Treatment of radioactive liquid waste by sorption on natural zeolite in Turkey (original) (raw)
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Cleaning of liquid radioactive wastes using natural zeolites
Applied Radiation and Isotopes, 2000
Natural zeolite, clinoptilolite, was used to eliminate liquid radioactive wastes (LRW) 137 Cs and 90 Sr. The in¯uence of several factors (pH of solution, grain size of the zeolite, etc.) on the process eectivity was studied. It was shown that clinoptilolite is an eective ®lter of the nuclides above. #
Treatment of radioactive liquid waste using Iraqi geological raw materials and zeolite
Al-Nahrain Journal for Engineering Sciences, 2013
A radioactive liquid waste contaminated with cesium-137 was found underneath a destructed radioactive waste treatment station in Tuwaytha site 25 km south of Baghdad - Iraq.The appropriate sorbent materials found for the removal of radio cesium-137 were bentonite and modified bentonite with corresponding removal efficiencies of 85% and 91.8% respectively. The favorable batch experimental conditions were found to be 800 rpm stirring speed, 200 mg sorbent mass, 45μm sorbent particle size, and solution temperature of 30 oC for an initial radio cesium concentration of 0.44 mg/l.The BET isotherm model was found to represent the experimental results very well.
Decontamination and solidification of liquid radioactive waste using natural zeolite
Journal of Material Cycles and Waste Management, 2014
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2023
Radionuclides are widely known to produce serious problem when released and dispersed in the environment because they can contaminate humans through food chains, affecting metabolic process and causing health diseases to the population. A large amount of radionuclides is produced as waste during the process of nuclear facility operation, maintenance, and decommissioning. Wastewater contains many radioactivemetal ions. During the last three decades, after Chernobyl accident and then that of Fukushima, several techniques have been developed for the removal of radionuclides from the environment and from wastewater aiming of inertization. One of the most recent techniques, and in continuous progress, is the radionuclides removal by adsorption using natural and/or synthesized materials having high retention capacity and being resistant to radiation. The most used type of material, cheap and easy-to-find, is zeolite due to its high ion exchange capacity, adsorption efficiency and abundance. This work concerns a preliminary study on zeolites identification for the removal of radionuclides in wastewater samples from the fuel storage of the former nuclear power plant of Latina, Italy. The activity concentration of the radionuclides in the samples was investigated by γ-and α-spectrometry. The wastewater samples contain the radionuclides 137 Cs, 60 Co and 241 Am, and the best solution for their removal was discovered to be the zeolite A. The obtained results can be enlarged to all former Italian nuclear facilities.
Cs+and Sr2+adsorption selectivity of zeolites in relation to radioactive decontamination
Journal of Asian Ceramic Societies, 2015
Zeolites are used as adsorbents of cationic elements in the radioactive decontamination process of water, soil and others. We determined Cs + and Sr 2+ adsorption selectivity of some zeolites to know effective zeolite species for the decontamination of radioactive Cs and Sr. A 30 mL mixed solution containing up to 15 mg L −1 of non-radioactive Cs + or Sr + and up to 0.50 M of Na + or K + was mixed with 0.5 g of Lindetype A, Na-P1, faujasite X, faujasite Y and mordenite. Among the zeolites, mordenite had the highest Cs + adsorption selectivity, and the selectivity had no correlation to the cation exchange capacity (CEC) of the zeolites. In contrast, Sr 2+ adsorption selectivity of the zeolites positively correlated with the CEC of the zeolites; Linde-type A with the highest CEC showed the highest adsorption selectivity, and its adsorption rate was more than 99.9% even in the presence of 0.5 M K +. A simulated soil decontamination experiment of Cs from a Cs-retaining vermiculite by using mordenite and that of Sr from a Sr-retaining vermiculite by using Linde-type A showed decontamination rates of more than 90%.
The use of columns of the zeolite clinoptilolite in the remediation of aqueous nuclear waste streams
Journal of Radioanalytical and Nuclear Chemistry
Mud Hills clinoptilolite has been used in an effluent treatment plant (SIXEP) at the Sellafield nuclear reprocessing site. This material has been used to remove 134/137 Cs and 90 Sr successfully from effluents for 3 decades. Samples of the zeolite have been tested in column experiments to determine their ability to remove radioactive Cs + and Sr 2+ ions under increasing concentrations of competing ions, Ca 2+ , Mg 2+ , Na + and K +. These ions caused increased elution of Cs + and Sr 2+. Ca 2+ , Mg 2+ and K + were more effective competitors than Na +. For Na + , it was found that if concentration was reduced, then column performance recovered rapidly.
Separation and Purification Technology, 2002
Distribution coefficients of cesium on natural and cation-enriched (Na + , K + , NH 4 + and Ca + 2 ) forms of clinoptilolite were measured by batch, radioactive tracer technique. The measurements were carried out for an initial cesium concentration range of 10 − 6 -10 − 1 mol/dm 3 and at temperatures of 25, 40, 60 and 80°C. Experimental isotherms evaluated from distribution coefficients were fit to Langmuir, Freundlich and Dubinin-Radushkevich (D-R)models. Of the models tested, D-R model was found to represent the isotherms better in a wider range of concentrations than either Langmuir or Freundlich model. Breakthrough behavior of cesium on natural and cation-enriched forms of clinoptilolite for a particular set of conditions were also determined in a small size column. Column parameters were evaluated using mass transfer zone concept.
Separation and Purification Technology, 2012
Sodium nonatitanate is a layered material that contains exchangeable sodium ions between layers. Zeolite A is an aluminosilicate structure that also contains exchangeable sodium ions inside the silica and alumina tetrahedral ''cages''. Both of these inorganic materials are known to selectively trap divalent metals. This paper describes the preparation/characterization of these inorganic samples and a comparative study of their sorption properties. Several types of experiments were performed: first, the experimental conditions for the sorption properties were assessed; then, the thermodynamics of sorption were studied; and finally, these two sorbents were compared in actual radioactive solutions (with low salinity and then with high salinity to simulate liquid waste from the Fukushima site). The maximum sorption capacity, the selectivity for Na/Sr and Ca/Sr, and the adsorption exchange free energy were obtained for the sodium nonatitanate and zeolite A samples. Sodium nonatitanate exhibited satisfactory decontamination properties for solutions with low amounts of calcium and was less affected by the presence of sodium when the strontium content was low. Zeolite A samples were also good candidates for strontium decontamination but were less efficient in a strong saline effluent.
Radiochimica Acta, 2010
The purpose of the work was to improve the process for treatment of liquid radioactive waste containing complexing agents, which are generated during the decontamination operations. We performed some experiments using simulated waste solutions like secondary waste from the modified CANDEREM process (Canadian Decontamination and Remediation Process) and secondary waste from the modified CANDECON process (Canadian Decontamination Process). To improve efficiency and economics of the process it was proposed to treat the waste by combining the sorption of radionuclides on natural inorganic sorbents (zeolites) with membrane filtration. Standard procedures are applied to compare the sorption of radionuclides on different sorbent forms-determination of the ion exchange capacity, construction of sorption isotherms, determination of the distribution coefficients, and kinetics experiments. To check the influence of converting the sorbents to various cationic forms on their sorption properties, distribution coefficients of 137 Cs and 57 Co on natural zeolites from local deposits converted to NH 4 + , Na + or H + forms were determined. The results obtained show that the distribution coefficients of 137 Cs on the materials converted to Na + form are higher than for the remaining forms studied [1]. The parameters of Langmuir, Freundlich and Dubinin-Radushkevich adsorption isotherms have been determined using sorption data. The Dubinin-Radushkevich model shows better correlation between the theoretical and experimental data for 137 Cs sorption on natural zeolites from local deposits converted to NH 4 + and H + forms than Langmuir and Freundlich equations. Kinetic studies were carried out with various zeolite forms. The sorbents studied are natural zeolites from local deposits (Marsid-Romania). The batch sorption kinetics has been tested for pseudosecond order reaction. The pseudo-second order model fits the experimental data well for all of the systems studied.