectively, the average F–Hf–F angle is 84.9°. The pc^2– ligand is concavely distorted. The optical spectra show the typical metal independent π-π* transitions of the pc^2– ligand at c. 14700 and 29000 cm^–1. In the FIR/MIR spectra vibrations of the MF₃ skeleton are detected at 545, 489, 274 cm^–1 (M = Zr) and 536, 484, 263 cm^–1 (M = Hf), respectively.     

Solvent extraction of Hf(IV) from mixed electrolyte solutions into di-2-ethylhexylphosphoric acid (HDEHP)

Extraction of hafnium(IV) from aqueous sulfuric and sulfuric-nitric acid solutions into di-2-ethylhexylphosphoric acid (HDEHP) in xylene has been investigated. The Hf(IV) species extracted from 5M sulfuric acid was found to be HfY₂(HY₂)₂ where Y and HY₂ represent the anions of monomeric HY and dimeric H₂Y₂ forms of HDEHP, respectively. In the presence of nitrate ion the species extracted are found to be Hf(NO₃)Y(HY₂)₂ and Hf(NO₃)₂)(HY₂)₂. But when the aqueous phase is 3.0M HNO₃+2.5M H₂SO₄ only one species, Hf(NO₃)₂(HY₂)₂ was extrated. No synergism was observed from 5M H₂SO₄ by HDEHP with the addition of thenoyltrifluoracetone (HTTA).     

Catenated polysulfur ligands: the pentasulfides of di-η5-cyclopentadienyl-zirconium(IV) and -hafnium(IV)

The thiols Cp₂M(SH)₂, where M = Ti and Zr, react to form the complexes Cp₂MS₅ when treated with mono- and di-sulfur transfer reagents. Treatment of Cp₂MCl₂ with Li₂S₂ and sulfur gave Cp₂MS₅, M = Ti, Zr and Hf, in better yield. The new Zr and Hf complexes have a six-membered MS₅ ring in a chair conformation similar to the previously observed for M = Ti. Variable temperature NMR studies show that the barriers to MS₅ ring inversion decrease in the order Ti > Hf > Zr.     

Extraction and thermodynamic behavior of U(VI) and Th(IV) from nitric acid solution with tri-isoamyl phosphate

The extraction behavior of U(VI) and Th(IV) with tri-isoamyl phosphate–kerosene (TiAP–KO) from nitric acid medium was investigated in detail using the batch extraction method as a function of aqueous-phase acidity, TiAP concentration and temperature, then the thermodynamic parameters associated with the extraction were derived by the second-law method. It could be noted that the distribution ratios of U(VI) or Th(IV) increased with increasing HNO₃ concentration until 6 or 5 M from 0.1 M. However, a good separation factor (D _U(VI)/D _Th(IV)) of 88.25 was achieved at 6 M HNO₃, and the stripping of U(VI) from TiAP–KO with deionized water or diluted nitric acid was easier than that of Th(IV). The probable extracted species were deduced by log D-log c plot at different temperatures as UO₂(NO₃)₂·(TiAP)_(1–2) and Th(NO₃)₄·(TiAP)_(2–3), respectively. Additionally, △H, △G and △S for the extraction of U(VI) and Th(IV) revealed that the extraction of U(VI) by TiAP was an exothermic process and was counteracted by entropy change, while the extraction of Th(IV) was an endothermic process and was driven by entropy change.     

Schiff base derivatives of titanium(IV) and zirconium(IV)

The reactions of a few bifunctional and tridentate Schiff bases with titanium-(IV) and zirconium(IV) isopropoxides in equimolar and bimolar ratios are described. The resulting compounds have been obtained in almost quantitative yields and are of the general formulae M(SB)_x(OPrⁱ)_4?2X (where M = Ti or Zr; SB- = anion of the Schiff base SBH₂ and x = 1 or 2). Their molecular weights have been determined ebullioscopically and IR spectra recorded.     

Extraction of Zr(IV) by TBP-DMSO and TBP-Py from aqueous solutions containing monobasic acids

The distribution ratios for the extraction of Zr(IV) by TBP and its binary mixtures with DMSO or Py in n-dodecane in the presence of HNO₃, and HClO₄ have been determined. Based on stoichiometric and slope analysis methods a possible mechanism for the extraction has been proposed.     

Zirconium(IV) complexes ofSchiff bases

Zirconium(IV)Schiff base derivatives have been synthesised by reacting zirconium isopropoxide with monofunctional bidentateSchiff bases in different stoichiometric ratios. The resulting derivatives of the type Zr(O-Isopr)₃(SB) and Zr(O-Isopr)₂(SB)₂, whereSB ^– is the anion of the correspondingSchiff baseSBH, have been isolated in almost quantitative yields. Their molecular weights have been determined ebullioscopically and their ir spectra recorded.

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Zirkonium(IV)-Komplexe von Schiff-Basen

Zusammenfassung Es wurden Zirkonium(IV)-Schiff-Basen-Derivate in verschiedenen stöchiometrischen Zusammensetzungen über die Reaktion von Zirkoniumisopropoxid mit monofunktionellen zweizähnigenSchiff-Basen synthetisiert. Die Komplexe vom Typ Zr(O-Isopr)₃(SB) und Zr(O-Isopr)₂(SB)₂ [SB ^– als Anion derSchiff-BaseSBH] wurden in fast quantitativer Ausbeute erhalten. Es werden Strukturen vorgeschlagen, die auf ebullioskopisch bestimmten Molekulargewichten und den IR-Spektren basieren.

     

Adsorption behavior of 181W and 93mMo as lighter homologues of seaborgium (Sg) in HF/HNO3 on anion-exchange resin

Adsorption of carrier-free radiotracers ¹⁸¹W and ^93mMo produced in the ¹⁸¹Ta(p, n) and ^natNb(p, n) reactions, respectively, on anion-exchange resin was studied in mixed solution of HF and HNO₃ in a concentration range of 10⁻⁴–10⁻¹ M HF/0.1 M HNO₃. Distribution coefficients (K _d) of ¹⁸¹W and ^93mMo at 70 °C showed the V-shaped variation with the minimum at around 10⁻¹ M HF/0.1 M HNO₃, although variation of the K _d values for ^93mMo was quite small compared with that for ¹⁸¹W. Formation of oxofluoro complexes for W and Mo is briefly discussed.     

Extraction of some elements of the groups IV b and VI b with 1-phenyl-3-methyl-4-caproyl-pyrazolone-5 (PMCP) from aqueous mineral acid solutions

Solvent extraction of Cr(VI), Mo(VI), W(VI) and Hf(IV) with 1-phenyl-3-methyl-4-caproyl-pyrazolone-5 (PMCP) in methyl isobutylketone (MIBK), xylene and chloroform (CHCl₃) from mineral acid solutions was studied. Chromium(VI) is not extracted from any of the acids studied (HCl, H₂SO₄ and HClO₄). Molybdenum(VI) is quantitatively extracted by the reagent in xylene and CHCl₃ from HClO₄ and HNO₃ solutions. It is also extracted quantitatively by the reagent in MIBK from HCl, HNO₃ and H₂SO₄ solutions but the participation of the diluent as extractant is considerable. Tungsten(VI) is quantitatively extracted in xylene from 9M HClO₄ solution. MIBK used as diluent also affects its extraction with PMCP. Hafnium(IV) is not extracted from H₂SO₄ solutions while it extracts more than 99% at 3M HNO₃ and above. The extracted species likely are: MoO₂(PMCP)₂, WO₂(PMCP)₂ and Hf(PMCP)₄, respectively.     

Solvent extraction of hafnium(IV) by TBP and topo from acidic organic-aqueous solutions

Tracer concentrations of Hf(IV) were extracted by 60% TBP solution in benzene from 5M HClO₄, 5M HCl, 6M HNO₃ and 8M H₂SO₄ solutions, and by 1·10^?4 M TOPO solution in benzene from 2M HClO₄ and 2M HCl solutions in the presence of a variety of organic solvents miscible with the aqueous phase. Whereas for TBP these solvents caused an increase of HF(IV) extraction, an opposite effect was observed for TOPO. The results were discussed from the point of view of various solute-solvent and solvent-solvent interactions.     

LIX 84 as an extractant for throium(IV), uranium(VI) and molybdenum(VI)

The extraction order of Th(IV), U(VI) and Mo(VI) based on pH_0.5 values is Mo(VI)>U(VI)>Th(IV). Quantitative extraction has been observed for U(VI) by mixture of 10% (v/v) LIX 84 and 0.1M dibenzoylmethane at pH 4.2 and by mixture of 10% LIX 84 and 0.05M HTTA in the pH range 5.5–7.3 and for Mo(VI) by 10% LIX 84 from chloride media at pH 1.5. The order of extraction of Mo(VI) from 1N acid solutions is HCl>H₂SO₄>HNO₃>HClO₄ and extraction decreases very rapidly with increase in the concentration of HCl as compared to that from H₂SO₄, HNO₃ and HClO₄ acid solutions. The diluents C₆H₆, CCl₄ and CHCl₂ are found to be superior ton-butyl alcohol and isoamyl alcohol for extraction of Mo(VI). Influence of concentration of different anions on the extraction of U(VI) and Mo(VI) has been studied. Very little extraction has been observed in case of Th(IV) by LIX 84 or its mixtures with other chelating extractants or neutral donors.     

Preconcentration of uranium(VI) and thorium(IV) from aqueous solutions using low-cost abundantly available sorbent

Olive cake as low-cost abundantly available sorbent has been characterized by N₂ at 77 K adsorption, porosity analysis, elemental analysis and IR spectra and has been used for preconcentrating of uranium(VI) and thorium(IV) ions prior to their determination spectrophotometrically. The optimum pH values for quantitative sorption of U(VI) and Th(IV) are 4–7 and 3–7, respectively. The enrichment factor for the preconcentration of U(VI) and Th(IV) were found to be 125 and 75 in the given order. The sorption capacity of olive cake is in the range of 2,260–15,000 μg g⁻¹ for Th(IV) and in the range of 1,090–17,000 μg g⁻¹ for U(VI) at pH 3–7. The sorbent exhibits good reusability and the uptake and stripping of the studied ions were fairly rapid. The elution of U(VI) and Th(IV) was performed with 0.3–1 M HCl/1–2 M HNO₃ and 0.3–0.8 M HCl/1 M HNO₃, respectively. The precision of the method was 1.8 RSD% for U(VI) and 2.5 RSD% for Th(IV) in a concentration of 1.00 μg mL⁻¹ for 10 replicate analysis. The influence of some electrolytes and cations as interferents was discussed. Separation of U(VI) and Th(IV) from other metal ions in synthetic solution was achieved.     

Two-phase reactions of tin(IV)–tetraphenylporphine complexes as carrier of anion selective electrodes

Two-phase reactions of [Sn(OH)₂(tpp)] with lipophilic anions and inorganic acids were studied and compared with those of [Zr(OH)₂(tpp)] having the same oxidation state of the central metal ion but different structural characteristics. The reaction with tetrakis[3,5-bis(trifluoromethyl)phenyl]borate formed a 2:1 cationic dimer and 1:1 and 1:2 ion-pairs, while the reaction with dodecyl sulfate formed 1:1 and 1:2 ion-pairs. The 1:1 and 1:2 species formed concomitantly in the reaction with HCl and CH₃COOH having higher coordination abilities, while forming in stepwise manner in the reaction with HClO₄ and HNO₃ having lower coordination abilities. The 2:1 cationic dimer of Sn(IV) had significantly lower stability than that of Zr(IV). The affinity of Sn(IV) for Cl⁻ relative to OH⁻ was much higher, compared with Zr(IV). Except in extremely acidic media, [SnCl₂(tpp)] working as a carrier in PVC membranes hydrolyzed to give [Sn(OH)Cl(tpp)] or [Sn(OH)₂(tpp)], which showed stronger but less-selective potential responses at lower pH and weaker but more-selective responses to salicylate at higher pH. The affinities and responses of Sn(IV) complexes to oxygen-containing anions were weaker than those of Zr(IV) complexes.     

Extraction of molybdenum(VI) by 4-(5-nonyl)pyridine in benzene from aqueous mineral acid solutions containing thiocyanate ions

Extraction of Mo(VI) by 4-(5-nonyl)pyridine (NPy) in benzene from mineral acid solutions containing thiocyanate ions has been investigated at room temperature (23±2°C). From mineral acid (HCl, HNO₃, and H₂SO₄) solutions alone Mo(VI) is not extracted quantitatively while the presence of small amounts of KSCN in the system augments the extraction by a large factor. Stoichiometric studies indicate that ion-pair type complexes (NPyH)₂·[MoO₂(SCN)₄] are responsible for the extraction. Separation factors determined at fixed extraction conditions (0.1M Npy/C₆H₆–0.1M acid +0.2M KSCN) reveal that Ag(I), Cu(II), Co(II), Zn(II), Hg(II) and U(VI) are co-extracted while a clean separation from alkali metals, alkaline earths and some transition metals like Ln(III), Zr(IV), Hf(IV), Cr(III), Cr(VI) and Ir(III) is possible. Some of the complexing anions like oxalate, citrate, acetate, thiosulfate or ascorbate do not affect the degree of extraction of Mo(VI) allowing it to be recovered from diverse matrices.     

Synthesis of N,N’-dimethyl-3-oxa-glutamic acid and application in the simplification of TRPO process

To simplify TRPO process, a novel ligand, N,N’-dimethyl-3-oxa-glutaramic acid (DMOGA), was synthesized and used for stripping of An(III, IV) from 30% TRPO-kerosene. The distribution ratios for transuranium elements, including Np(IV), Pu(IV), Am(III), and some fission products, including Eu(III), Fe and Zr between 30% TRPO-kerosene and various HNO₃-DMOGA solutions were measured. An(III, IV) and Ln(III) extracted to TRPO from simulated high level liquid waste could be recovered with an efficiency of 99.9% above in one stream with a 3-stage crosscurrent strip experiment with 0.2M DMOGA in HNO₃ solution. Using this new agent, the back extraction of TRU elements from loaded TRPO phase becomes more simple and practical. Therefore, the original TRPO process could be simplified.     

Extraction and separation of Th(IV) and U(VI) from nitric acid media using PIA-8 and HDEHP

Extraction behavior of Th(IV) and U(VI) has been investigated with bis(2-ethylhexyl) phosphinic acid (PIA-8) and bis(2-ethylhexyl) phosphoric acid (HDEHP) from nitric acid media in toluene. The optimum conditions for extraction of these metals have been established by studying various parameters like acid concentration, pH, reagent concentration, diluents and shaking time. The extraction of Th(IV) was found to be quantitative with 0.3-2.5M HNO₃ by 2.5^.10^-2M HDEHP and in the pH range 0.1-2.5 with 2.3^.10^-2M PIA-8 in toluene. U(VI) was completely extracted in the acidic range of 0.1-2.0M HNO₃ with 2.2^.10^-2M HDEHP and in the pH range of 1.0-3.0 with 2.0^.10^-2M PIA-8 in toluene. The probable extracted species have been ascertained by log D-log c plot as UO₂ R₂ ^.2HR with both the reagents and Th (NO₃)₂R₂ ^.2HR with PIA-8 and Th (NO₃)₃R^.3HR with HDEHP, respectively. Temperature dependence of the extraction equilibrium is examined by the temperature variation method. Separation of U(VI) and Th(IV) was also carried out from commonly associated metals.