Deposition of Nickel and Cobalt Ions on Heated Surface under Nucleate Boiling Condition

The depositionof Ni and Co ions on a heated surface of simulating fuel rods has been studied in water at atmospheric and 70 atm pressures during nucleate boiling.

The effects of various factors, including heat flux of the heated surface, concentration of coexisting iron oxide (αFe₂O₃ and concentration of Ni and Co ions, on their deposition rate have been investigated. The model for iron oxide deposition which is based on microlayer evaporation and drying out phenomena in the nucleate boiling bubble was shown to be applicable to the deposition of Ni and Co ions. That is, dW/dt=K.Q.C/L, where dW/dt is the deposition rate, K the deposition rate coefficient, Q the heat flux, C the ion concentration, and L the latent heat of vaporization. The K value of Ni ion is about 0.1 and independent of iron oxide concentration. On the hand, the K value of Co ion increases with iron oxide concentration and seems to approach that of iron oxide concentration and seems to approach that of iron oxide (0.3). The Co ion deposited with iron oxide forms Co ferrite. Solubility of Co ferrite is small compared with that of Co deposits without iron oxide (CoO or Co(OH)₂). The increase in the K value of Co ion with iron oxide concentration is attributed to the change in chemical form of Co deposits into more stable species not favoring Co release.     

The characteristics and mechanism of Co(II) removal from aqueous solution by a novel xanthate-modified magnetic chitosan

A novel xanthate-modified magnetic chitosan (XMCS) was prepared, characterized and applied for Co(II) removal from aqueous solution, and compared with magnetic chitosan (MCS). The characteristics and mechanism of Co(II) sorption was investigated. The experimental results showed that the introduction of thiol group on magnetic chitosan greatly increased the adsorption capacity for Co(II). The kinetics of Co(II) sorption could be described by pseudo second-order equation, and the adsorption isotherm followed the Langmuir model for both MCS and XMCS. The maximum adsorption capacity was found to be 18.5 mg/g and 2.98 mg/g, respectively from the Langmuir isotherm for XMCS and MCS. The mechanism of Co(II) adsorption onto XMCS was tentatively proposed through FTIR and XPS analysis.     

Study of Multi-loaded Metal Salt-Ion Exchange Resins, (I) Multi-loaded Nickel Ferrocyanide-Anion Exchange Resin and Nickel Ferrocyanide · calcium Phosphate-Anion Exchange Resin

This report discusses the preparation of a number of metal salt-ion exchange resins and their application to radiochemical separation.

The resins prepared by the subject method have properties of both metal salt and ion exchange resin.

The present report describes the preparation and application of multi-loaded metal salt-ion exchange resin which contain one or more kinds of insoluble metal salt in an ion exchange resin, for which the residual ion exchange ability of an intermediate metal salt-ion exchange resin is utilized.

The properties of multi-loaded nickel ferrocyanide-anion exchange resin and nickel ferrocyanide-calcium phosphate-anion exchange resin are also discussed.     

Radiochemical Application of “Iron Ferrocyanide-Anion Exchange Resin”

Preparation of iron ferrocyanide-anion exchange resin and adsorption of ¹³⁷Cs on the resin are described.

The resin was found to effectively adsorb ¹³⁷Cs from concentrated nitric acid solution, contrast to the negative results previously obtained with copper ferrocyanide-anion exchange resin.

A discussion is given of the possibility of applying the iron resin to the removal of ¹³⁷Cs from fuel reprocessing waste solution.

Fission products were effectively separated from each other with a column of this resin, utilizing the properties possessed by it of both iron ferrocyanide and the parent ion exchange resin.     

Separation of strontium from low level radioactive waste solutions using hydrous manganese dioxide composite materials

⁹⁰Sr is one of the major isotopes present in the low level radioactive liquid waste (LLW) generated during operation of nuclear reactors and spent fuel reprocessing plants. A composite ion exchange material consisting of hydrous manganese oxide and poly methyl methacrylate (PMMA) was developed for removal of strontium from aqueous radioactive waste. The prepared composite material showed very good strontium adsorption properties in aqueous solutions. Sorption of strontium on the composite material as a function of pH, equilibration time and strontium ion concentrations were studied. The process of sorption of strontium from solution was analysed using different isotherm models like Langmuir, D-R and Freundlich. Four different error functions were employed to find out the most suitable isotherm model to represent the experimental data and it was found that Freundlich model best fits the sorption of strontium on the composite material. Analysis of the data obtained from the sorption kinetics studies showed that the data fitted better to the pseudo-second order kinetic model. Lab scale column performance study of the composite material revealed that the material could be effectively used in column operations to remove strontium from LLW solutions.     

磁性MOFs材料Fe3O4@SiO2@UiO-66-SO3H对Co(Ⅱ)的吸附性能

通过水热法制备了磁性MOFs材料Fe₃O₄@SiO₂@UiO-66-SO₃H,并利用红外光谱仪（FT-IR）、X射线衍射仪（XRD）、比表面积测试（BET）、振动样品磁强计（VSM）、X射线光电子能谱仪（XPS）等对材料结构、形貌和性能进行表征。考察了溶液pH值、时间、温度、Co(Ⅱ)初始浓度对Fe₃O₄@SiO₂@UiO-66-SO₃H吸附性能的影响。结果表明,在pH=8.3、温度为298 K下,Fe₃O₄@SiO₂@UiO-66-SO₃H对Co(Ⅱ)的理论最大吸附量为106 mg/g;吸附过程符合准二级动力学模型和Langmuir等温模型,吸附是一个自发的吸热过程。Fe₃O₄@SiO₂@UiO-66-SO₃H在外加磁场下易从水溶液中分离,5次循环后仍具有较强的吸附性能。     

Ion Exchange Separation for Decontamination of Centrifuge Enrichment Plant

Ion exchange separation of uranyl ion (UO²⁺ ₂) from metal cations has been carried out by the columnar operation using ion exchange resins in 0.1 mol/dm³ sulfuric acid medium. Uranyl ion was adsorbed in an anion exchange resin and the rest metal cations, Fe(III), Al(III), Cr(III), Ni(II) and Cu(II) ions, were adsorbed in a cation exchange resin in this system. Desorption of uranyl ion and metal cations adsorbed in the resins were tested by 2 mol/dm³ sulfuric acid solution. Desorbed elements were confirmed to be precipitated by appropriate alkaline solutions. On the basis of the results obtained, a concept was made on a decontamination system for uranium-contaminated waste solution from centrifuge enrichment plant.     

Effect of Metallic Impurities on Oxidation Reaction of Ion Exchange Resin, (II)

The catalytic effect of six metallic impurities on the oxidation reaction of cation exchange resin was investigated. The impurities, which were originally adsorbed onto the resin by an ion exchange method, combined with S present in the functional sulfonic acid group during heat-treatment in a nitrogen atmosphere to give the metal sulfides. The sulfides were subsequently oxidized to metal oxides.

In the case of Pd²⁺, Cu²⁺, Fe²⁺ and Fe³⁺ impurities, their sulfides were easily converted into oxides, which catalyzed the resin oxidation. Their catalytic activities depended on the heat of formation of the catalyst oxides ΔH‘₀; the lower was ΔH’₀, the more active the catalyst was. However, Co²⁺ and Ni²⁺ impurities had relatively low catalytic activities. This was because Co and Ni sulfides slowly changed into oxides, and the main chemical compositions of the impurities were not oxides but sulfides, which had no catalytic effect on the resin oxidation.     

磁性富羧基碳复合材料的制备及对Pb(Ⅱ)、Ni(Ⅱ)、Hg(Ⅱ)和U(Ⅵ)的吸附

采用溶剂热法制备了富羧基碳,随后通过化学共沉淀法合成了磁性富羧基碳复合材料。利用透射电子显微镜(TEM)、红外光谱分析(FTIR)、X射线衍射(XRD)、振动样品磁强计(VSM)、热重差热分析(TGA)、zeta电位分析及比表面积(BET)等手段对磁性富羧基碳的形貌、组成、结构、磁性以及表面电荷特性等进行了表征,并考察了富羧基碳和磁性富羧基碳对Pb(Ⅱ)、Ni(Ⅱ)、Hg(Ⅱ)和U(Ⅵ)的吸附性能。结果表明:富羧基碳经磁性改性后表面负载了铁氧化物纳米颗粒,比表面积由29.2m2/g提高到45.4m2/g,热稳定性提高,由磁滞回线可知,磁性富羧基碳的饱和磁化强度为30.68A.m2/kg。Pb(Ⅱ)、Ni(Ⅱ)、Hg(Ⅱ)和U(Ⅵ)在磁性富羧基碳上的平衡吸附容量分别为477.50、23.50、260.20、54.86mg/g,低于富羧基碳,吸附等温线符合Langmuir等温模型。从磁性富羧基碳对Pb(Ⅱ)、Ni(Ⅱ)、Hg(Ⅱ)和U(Ⅵ)均具有较高的吸附容量和不同吸附剂对U(Ⅵ)吸附容量的比较可以看出,该吸附剂是重金属污水和放射性废液处理领域中极具发展前景的吸附材料。     

磁化TEVA树脂的制备及其表征

磁助制样可有效降低X射线荧光光谱（XRF）方法的检出限,该制样方法的核心是制备磁性分离材料。本工作使用共沉淀磁化的方法制备磁化TEVA树脂作为磁性分离材料。该材料可用于磁助制样/XRF分析后处理样品中的微量锝。通过扫描电镜、X射线衍射（XRD）、红外等分析手段对磁化TEVA树脂进行表征,结果显示磁化树脂中铁氧化物以物理镶嵌的方式与TEVA树脂相结合,其主要成分为纳米四氧化三铁。制得的磁化TEVA树脂既保留了TEVA树脂在低酸下对TcO₄^-选择性吸附的性能,又具有顺磁性,可用于磁助制样/XRF分析方法。该制备方法重复性好,制得的磁化树脂性能稳定、良好,用于磁助制样时制样回收率大于99%,可有效降低方法的检出限。     

Decontamination of Radioactive Contaminants from Iron Pipes using Reactive Microemulsion of Organic Acid in Supercritical Carbon Dioxide

The ferrite fixed on the iron pipes was decontaminated by a reactive microemulsion in supercritical carbon dioxide (SC-CO₂). The specimens were prepared by treating the iron pipes with steam at 1,273 K for 2 min. The specimen was not dissolved in 3 mol·dm^?3 HNO₃ because its surface was covered with ferrite, while the original iron pipe was easily dissolved. This difference was used for determination of the fraction of ferrite. The fraction of ferrite covering the iron pipes was 1.5±0.3 wt%. A microemulsion containing organic acid was prepared using a fluorinated reagent, pentade-cafluorooctanoic acid (PFOA), and a non-fluorinated surfactant, polyoxyethylene (2) nonylphenyl ether (NP-2) and citric acid. In the former system, PFOA acted as a surfactant as well as an acid. By observation of the phase equilibrium, the microemulsion was found to be stabilized when the molecular ratio of water to surfactant, the w value, was 5.0 for the PFOA+H₂O+SC-CO₂ system, and 8.7 for the NP-2+citric acid+SC-CO₂ system at 25 MPa, and 323 or 353 K. Although the removal fractions of the ferrite were 0 and 1% for the PFOA and NP-2 system, respectively, at 25 MPa, 323 K, they increased to 92 and 56% at 25 MPa, 353 K.     

Equilibrium and kinetic studies of selective adsorption and separation for strontium using DtBuCH18C6 loaded resin

A crown ether loaded resin was prepared by successive impregnation and fixing the 4′,4′(5″)-di(tert-butylcyclohexano)-18-crown-6 (DtBuCH18C6) and its molecule modifier, 1-dodecanol, onto the porous silica/polymer composite support (SiO₂-P particles). The characterization of DtBuCH18C6 loaded resin was examined by thermal gravimetry and differential thermal analysis and electron probe microanalysis. The adsorption behavior of Sr(II), Cs(I), Ru(III), Pd(II), La(III), Nd(III), Sm(III), Gd(III), Zr(IV), and Mo(VI) was investigated by the batch method. Furthermore, the column test for Sr (II) was performed. The batch experiments were carried out by varying the shaking times, HNO₃ concentration, and initial concentration of metal ions. A relatively large K _d value above 182 cm³/g for Sr(II) was obtained in the presence of 3 M HNO₃. In contrast, the K _d values of Cs(I), Ru(III), Pd(II), La(III), Nd(III), Sm(III), Gd(III), Zr(IV), and Mo(VI) were considerably lower than 10 cm³/g. The adsorption of Sr(II) was found to be controlled by chemisorption mechanism, and followed a Langmuir-type adsorption equation. The breakthrough curve of Sr(II) had S-shaped profile, and the elution percentage was estimated to be 99.9% by using the eluent of H₂O.     

Preparation and preliminary evaluation of [^55Co]（II）vancomycin

Co-55 （t1/2=17.53 h） was produced by 150 uA irradiation of a natural nickel target using 15 MeV protons. It was separated from the irradiated target material by two ion exchange chromatography steps with a radiochemical yield of 〉95% and was used for the preparation of [^55Co]vancomycin （[^55Co]VAN）. Optimization studies were performed using Co-57 due to its longer half-life. Cobalt-57 （t1/2=271.79 d） was produced by irradiation of a natural nickel target with 150 pA current of 22 MeV protons. The 57Co was separated from the irradiated target material using a no-carrier-added method with a radiochemical yield of 〉97%. Both products were controlled for radionuclide and chemical purity. The solutions of [^55Co]VAN were prepared （radiochemical yield〉80%） starting with 55Co acetate and vancomycin at room temperature after 30 min. A precise solid phrase extraction （SPE） method was developed using Si Sep-Pak in order to purify/reconstitute the final formulation for animal studies. [^55Co]VAN showed a radiochemical purity of more than 99%. The resultant specific activity was about 1.15 TBq/mmol. It is proved that the tracer is stable in the final product and in presence of human serum at 37℃ up to 24 h. Biodistribution study of [55Co]VAN in normal rats was undertaken for up to 72 h.     

Uranium Extraction from Sea Water with Composite Adsorbents, (IV)

Composite hydrous titanium(IV)-iron(II) oxides prepared by precipitation from homogeneous solutions were studied with a view to developing magnetic adsorbents for uranium extraction from sea water.

Higher uranium adsorption capacity was registered with homogeneous than with heterogeneous solution used for preparing the oxide. The adsorbents for uranium prepared from homogeneous solution moreover were found to require the copresence of urea and a suitable anion such as SO^2- ₄, in order to provide strongly active adsorption of uranium.

The value of saturated magnetization of the composite hydrous oxides decreased with increasing titanium mole fraction up to 0.75, increase of the titanium mole fraction had, on the other hand, the effect of enhancing uranium adsorption capacity, which however saturated beyond 0.75 titanium mole fraction.

The change of enthalpy brought by the uranium adsorption on the composite hydrous titanium (IV)-iron (II) oxides was 10 kcal/mol, and the amount of change independent of the conditions of precipitation.     

A Method for Determination of Plutonium in Blood by Anion Exchange

The anion exchange behavior of Pu(IV) and Pu(VI) were studied in solutions of both nitric acid and of ethanol-nitric acid mixture, and a method of determining plutonium content in blood was developed. About 10 ml of blood were wet-incinerated with concentrated nitric acid and evaporated to dryness. The residue was dissolved in 8 ml of 8 N nitric acid, and 12 ml of ethanol was added. The solution was passed through a resin column of Dowex 2, X8 (9 mm diam., 3.0cm long). After washing the column with ethanol-nitric acid mixed solution, plutonium was eluted with 10 ml of 1N nitric acid containing sulfur dioxide. The eluate was transferred to a cell for electrodeposition, which was carried out with 500 mA/cm² for 3 hr using a stainless steel disk as cathode.

The plutonium yield from the ion exchange was 85~91%, and the electrodeposition quantitative. The blank activity from the reagents, resin and disk was 10^?14Ci. With this method a 10-hr count with silicone semiconductor spectrometer, will permit determination of 5 × 10^?14 10^?13Ci of plutonium in 10 ml of blood.     

Effect of Gamma-Irradiation on Cation Exchange Resin

Several forms of cation exchange resins with different crosslinkages have bsen subjected to ⁶⁰Co γ-radiation, in wet or dry state and the effects of such variables as adsorbed ionic species, crosslinkage of the resin, and the water content in the resin on radiation damage to organic resin have been examined in their relation to γ-radiation dose. The result showed that radiation caused marked changes in the chemical and physical properties of the resin, and phenomena such as de-crosslinking, loss of strong-acid capacity, formation of a functional group composed of a weak-acid exchange group were observed. The degree of such degradation phenomena was not affected by adsorbed ions when their valency states were kept unchanged during irradiation, but when the adsorbed ions were reduced during exposure, the extent of degradation was found inhibited to a significant extent. It may be concluded from the results that the decomposition of the cation exchange resin is mainly initiated by reaction with the resin produced by radiation-formed reducing species, i.e., H atoms. A mechanism of resin degradation is also proposed.     

Isolation of 137Cs with Copper Ferrocyanide-Anion Exchange Resin

The adsorption and desorption of ¹³⁷Cs on copper ferrocyanide-anion exchange resin, prepared in the manner previously reported in this Journal in a Short Note, are presented in detail.

This resin can also be used for the concentration of the ¹³⁷Cs found in sea water. The nuclide is adsorbed effectively on the resin from water, hydrochloric acid below 4 M, and on nitric acid below 1M. After adsorpsion on the resin, ¹³⁷Cs is eluted easily with either nitric acid (>6M), ammonium water, or silver nitrate solution.

Adsorption on the resin is specific for ¹³⁷Cs, and the action is due entirely to the ferrocyanide moiety of the resin.

This method is more efficient than the co-precipitation method with copper ferrocyanide for the concentration of radiocesium from a large volume of sea water.     

Analyses of Power Excursion Event in Chernobyl Accident with RETRAN Code

Nickel ferrite is one of the important corrosion products of PHWR's where Monel and carbon steel are used as the constructional materials in the primary heat transport system. The dissolution of synthetically prepared nickel ferrite was studied in low concentrations (<10 mmol/l) of HEDTA, DTPA, NTA and HIDA. The dependence of the dissolution rate on the ligand concentration was found to be langmuirian in all these cases. The effect of the addition of low concentrations of citric acid, oxalic acid, ascorbic acid and Fe(II)-ligand complex, individually, to each of the above chelating agents was also studied. The effect of pH and temperature on the dissolution rate was determined.     

Uranium Extraction from Sea Water with Composite Adsorbents, (III)

Measurements were made of the extent of magnetization shown by composite hydrous titanium (IV)-iron (II) oxide adsorbents for use in uranium extraction from sea water. The possibility of removing the adsorbent by means of high-gradient magnetic separation was demonstrated by calculations based on a force balance model.

Removal experiments were also carried out, which demonstrated that the composite hydrous oxide can be trapped effectively: A composite hydrous oxide with 1:1 Ti-to-Fe mole ratio, of 400–625 mesh particle size, proved to be removed to 99.9% by a magnetic field of 2.5 kOe, with the slurry flowing at 20 cm/s through a filter matrix 50 cm long packed to 90% void with 100 μm diameter nickel wire stuffing.

Together with the evaluations made of the electric power consumed by the high-gradient magnetic separators, the experimental results indicated the possibility of economically extractng uranium from sea water using these separators in combination with magnetic adsorbents.     

Incorporation of Radioactive Spent Ion Exchange Resins in Plastics

Experiments were undertaken on the incorporation in plastics—polyethylene in particular—of radioactive spent ion exchange resins produced in nuclear power plants. The resulting polyethylene products burdened with radioactive resin were tested to ascertain the properties considered important for radioactive waste management. The items chosen for testing were mechanical strength, leachability of radionuclide and radiation resistance. Polyethylene products burdened with 50w/o of resin were found to possess an impact strength of 10kg-cm/cm and a compressive strength of 300 kg/cm², which values do not indicate any appreciable decrease in mechanical strength compared with polyethylene unburdened with resin. The leaching rate of ¹³⁷Cs from the resin- burdened polyethylene product was very small—only 0.1% leached out in one year. In respect of decomposition by radiation, the amount of gases evolving upon absorbing a dose of 10⁹ rad was 10 ml/g. The effect of radiation on the mechanical strength was also studied.

It is concluded from above results that solidification of radioactive spent ion exchange resin by incorporation in plastics is one of the best methods devised so far for treating spent resins.