Improvement of the novel method for decontamination of the radioactive aqueous solutions (original) (raw)
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International Journal of Environmental Science and Technology, 2018
Upon incorporation of iron oxide particles into calcium alginate gels, composite magnetic materials called ferrogels can be obtained. It has already been found that the alginic ferrogel sorbent can be applied for purification of aqueous solutions containing ions of various heavy metals. In present paper, batch sorption experiments were carried out to remove radionuclides of caesium(I), strontium(II), europium(III) and americium(III) from aqueous solutions. The recovery of the radioactive metals was achieved by direct dosing of sodium alginate/iron carbonyl, followed by stirring the system for 2 h. The process was investigated as a function of the following parameters: pH, initial concentration of calcium ions and the amount of the dispersed iron in the 2% (w/w) aqueous solution of sodium alginate. The optimum conditions were: 15 g/L of iron carbonyl suspended in 1 L of aqueous solution of sodium alginate and about 20 g CaCl 2 added to 1 L of the solution containing the radiometals. The results revealed that trivalent Am-241 was totally eliminated. Also trivalent Eu-152/154, divalent Sr-85 and monovalent caesium-137 were removed with the efficiency of about 80, 50 and 30%, respectively. It was found that exchange of calcium chloride with other metal salts does not influence significantly the removal efficiency. Laboratory-scale pilot experiments have shown that with aim to purify water, excess of the gelling agent can be removed with the method of nanofiltration.
Material science & engineering international journal, 2024
The article is devoted to the development of nanoscale sorbents based on copper ferrocyanide and magnetites for the removal of cesium, strontium, and heavy metal ions in their simultaneous presence in a multicomponent two-phase low-level radioactive solution containing complexing agents and surfactants. It they noted that the highest values of cesium ion removal from low-level radioactive water-99.96% and 99.62%-are obtained with sorbents based on 100% copper ferrocyanide and a mixture of copper ferrocyanide and industrial magnetite in a ratio of 2 to 1. The efficiency of the sorbents in terms of the distribution coefficient is 2394 and 1589.7 ml/g, which ensures the purification of radioactive water from trace concentrations of cesium ions to values of 2394 and 265.11. These sorbents provide water purification to values less than 2 Bq/cm 3 , which is typical for 1-4 classes of water quality in terms of radiation safety of groundwater and surface water as sources of centralised drinking water supply. It is noted that sorption of cesium ions on copper ferrocyanide and magnetite is carried out in the presence of water molecules and hydroxo groups. It is shown that artificial magnetite in its pure form exceeds the sorption capacity of industrial magnetite. This is due to the difference in the phase composition and particle size of the crystals. The results obtained will be use as components of the technological process in the Plasma-Sorb technology developed at the State Institution "The Institute of Environmental Geochemistry" of the National Academy of Sciences of Ukraine for the treatment of low-and intermediate-level radioactive water from Ukrainian nuclear power plants.
Magnetic composites as an effective technology for removal of radioactive cesium
International Journal of Environmental Science and Technology, 2015
Radioactive cesium (137 Cs) has seriously become a human concern owing to exposure from a nuclear accident release at a nuclear plant. Many efforts have focused at the removal of radioactive cesium and remediation of a contaminated environment. To meet these demands, an effective sorbent based on magnetic composites functionalized with synthetic clay minerals was demonstrated. This sorbent shows a high removal efficiency of contaminated water containing suspended sorbents at a level of 0.5 mg ml-1 [ 137 Cs of 84.68 Becquerel (Bq) gram (g)-1 ], decontaminated to 0.47 Bq g-1 (99.44 % removal efficiency) with just one treatment. The radioactive cesium is dramatically adsorbed into synthetic clay minerals. Subsequently, a rapid and easy sorbent separation from the radioactive cesium solution occurs after treatment using a magnetic field. Thus, a magnetic sodium-phlogopite sorbent can offer high potential for in situ remediation.
Journal of Environmental Analytical Chemistry, 2014
Three different types of natural sorbents were developed using natural siliceous material, sodium alginate, and impregnation of goethite in alginate matrix. Experiments were carried out for decontamination of uranium, thorium, americium and plutonium by using siliceous material, Calcium-Alginate (Cal-Alg) and Goethite impregnated Calcium-Alginate (Geo-Cal-Alg) respectively. These materials were tested for different conditions by varying their pH in the range of 1-8, 95-98% Am-241 and Pu-239+240 sorbed by Cal-Alg and Geo-Cal-Alg beads respectively and experimental sorption capacity as evaluated were Eu 3+ as a natural analogue for Am-241 and Pu-239+240 is 12.16 mg g-1. Experimental results clearly showed that Th and U sorption capacity is 1 and 0.3 µg mg-1 (w/w) respectively in case of siliceous material. No change in various physicochemical characteristics of the potable water was observed after decontamination process.
Proper management of certain radionuclides is necessary for clean, safe and secure radioactive waste management, both at commercial Nuclear Power Plants (NPPs) and at Department of Energy Environmental Management sites (DOE-EM). Selective removal of specified isotopes through ion exchange is a proven treatment method for liquid waste, yet various aspects of existing technologies leave room for improvement with respect to both cost and effectiveness. In order to be good candidates, novel media must exhibit exceptional primary figures of merit, namely ion exchange capacities and distribution coefficients (Kd), but also superior secondary figures of merit, such as thermal, chemical and radiation stability. The secondary figures of merit are rarely exhibited by the state-of-art Ion Exchangers, based on Organic materials. We herein report new data on the extended family of Inorganic Ion Specific Media (ISM): Surfactant Modified Media (SMM) and Surfactant Modified Zeolites (SMZ). The diff...
Sorption-Assisted Ultrafiltration Hybrid Method for Treatment of the Radioactive Aqueous Solutions
Chemistry
The paper presents results of studies on the possibility of using the ultrafiltration method supported by sorption on low-cost, easily accessible aluminosilicates to purify water contaminated with radionuclides. An aqueous solution contaminated with radionuclides in the form of cations at different oxidation states—Cs(I)-137, Co(II)-60 and Am(III)-241—as well as pertechnetate anions—TcO4−-99m—was treated by the proposed hybrid method. In the presented work, the influence of the important process parameters (i.e., pH, sorbent dosage, temperature and feed flow rate) on the removal efficiency of radionuclides was studied. The obtained results showed that hazardous impurities, both in the form of cations and anions, may be effectively removed from water by the application of sorption-assisted UF (SAUF) using the clay-salt slimes as a sorbent. As a final stage of the work, we treated the simulated liquid radioactive waste using the SAUF method, also showing satisfactory results in its pu...
Radioactive liquid waste treatment is a subject that have received considerable attention worldwide in recognition of its importance for the protection of human health and the environment from adverse effects of radiation associated with these wastes. In this work, the radioactive waste management policy principles will be presented briefly, and an overview of proven liquid radioactive waste treatment technological options and approaches and their alternative designs will be provided, as part of an integrated waste management system. The paper will focus on the development of the sorption technique, as one of the most widely used techniques for the treatment of liquid radioactive wastes, presenting some of the latest important results and giving a source of up-to date literature on it. The progress in utilizing different sorbents in radioactive liquid waste treatment will be highlighted. Moreover, the most important aspects referring to new trends and visions in the application of these sorbents in liquid radioactive wastes treatment are overviewed.
Enhanced removal of dissolved metal ions in radioactive effluents by flocculation
International Journal of Mineral Processing, 2006
Decontamination of radioactive effluents of low or intermediate level of radioactivity generated from different nuclear industries is done through the chemical precipitation route. The precipitates thus formed are of very fine sizes thereby requiring flocculation for faster settlement. The presence of polyacrylamide-based polymer not only enhances settling velocity but also increases removal of dissolved non-radioactive as well as radioactive metal ions from the liquid. About 99.5% of Cu 2+ and Fe 3+ ions are removed due to the presence of cationic Rishabh 611. Flocculation by either cationic or anionic flocculant has shown improvement in removal of radioactive strontium while turbidity of the liquid is reduced to a very low value (0.8 NTU). Decontamination factors (DF) of the effluents from different plants are improved by 3-5 times.
Radiochimica Acta, 2014
The use of composite materials based on metal ferrocyanides combined with natural mineral sorbents for treatment of high salinity Cs-containing liquid radioactive waste (LRW) was investigated. The study indicated that among the investigated composites, the best sorption characteristics for Cs were shown by materials based on copper ferrocyanide. Several factors affecting the removal of cesium from LRW, namely total salt content, pH and organic matter content, were also investigated. High concentrations of complexing organic matter significantly reduced the sorption capacity of ferrocyanide sorbents.
Journal of Hazardous Materials, 2009
The volumes of low level waste (LLW) generated during the operation of nuclear reactor are very high and require a concentration step before suitable matrix fixation. The volume reduction (concentration) is achieved either by co-precipitating technique or by the use of highly selective sorbents and ion exchange materials. The present study details the preparation of cobalt ferrocyanide impregnated into anion exchange resin and its evaluation with respect to removal of Cs in LLW streams both in column mode and batch mode operations. The Kd values of the prepared exchanger materials were found to be very good in actual reactor LLW solutions also. It was observed that the exchanger performed very well in the pH range of 3-9. A batch size of 6 g l −1 of the exchanger was enough to give satisfactory decontamination for Cs in actual reactor LLW streams. The lab scale and pilot plant scale performance of the exchanger material in both batch mode and column mode operations was very good.