Sorption Behavior of Cesium and Strontium Ions on Mixtures of Clay Sorbents

The sorption behavior of Cs and Sr ions on natural clay minerals such as sand, bentonite and loam, and mixtures of bentonite-sand and loam was studied under static condition.

It was found that the distribution ratio of Sr ion on bentonite and loam are influenced by loam concentration of solution, along with the concentration of ion of interest. The obtained results revealed that the distribution ratio of ion the clay mixture can be expressed,in terms of distribution ratio of each constituent of the mixed sorbent, provided that the corrections for pH and sorbed ion concentration of solution are made.     

Migration of Cesium,Strontium and Cobalt in Water-Saturated Inada Granite

Diffusivities of C_s, Sr and Co were measured in a water-saturated granite in an attempt to investigate the migration of radionuclides into the matrix of the rock. The measured penetration profiles of every tracer were composed of two parts. There were a steep slope near the surface and a gradual slope in the deeper part. These profiles were successfully explained by considering two diffusion paths in the granite. One diffusion path was fissure with a width of a few microns and another was network of submicron pores. The volume of submicron pores was approximately 80% of the total pore volume in the granite. The orders of magnitude of apparent diffusivities for all nuclides were 10^?11 to 10^?12m²/s through the fissure and 10^?14 m²/s through the network of pores. The ratio of geometrical factors in the two paths was also calculated from each apparent diffusivity and was almost unity. This calculated ratio suggests that the pore network in the granite matrix has a similar shape to the fissure, thus the microstructure of the granite seems to be fractal.     

用无机离子交换法从酸性高放废液中去除铯研究进展

60年代以来人们十分关注用离子交换法从配性高放废液中去除和回收∧137Cs。本文对比和评价了沸石、多价金属磷酸盐、磷钼酸铵及其复合离子交换材料、不溶性亚铁氰化物、钛硅化合物等无机离子交换剂。结合笔者的最新研究成果,并考虑了含铯废液交换剂的进一步处置问题,提出了为我国生产堆高放废液中去除∧137Cs的无机离子交换材料,对我国的后处理中去除铯的研究提供参考。     

Diffusion Behavior of Cesium,Strontium and Cobalt in Pellet Waste Package

A leaching model for a radioactive pellet package for nuclear power plant wastes was studied. Calculated results obtained in term of the model were compared with experimental ones, where volumetric averages of diffusion coefficients in the Na₂SO₄ pellet and in the cement-glass were used to solve the diffusion equation in the pellet package. Since Na₂SO₄ pellets dissolved quickly, the pellet part were simulated by saturated Na₂SO₄ solution. The leaching ratios were meaured with different volume ratios of cement-glass in the package to discuss the validity of the model. The cement glass diffusion coefficient and distribution factor, which were required to solve the equation, were also measured. The calculated results agreed with the experimental ones within a 20% error.     

Sorptive Removal of Cesium-137 and Strontium-90 from Water by Unconventional Sorbents

It has been shown that coal fly ash is a good adsorbent for both radionuclides of ¹³⁷Cs and ⁹⁰Sr. Radiocesium adsorption is maximal around the neutral region whereas radiostrontium adsorption increases with pH, especially above pH 8. Cesium retention sharply drops with ionic strength while strontium adsorption increases sharply and steadily at low and moderate concentrations of the inert electrolyte, respectively. The suggested mechanisms of radionuclide retention by fly ash is specific adsorption of Cs⁺ and irreversible ion-exchange uptake of Sr²⁺. The isotherm of adsorption is a Langmuir approximation of the B.E.T. multi-layered sorption. Acid pretreatment of fly ash, though not increasing radionuclide sorption capacity, may be useful in preventing the leach-out of other contaminants from the sorbent into water during the adsorption process.     

球形亚铁氰化镍钾聚丙烯腈吸附剂的制备及应用

制备了以聚丙烯腈(PAN)为骨架、亚铁氰化镍钾(KNiFC)为核心的球形复合吸附剂(KNiFC/PAN),并通过X射线衍射仪、金相显微镜和电感耦合等离子体质谱仪等手段对该吸附剂进行了分析表征。采用批式实验,研究了硝酸浓度、Na⁺、NH⁺₄、接触时间等对KNiFC/PAN吸附Cs⁺的影响,研究了吸附过程的反应动力学和吸附等温线。结果表明,该吸附剂对Cs⁺的典型吸附分配系数(K_d)为10⁴～10⁵ mL/g,平衡时间小于5 min;硝酸浓度小于1.0 mol/L时,K_d值基本不变,之后随酸度增加,K_d值逐步减小;随着Na⁺浓度增加K_d值逐步减小;NH⁺₄对Cs⁺的吸附有明显的竞争。KNiFC/PAN对Cs⁺的等温吸附较符合Langmuir模型,...     

Temperature Dependence of Cobalt Release Rate from Stainless Steel in Neutral Water

In order to evaluate the release source of Co from heated tubes of the feedwater line of BWR, Co release rate measurements were carried out by measuring ⁶⁰Co released from irradiated stainless steel in contact with neutral water at an oxygen concentration of 20 ppb. The temperature- and time-dependences on Co release rate were studied for 670 h release experiments; the rate was found to decrease in proportion to t ^?frac12 (t ^?frac12 (t: exposure time) and to have its maximum value around 240°C. An empirical equation was obtained for the Co release rates in the temperature range of 150~240°C.

R_Co = 1.9 × 10⁶ exp (-14,300/(RT)) t ^?frac12

where R _co Co release rate (mg/(dm²·month)), R: Gas constant (cal/(mol·deg.)), T: Exposure temperature (K) and t: Exposure time (h). Decrease in the Co release rate with temperatures over 250°C, seemed to be ascribed to the formation of a protective oxide layer on the surface of stainless steel.     

Extraction of Lithium from Sea Water with Metallic Aluminum

Extraction of lithium from sea water was investigated. It was found that a corrosion product of metallic aluminum immersed in sea water extracts lithium from it selectively. Effects of the temperature and the pH of sea water, and of the initial concentration of lithium in it were examined. On the basis of the analysis of the surface deposit on aluminum, which is a corrosion product of aluminum, the selectivity coefficients were calculated. For the extraction of lithium from natural sea water, the values of K ^Li _Na ^Li _MgK ^Li _Ca and ^Li _K were 9.9 × 10², 1.1×10, 4.5×10 and 4.4 × 10², respectively.     

Development of a Technology for Removing Europium from Spent-Fuel Holding-Pond Water at the Beloyarsk Nuclear Power Plant

A purification technology using a coagulant followed by filtration through bulk layers of inorganic selective sorbent Termoksid-3A, cationite KU-2-8chs, and anionite AV-17-8chs has been developed for reducing the europium activity of the water in the holding pond of the No. 3 unit at the Beloyarsk nuclear power plant. The coagulant consisted of active aluminum hydroxide with concentration 2.5 mg/liter with respect to aluminum. The coagulant and most of the radionuclide mass were removed using Termoksid-3A sorbent. Additional removal of radionuclides and electrolytes occurs on bulk layers of anionite and cationite; these layers also maintain the water regime parameters – the electric conductivity, the chloride concentration, and other indicators – within the prescribed range. The coagulant accumulated on the Termoksid-3A sorbent is removed periodically by counterflow agitation washing. This technology has been tested on a model system simulating the main components and parameters of the proposed scheme.     

Extraction of Uranium from Sea Water by Method of Dispersion and Deposition

The extraction of uranium from sea water by the adsorption on the mixture of titanic acid and bentonite making the uranium rich deposit on the sea bottom is described. The purpose of this work is the minimization of energy required for contacting the vast volume of sea water with the adsorbent. Unique features of bentonite are applied to the coagulation of adsorbent forming the particles of suitable size in the sea water to make uranium rich deposit on the sea bottom close to the land. The concentration of uranium in the deposit is about 380 times that of sea water, and the loss of titanium is about 2% of the total amount of titanium which is used with the bentonite of ten times as much as it.

The depths of sea necessary to make uranium rich deposit for the various conditions were calculated and the result was obtained that 50 m was sufficient for this method. As a trial of the second stage of concentration of deposited uranium, the continuous RIP method was carried out in counter-current fluidized bed which was operated without reversal of flow.

The results reported in this paper are based on the laboratory scale experiments using the artificial sea water and on the calculations concerned with the rate of adsorption in agitated systems.     

Sorptive Removal of Cesium-137 and Strontium-90 from Water by Unconventional Sorbents. I. Usage of Bauxite Wastes (Red Muds)

Bauxite wastes of alumina manufacture, i.e., red muds, have been tested for radiocesium and strontium removal from water. The red muds were water-washed, acid-, and heat-treated before usage to produce hydrous oxide like sorbents. Surface treatment of the sorbent was benefical for ¹³⁷s uptake, while heat-treatment was detrimental to the -SOH surface sites responsible for high ⁹⁰Sr affinity. Fractionation of the sorbent with respect to apparent grain size did not produce significant differences in the sorption efficiency. The distribution coefficients vs. equilibrium activity in solution showed a maximum with Cs, and a gradual decrease trend with Sr. The solution activity vs. adsorption data were fitted to B.E. T. (essentially types IV-V) isotherms for Cs and B.E. T.-Langmuir isotherms for Sr. Desorption, temperature-, pH-, and ionic strength-dependence tests revealed that the primary mode of sorption for both cations is specific adsorption while the secondary mode is ion exchange. A rise in pH favours the ion- exchange sorption of Sr while the specific adsorption of Cs is negatively affected. Competitive adsorption of an inert electrolyte, i.e., NaCl, severely hinders Cs sorption, while Sr sorption on water-washed red mud is not significantly affected.     

从高放废液中萃取铯的杯冠化合物的研究进展

文章概要综述了与从高放废液中去除铯离子有关的杯冠化合物的合成方法和对金属离子的配位识别能力及分子模拟等方面的研究进展情况。 1 ,3 杯 [4]冠 6化合物对铯离子呈现出很强的络合能力 ,是分离铯离子的性能优异的新型萃取剂。     

植物碳同位素组成的环境影响因素及在水分利用效率中的应用

碳同位素值（δ13C）综合反映了植物光合作用过程中气孔的传导和CO2的固定,可以作为植物在环境中生理机能变化的指标,应用于研究植物生理与生态环境之间的关系。本文主要讨论植物碳同位素组成在不同环境中的变化,并对影响程度和机理进行了探讨。降水、温度、光照、土壤盐度、大气CO2浓度等不同程度影响植物的气孔传导和CO2的固定,植物的δ13C值相应产生不同的变化。降水因素对δ13C值影响最明显,温度对δ13C值产生的影响较复杂。一般情况下,大气中CO2都是通过影响植物叶片的内外压力,造成植物碳同位素值的差异。由于δ13C值不仅可以反映植物在光合作用过程中水分的利用,而且,δ13C值与水分利用效率具有正相关性,因此,碳同位素技术应用于植物生态研究中。     

除Sr、Cs无机交换剂的制备及性能

为去除废液中的Sr、Cs等裂变产物,用制备的亚铁氰化铜钾和亚铁氰化钴钾无机交换剂进行了初步研究。结果显示,亚铁氰化铜钾交换剂对Sr、Cs离子的静态饱和交换容量最大值分别为80、160mg／g,对Sr、Cs离子的动态交换容量最大值分别为17、130mg／g;亚铁氰化钴钾交换剂对Sr、Cs离子的静态饱和交换容量最大值分别为80、70     

Catalytic Effect of Activated Carbon and Activated Carbon Fiber in Non-Equilibrium Plasma-Based Water Treatment

Catalysis and regeneration efficiency of granular activated carbon （GAC） and activated carbon fiber （ACF） were investigated in a non-equilibrium plasma water treatment reactor with a combination of pulsed streamer discharge and GAC or ACF. The experimental results show that the degradation efficiency of methyl orange （MO） by the combined treatment can increase 22% （for GAC） and 24% （for ACF） respectively compared to pulsed discharge treatment alone, indicating that the combined treatment has a synergetic effect. The MO degradation efficiency by the combined treatment with pulsed discharge and saturated GAC or ACF can increase 12% and 17% respectively compared to pulsed discharge treatment alone. Both GAC and ACF show catalysis and the catalysis of ACF is prominent. Meanwhile, the regeneration of GAC and ACF are realized in this process. When H202 is introduced into the system, the utilization efficiency of ozone and ultraviolet light is improved and the regeneration efficiency of GAC and ACF is also increased.     

Elution Behavior of Cesium from Ferrierite Column by Using Inorganic Salt and Acid Solutions

The distribution coefficient (K_d) of Cs on ferrierite decreased with increasing concentration of the coexisting inorganic cations in the order of Na⁺>H⁺>K⁺>NH₄ ⁺. A linear relationship with a slope of about —1 was obtained between log K _d and log[M⁺] above 0.1M (=mol/dm³). The retention volume (V _R ) of Cs in chromatography also decreased in a similar manner to K _d , depending on the kind of inorganic cations. The V _R value can be predicted from the K _d value based on the linear relation. The column efficiency was improved with fine particles of ferrierite, yielding the elution percentage above 95%.     

分离铯的吸附剂焦磷酸氧锆的合成与表征

合成了分离铯的吸附剂焦磷酸氧锆,比较了不同条件下制备的焦磷酸氧锆对铯的吸附性能,并对吸附性能好的焦磷酸氧锆进行了分析与表征。结果表明,在不同条件下制备的焦磷酸氧锆对放射性铯的吸附率相差不大。焦磷酸氧锆化学式为［3ZrO•2HP₂O₇］_n•8.6nH₂O, 为无定型物质,具有良好的热稳定性, 最可几孔径约为1.5 nm,比表面积为180.7m²/g。     

新型铯选择性吸附剂的合成及性能

在金属镍粉表面原位合成了与金属基体紧密结合的亚铁氰化镍钾(KNiFC/Ni)吸附剂。经分析,其表面为面心立方晶系的亚铁氰化镍钾(KNiFC),厚度约为40~80nm,晶格参数为0.996 0nm,化学组成可表示为K1.4Ni1.3Fe(CN)6。结果表明:该吸附剂不水解,对137 Cs具有较高的吸附容量,非常快的吸附速率,很高的选择性,Cs的吸附分配系数(Kd)可达105 mL/g,即使在1.0mol/L NaNO3溶液中,Kd值也大于103 mL/g;该吸附剂吸附137 Cs为典型的离子交换机制,NH+4由于具有和Cs+相近的离子半径所以竞争最为强烈。本吸附剂有望用于含铯废液的处理及137 Cs的分离或提取。