Ceric tungstate as sorbent for polyvalent tracer cations and as an ion exchanger for separation of carrier-free95Nb from95Zr and113mIn from113Sn

The uptake of a few polyvalent ions Ca²⁺ Cu²⁺, Zn²⁺, Cd²⁺, UO²⁺, Cr³⁺, Y³⁺, Ce³⁺, Nd³⁺, Sm³⁺, Tb³⁺, Tm³⁺, Yb³⁺, Lu³⁺, Zr⁴⁺, Hf⁴⁺, Sn⁴⁺, Nb⁵⁺, Se⁶⁺, Mo⁶⁺ and W⁶⁺ at very small concentrations has been studied over ceric tungstate exchanger. A good column variety of the material was prepared by mixing ceric sulphate in 2N H₂SO₄ and aqueous solution of sodium tungstate in suitable proportion. The ratio of cerium: tungstate was obtained to be 11. Separation of carrier-free⁹⁵Nb from⁹⁵Zr and^113mIn from¹¹³Sn have been carried out by applying a very simple chemical procedure over the column of ceric tungstate. The -spectrum of separated⁹⁵Nb and^113mIn products were found to be of high radionuclidic purity. The separation procedure took less than 15 min and the yields were close to 100%.     

Adsorption of several tracer cations and separation of234Th from238U and113mIn from113Sn on tin dioxide

The uptake of 22 cations at tracer concentrations has been studied over hydrous tin dioxide exchanger material. A granular variety of tin dioxide was prepared from the reaction of tin(IV) chloride with NaOH solution, and the formula of the material was ascertained to be SnO₂·1.7 H₂O. Radiochemical separation of carrier-free²³⁴Th from²³⁸U and^113mIn from¹¹³Sn was achieved over a tin dioxide column. The separated products were of high radionuclidic purity. The overall separation procedures are very simple and quick with quantitative yield.     

Radioactive nuclides in the marine environment--distribution and behaviour of 95Zr, 95Nb originated from fallout

To investigate behaviour of 95Zr, 95Nb in the marine environment, various samples have been collected and measured by means of Ge(Li) gamma-ray spectrometry and/or radiochemical analysis during a period from 1974 to 1982 at coastal area of Tokai-mura, Ibaraki prefecture. Concentration of the nuclides in seaweeds increased remarkably after atmospheric nuclear detonation by P.R. of China, and the activity ratio between the nuclides changed by time was not fit well by the transient decay equation. Concentration variation in sea water was smaller than that in sea weeds, and the minimum change in sea sediment. Increase of concentration in these environmental samples was observed in chronological order of sea water, sea weeds then sediment after detonations, suggesting that the uptake of the nuclides by these sea weeds from sea water is faster than that via root. Observed concentration factors on the nuclides by sea weeds were calculated from the observed concentrations in sea water and sea weeds. Maximum values on 95Zr and 95Nb were 2110, 2150, respectively for Ecklonia cava and Eisenia bicyclis.     

Separation of95Zr and95Nb by means of sorption on silica gel from hydrochloric acid solutions

The adsorption behaviour of zirconium and niobium on silica gel from hydrochloric acid solutions was studied by batch equilibrations and passage through columns. On the basis of this, new methods are suggested for the separation and purification of⁹⁵Zr and⁹⁵Nb in hydrochloric acid and hydrochloric acid—methanol solutions. The methods are comparatively simple and rapid, and both zirconium and niobium can be obtained in a radiochemically pure state.     

Ceric phosphate as ion exchanger in the separation of carrier-free210Bi from210Pb,90Y from90Sr and UX1 from u

Separations of tracer cations in parent daughter systems such as carrier-free²¹⁰Bi from²¹⁰Pb,⁹⁰Y from⁹⁰Sr and UX₁ from U have been carried out in a column of ceric phosphate as ion exchanger. The exchanger has been prepared by mixing ceric sulfate in hot 10M orthophosphoric acid at 80°C and keeping for overnight. A pale yellow coloured precipitate was formed which was washed, dried at 70°C for 48 hours when a hard, granular variety suitable for column use, with a cerium to phosphate ratio of 1∶2 was obtained. 0.1M H₃PO₄ was used as medium in each of the systems studied. The β-decay curves of the separated²¹⁰Bi and⁹⁰Y and the γ-spectrum of UX₁ show that all these activities are radiochemically pure. The separation procedures adopted in each case were very clean and simple, gave quantitative yields and took less than half an hour.     

Separation of95Zr and95Nb from each other and from other fission products by adsorption and desorption on silica gel using hydrochloric acid solutions

The silica gel adsorption behaviour of zirconium, niobium, ruthenium and cerium in hydrochloric acid has been investigated by batch and column techniques. A satisfactory radiochemical separation of zirconium and niobium from each other and from other fission products has been achieved by a two column technique. The recommended procedure consists of sorption of all the nuclides on a primary silica gel column. Fifteen per cent of⁹⁵Nb, all of the zirconium and all of the other fission products are eluted first by washing with 5.5 M HCl. A second elution with concentrated hydrochloric acid then recovers the⁹⁵Nb (free from other products). The solution from the first elution after evaporation to 1 ml is then passed through another silica gel column and successively washed with 0.5M HCl, 5.5M HCl and concentrated HCl to obtain three fractions—other fission products—⁹⁵Zr free from other products—⁹⁵Nb free from other products, respectively.     

The adsorption behaviour of99Mo(VI),238U(VI),95Zr(IV) and95Nb(V) on alumina

The distribution of Mo(VI) and the interfering radiocontaminants U(VI), Zr(IV) and Nb(V) have been investigated between chromatographic alumina and aqueous hydrochloric acid solutions of concentrations ranging from 0.5M to 11M. At low acidities (less than 1M HCl) the distribution coefficients increase with the decrease of acid concentration, while in the region of 2–4M they increase with the increase of the acid concentration. Above 4M HCl, the increase inK _D continues with the acid concentration for both Zr(IV) and Nb(V), but constant values are reached for U(VI) and Mo(VI).     

Adsorption of Zr,Hf, Nb,Ta and Pa on macroporous anion exchangers in HF medium

The behaviour of the elements Zr, Hf, Nb, Ta and Pa has been investigated on macroporous anion exchange resin BIORAD AGMP 1 in HF medium (from 0.02 to 2M). All the studied elements show strong adsorption properties at low HF concentration. The adsorption was found to be highly dependent on H⁺ and F^– concentrations. The distribution of possible adsorbable complexes is discussed.     

Role of stannic phosphate in the uptake of cations. Separation of zirconium from thorium and cadmium from indium at tracer concentrations

The uptake of Na⁺, K⁺, Rb⁺, Cs⁺, Ag⁺, Ca²⁺, Cu²⁺, Sr²⁺, Cd²⁺, Ba²⁺, Pb²⁺, Sc³⁺, Co³⁺, Y³⁺, Sb³⁺, Tb³⁺, Zr⁴⁺ and Th⁴⁺ cations at very small concentrations has been studied over a column of stannic phosphate. The exchanger was prepared by mixing H₃PO₄, NaCl and SnCl₄ in suitable proportions and the ratio of PSn, in the product was obtained to be 1.96. Radiochemical separations of carrier free⁹⁵Zr from²³⁴Th and^115mIn, from¹¹⁵Cd have been carried out by adopting a simple chemical procedure over a column of stannic phosphate. The -spectrum analysis showed that the separated products are of high radionuclidic purity. The separation procedures took less than half an hour with quantitative yield.     

Extraction and separation of Zr,Nb and Hf by Aliquat 336 and its mixtures with TOPO from acidic thiocyanate media

Presence of thiocyanate ions results in appreciable extraction of Zr(IV) by Aliquat 336 from low aqueous HCl acidities, i.e., 0.1 to 4.5M. The variation of concentrations of HCl, thiocyanate and Aliquat 336 greatly influences the extent of extraction. Mixtures of Aliquat 336 and TOPO result in synergistic extraction of Zr and Hf from acidic thiocyanate media, the extracted species being the disolvate with TOPO. By controlled adjustment of HCl, SCN^– and Aliquat 336 concentrations, separation of Zr, Nb and Hf is possible. A maximum separation factor (D_Nb/D_Zr) of 3675 has been achieved under certain conditions.     

Separation of carrier-free210Bi and UX1 from210Pb and U,respectively, using silica gel as ion exchanger

Radiochemical separations of carrier-free²¹⁰Bi and UX₁ activities from²¹⁰Pb and U, respectively, have been carried out using a silica gel column.²¹⁰Pb was adsorbed in the column as molybdate and²¹⁰Bi passed unadsorbed. Lead activity was next removed with 25 ml of 0.1 M HNO₃. In the case of separation of UX₁, the coloured carbonate complex of U was removed from the silica surface by washing with saturated sodium carbonate solution, keeping UX₁ retained, and finally UX₁ was washed out with 25 ml of conc. HNO₃. Studies of the beta decay of²¹⁰Bi and the γ-spectrum analysis of UX₁ has shown that the separated products in both cases are of high radiochemical purity. The processes in each case took less than one hour and the yield was satisfactory.     

Structural studies on the hydrolysis products of Ti,Nb and Zr alkoxides

Raman scattering was used to identify the vibrational modes of amorphous hydrolysis products of metal alkoxides and the corresponding sintered materials. These results were combined with X-ray diffraction data to identify the various isopoly complex groups which occurred in such materials.     

Sorption of Hf, Zr and Nb on organic and inorganic ion-exchangers from mineral acids solutions

Sorption coefficients of Hf, Zr and Nb on nickel-potassium hexacyanoferrate(II) (NF), nickel hexacyanoferrate(II) composite ion exchanger (NCF) and on the ion exchange resins (Dowex-1 and Dowex-50) from inorganic acids solutions were determined. The results obtained indicate that hafnium, zirconium and niobium in dilute sulphuric and hydrochloric acids form anionic and cationic complexes which sorbed on the ion exchangers studied.     

Quantification of Nb and Zr in the irradiated pressure tubes from Wolsong CANDU Unit 1 by neutron activation analysis

When the Wolsong 1st CANDU reactor in Korea is reaching the end of its original lifespan, decommissioning has been one of the largest issues faced by the nuclear industry and the government for the estimation of expense. The radioactive sources in the construction stuffs and components of the reactor such as pressure tubes, steam generators must be evaluated for the estimation of the appropriate expense for the decommissioning. Unfortunately we do not have exact information about the initial composition of the pressure tubes. In this study the elemental contents of Nb and Zr in the activated zircaloy pressure tubes was investigated. Nb is one of the important elements that characterize the physical and mechanical properties of the pressure tube and a major source of high radioactivity. The prepared samples were strongly irradiated again in the vertical irradiation channel at the HANARO research reactor in the Korea Atomic Energy Research Institute (KAERI) and then measured by an HPGe detector.     

Gas chromatographic separation of isomeric aminophenols,aniline, phenol,benzoquinone and azobenzene on an HP-1 capillary column

A gas Chromatographic method for the determination of isomeric aminophenols, aniline, phenol, azobenzene andp-benzoquinone has been developed. The non-polar HP-1 capillary column has been found to be more suitable for their separation than a polar Carbowax-20M packed column. The detection limits of the compounds lie between 0.15 and 3.3 ng/l. This method has been applied for the determination of oxidation products of aniline in different reactions. It also furnishes a rapid method for the separation and quantitation of mixtures of aniline, phenol and their derivative isomeric aminophenols with linear calibrations up to at least 0.75 mM, with coefficients of variation of about 6%.     

Adsorption behavior of Zr, Hf, Nb, Ta and Pa on macroporous anion exchanger in NH4SCN/HClO4 and NH4SCN/HF media

The possible use of thiocyanate and ammonium thiocyanate-hydrofluoric acid mixtures for quantitative anion exchange separation of zirconium from hafnium and niobium from tantalum and protactinium has been investigated. Distribution coefficients of zirconium(IV), hafnium(IV), niobium(V), tantalum(V) and protactinium(V) on macroporous BIO-RAD AGMP1 resin over a wide range of SCN and SCN/HF concentrations have been determined. The simultaneous presence of these two complexing agents causes a strong decrease of the adsorption phenomena.     

Combined cation-exchange and extraction chromatography for the concomitant separation of Zr, Hf, Th, and the Lanthanides from geological materials

A new method was developed, aiming to overcome the iron and titanium interferences which severely limit the applications of a recently introduced extraction chromatography material, referred to as RE resin (formerly, RE Spec), to the analysis of geological samples. The separation scheme is based on the combined use, in tandem columns, of the conventional AG50WX4 cation-exchange resin and the RE extraction chromatography material, without any intervening evaporation step. The Lanthanides are recovered quantitatively, while recoveries for Zr, Hf and Th range from 94 to 98%. These three elements are determined using the isotope dilution method, thereby alleviating the need for a yield correction. Compared with conventional methods based on cation-exchange, this combined scheme offers a greater multi-element capability, significant miniaturisation, acid wastes reduction, and a higher degree of purity of the separated analytes with regard to unwanted elements such as Ba and residual Ca and Al. This concomitant isolation of 17 trace elements of great interest in the Earth and Environmental Sciences, achieved with excellent recoveries and satisfactory blank levels, can be used prior to high precision analysis of ultra-trace elements in geological samples by ICP-Mass Spectrometry.