Removal of radionuclides from low level radioactive liquid waste by precipitation

Six elements in several organs of mice fed with Zn deficient diet (Zn-def. mice) and those fed with control diet (control mice) were analyzed by INAA. Zinc concentrations in the organs of Zn-def. mice were not distinctly lower than those of control mice except for bone and pancreas. However, Ce content increased significantly in all organs of Zn-def. mice compared with control mice, indicating the partial substitution of Co with Zn in metal proteins or other materials for the Zn-def. mice.     

Removal of Arsenazo-III from liquid radioactive waste by cloud point extraction

Optimization of a method, based on thermal oxidation using a tube furnace system (Pyrolyser), for the separation of organically bound tritium (OBT) from environmental matrices is discussed. Results show that a maximum of ~?4 g of the vegetation sample, typical wild plant leaves of tropical regions, and ~?8 g of sediment sample can be combusted efficiently in the pyrolyser system. The recovery of OBT from wheat sample was observed to be ~?92% and that for sediment sample was ~?88%. The minimum detectable activity (MDA) at 95% confidence level was 3.4 Bq kg^?1 for a sample weight?=?4 g, counting time?=?30,000 s, and detection efficiency?=?23%.

     

Removal of Thoron and Arsenazo III from radioactive liquid waste by sorption onto cetyltrimethylammonium-functionalized polyacrylonitrile

A surfactant-functionalized polyacrylonitrile (SFPAN) was synthesized in the present investigation via gamma radiation-induced polymerization and was applied for sorbing two hazardous organics, Thoron (TH) and Arsenazo III (ARIII), from radioactive liquid waste. Efficient removals were achieved for both organics over a wide range of pH. The sorption kinetic studies of TH and ARIII revealed that the equilibrium time is significantly dependent on the solution pH. Among the tested sorption kinetic models, the kinetic data of TH and ARIII fit well to the pseudo-second-order one. The sorption equilibrium data obtained for TH and ARIII were analyzed using Freundlich, Langmuir, Temkin and Dubinin–Radushkevich (D–R) isotherm models. The obtained results demonstrated that the equilibrium data are well described by Freundlich and D–R models. The calculated values of the sorption energy (E) and the Gibbs free energy change (ΔG ^o) suggested that the sorption process of TH and ARIII onto SFPAN is governed by physisorption. SFPAN was further tested for the uptake of the concerned organics from radioactive process wastewater. The obtained results suggest its applicability for the treatment of liquid organic radioactive wastes.     

Concentration of radioactive components in liquid low-level radioactive waste by membrane distillation

The paper addresses some aspects of liquid low-level radioactive waste (LLLW) purification. Since the volume of liquid low-level wastes is usually large and the activity is rather low, the radioactive substances separated from the non-active portion have to be concentrated into the small volume for subsequent conditioning and disposal. The need for the improvement of decontamination and minimisation of the costs have led to new specific methods being under examination and development. The method proposed in the paper is membrane distillation. The experimental work described below supports the statement that membrane distillation can be an attractive alternative for liquid radioactive waste treatment. The advantages of membrane distillation over the other processes commonly used for the processing of LLLW are discussed in the paper.     

Recovery of cesium from intermediate level liquid radioactive waste

The antioxidant Lowinox 22M46 (Naftonox 22M46) were used for the extraction of cesium from intermediate level liquid radioactive wastes.     

In situ electrosynthesis of magnetic Prussian blue/ferrite composites for removal of cesium in aqueous radioactive waste

Journal of Radioanalytical and Nuclear Chemistry - In this study prussian blue (PB)/ferrite composites by in situ electrosynthesis were used to remove cesium (Cs) from aqueous radioactive waste....     

Treatment of simulated liquid radioactive waste containing cobalt by in-situ co-precipitation of Zn/Al layered double hydroxides

Journal of Radioanalytical and Nuclear Chemistry - This paper reports a new approach to treat the cobalt containing wastewater by in situ co-precipitation of Zn/Al layered double hydroxides (LDHs)....     

Denitration of simulated radioactive liquid waste

Journal of Radioanalytical and Nuclear Chemistry - Radioactive liquid wastes containing large amounts of nitric acid (approx. 4–7 M) generated in the nuclear fuel cycle are very...     

Removal of60Co and134Cs from radioactive process waste water by flotation

The removal of¹³⁴Cs and⁶⁰Co from radioactive process waste water using cetyl pyridinium chloride (CPC) as a collector and cobalt(II) hexacyanoferrate(II) as a precipitant for⁶⁰Co and sorbent (ion exchanger) for¹³⁴Cs was intensively investigated and the best removal conditions could be established. The results indicate that under the optimum conditions removals higher than 96% and 97% could be achieved for Co(II) and Cs(I), respectively. Cobalt(II) hexacyanoferrate(II) was found to have high affinity for cesium and can preferentially remove it in presence of relatively high amounts of other alkali or alkaline earth cations. A two-stage flotation process was successfully tested for the removal of both Cs(I) and Co(II) from waters containing both cations.     

Removal of methylene blue by tea wastages from the synthesis waste waters

The tea wastages could remove methylene blue（MB） as a cationic dye from waste water corresponding to second-order kinetic model.Thermodynamic studies showed that adsorption equilibrium constant（K_L） and maximum adsorption capacities(Q_max) were increased with increasing temperature.The removal efficiency of MB for Co 0.01 mmol/L at optimum conditions was about 85%. The maximum uptake capacity(Q_max) of methylene blue in a batch reactor was 0.328,0.542 and 0.659 mmol/g at 15,25 and 40℃, respectively.The enthalpy change（ΔH） and entropy change（ΔS） were 11.356 kJ/mol and 20.563 J/（mol K）,respectively.     

Separation of cesium from intermediate level liquid radioactive waste by solvent extraction with antioxidants

The intermediate level liquid radioactive wastes (RAW) isussed from nuclear power plants have high salt contents ca 200 g·dm^–3, the pH of liquid RAW being 12.5–13.7. A convenient method for separation of cesium under these conditions is solvent extraction with substituted phenols. For this purpose weere tested antioxidants produced in Czechoslovakia: AO 2246 [2,2-methylene-bis-(4-methyl-6-tertbutyl)phenol]; AO 4 [2-tertbutyl-4-(2-phenylpropyl)phenol]; AO 4K [2,6-ditertbuty-4-methylphenol]; AO 301 [2,2-methylene-bis-(4-{2-phenylpropyl}-6-tert-butyl)phenol]; and one antioxidant imporoted from Japan—NOCRAC 2246. This antioxidant is equivalent to AO 2246. After the first experiment it was found that the extraction efficiency for antioxidants AO 4 and Ao 301 is very low and the following experiments were made with AO 2246 (NOCRAC 2246) and AO 4K. Some effects on extracton as, pH of water phase, influence of diluent, influence of concentration of antioxidants, extraction time, were studied. The best results gave antioxidant NOCRAC 2246 in nitrobenzene, the extraction efficiency was 92.3% with pH 13.23.     

AHOT/异辛烷反胶束体系制备铁酸钴纳米粒子

分别以阴离子表面活性剂二(2-乙基己基)丁二酸酯磺酸钠(AOT)和新型表面活性剂二(2-乙基己基)羟基丁二酸酯磺酸钠(AHOT)与异辛烷/水构建的反胶束体系为微反应器,合成了CoFe2O4纳米粒子;利用TGA,XRD,TEM等手段对产物进行了表征;讨论了两种表面活性剂构建的反胶束体系对产物合成过程及纳米粒子形貌和尺寸的影响.     

Facile polyol synthesis of ultrasmall water-soluble cobalt ferrite nanoparticles

A facile protocol to prepare ultrasmall citrate-coated cobalt ferrite NPs was proposed from the comparison between one-step and two-step chemical routes based on the polyol method. Infrared spectroscopy, thermogravimetry and zeta potential data indicated different coordinations of citrate groups affecting the NP colloidal stability. The magnetic core size and saturation magnetization were also affected. The surface-modified NPs prepared by the one-step route presented superior colloidal stability, low core (2.9 nm) and hydrodynamic (4.8 nm) sizes, high magnetization (45 emu/g), and can be considered suitable platforms to produce nanoparticle-biomolecule conjugates.     

Measurement of63Ni in highly radioactive Hanford waste by liquid scintillation counting

Characterization of high-activity radioactive waste stored in underground tanks at Hanford requires determining⁶³Ni (100 y). This low-energy -emitter (E_max 67 keV) must be separated with a high degree of radiochemical purity large amounts of other fission and activation products. The method to be discussed involves multiple precipitation steps with several holdback carriers added, followed by precipitations with dimethylglyoxime, ion exchange, and electrodeposition. The⁵⁹Ni activity is determined by low-energy photon spectrometry. The sample is then stripped from the counting disk with HNO₃, converted to the chloride form, and the⁶³Ni -spectrum is measured with high efficiency by liquid scintillation counting.Pacific Northwest Laboratory is operated for the U.S. Department of Energy under Contract DE-AC06-76RLO-1830.     

Modern state of underground storage of liquid radioactive waste

Underground storage of liquid radioactive waste (LRW) has been successfully carried out in Russia over the past 40 years. Stages of development of the technology, its realization and chemical transformations of LRW components are considered and discussed, as well as the modern approach to underground storage. Control of the state of waste products and migration radionuclides and toxic compounds remains the key issue of providing safety of LRW storage. Radiation thermal and biochemical transformations of components of waste form new chemical compounds and, first of all, gases. The formation of gases is one of the important factors determining the safety of underground LRW storage.     

Treatment of radioactive liquid organic waste using bacteria community

Waste management plays an important role in radioactive waste volume reduction as well as lowering disposal costs and minimizing the environment-detrimental impact. The employment of biomass in the removal of heavy metals and radioisotopes has a significant potential in liquid waste treatment. The aim of this study is to evaluate the radioactive waste treatment by using three different bacterial communities (BL, BS, and SS) isolated from impacted areas, removing radioisotopes and organic compounds. The best results were obtained in the BS and BL community, isolated from the soil and a lake of a uranium mine, respectively. BS community was able to remove 92% of the uranium and degraded 80% of tributyl phosphate and 70% of the ethyl acetate in 20 days of experiments. BL community removed 81% of the uranium and degraded nearly 60% of the TBP and 70% of the ethyl acetate. SS community collected from the sediment of São Sebastião channel removed 76% of the uranium and 80% of the TBP and 70% of the ethyl acetate. Both americium and cesium were removed by all communities. In addition, the BS community showed to be more resistant to radioactive liquid waste than the other communities. These results indicated that the BS community is the most viable for the treatment of large volumes of radioactive liquid organic waste.     

Removal of137Cs from an intermediate level liquid waste by using various ion-exchange media

An intermediate level liquid waste (ILLW or Category III waste) stream was treated for the removal of radioactive Cs in pilot scale experiments, using three different ion exchange media. Results indicated that the polyacrylic fibre coated with cupric ferric hexacyanoferrate (CuFeHCF-fibre composite) was the most efficient, followed by cupric hexacyanoferrate loaded ion exchange resin (CuHCF-resin) and mixed zeolites (AR-1, 4A and 13X in the ratio 6:1:1). The mixed zeolites column and the CuFeHCF-fibre column were used in series in order to get a high total decontamination factor (DF). Leaching studies on the CuFeHCF-fibre composite loaded with¹³⁷Cs, in demineralised (DM) water, tap water and ground water media indicated a release of about 19.3%, 25.5% and 41.3% of¹³⁷Cs, respectively, in a period of about 8 months. XPS studies with CuFeHCF-fibre composite indicated some chemical interaction between the CuFeHCF precipitate and the polyacrylic fibre. Some of the possible disposal options for the CuFeHCF-fibre composite have also been discussed.     

Synthesis and electrochemical investigation of spinel cobalt ferrite magnetic nanoparticles for supercapacitor application

Cobalt ferrite magnetic nanoparticles (CoFe₂O₄-MNPs) were synthesized by hydrothermal and co-precipitation methods using different precursors such as nitrates, chlorides, and acetates, at different concentrations with/without surfactant under different growth conditions. The structural and morphological analyses reveal the formation of a single-phase CoFe₂O₄ in nanoplatelet-shaped NPs with average particle size between 11 and 26 nm depending on synthesis condition. The specific surface area of these NPs obtained by hydrothermal method was ~ 34 m² g^?1. Electrochemical performances of the obtained nanoparticles in a three-electrode configuration with a 6 M KOH electrolyte revealed a specific capacitance (C _s) of 429 F/g at 0.5 A/g, with excellent capacitance retention of 98.8% after 6000 cycles at 10 A/g for the electro-active NPs synthesized by hydrothermal method at 200 °C for 18 h.     

Studies on adsorptive removal of radioactive cobalt from alkaline waste generated in sodium cooled fast breeder reactors

The removal of radioactive cobalt from alkaline waste containing sodium has been studied in batch process using two different inorganic compounds (a) hydrous manganese oxide (HMO), and (b) copper hexa-ferrocyanide (CFC) and compared with a strongly acidic cation exchange resin (Dowex50W×8). The percentage removal of cobalt was examined by varying experimental conditions, viz. pH of the solution, contact time and interfering ions. The studies showed that HMO can be used as an efficient adsorbent for the removal of cobalt from sodium containing wastes.