| With the development of the nuclear industry, nuclear waste disposal is gradually coming into view, people give more and more attention to environmental problems by the rapid development of the nuclear industry. In 2011, Fukushima nuclear accident occurred in Japan is awakened public concern about nuclear aspects. Until today, the accident at Japan's Fukushima nuclear leakage accident resulting effect is still a profound impact on people nearby.Cesium-137 and strontium-90 are the main artificial radionuclides discharge in nuclear accident, particularly 90 Sr and 137 Cs can be getting into living organisms by the food chain, and this two artificial radionuclides have the longer physical half-period, also marine life and human security will be more obvious hazards. Because of putting forward higher requirements for the safety of the marine nuclear environment, concentration monitoring of 90 Sr, 137 Cs gets more attention in seawater beyond the current rapid construction of nuclear power plants at China's coastal marine nuclear safety a higher demand environment.By relevant studying and investigation in this paper, according to Japan's Fukushima nuclear leakage accident in emissions of 90 Sr, 137 Cs monitoring data, and according to the standard classification of radioactive waste(GB9133-1995) for the removal of reference to evaluate the effect. we used zeolite the experimental study of the removal of Cs and Sr in simulated seawater, discussed the process of adsorption in the adsorption isotherms, adsorption kinetics and adsorption thermodynamics, and environmental factors(temperature, pH, initial concentration and adsorbent dosage) on the adsorption were studied. The main conclusion of this paper are as follows:1. The experimental results were characterized by infrared spectroscopy and X-ray diffraction analysis. FTIR results showed that the adsorption characteristics and structural differences before and after the zeolite structure. For the first time by X-ray diffraction film filter drip method to characterize the Cs+ and Sr2+ two elements, and within the scope of the test results and test pipette errors were allowed. X-ray diffraction film filter drip method Cs+ and Sr2+ linear coefficient of two elements, analysis and testing of the standard curve were 0.9998 and 0.9999, linear correlation good,and recovery within the allowable range 80%~120%, X-ray diffraction film filter drip test method for analysis of Cs+ and Sr2+ relative standard deviation of 3% and 4%.2. Selected zeolite, diatomaceous earth and attapulgite three types of absorbents for comparison experiments, experiment results show that zeolite removal Cs+ and Sr2+ is much larger than the other two adsorbents. Zeolite as adsorbent, research in simulated seawater zeolite Cs+ and Sr2+ two elements removal, discussed the influences of adsorption time, the solution pH, adsorbent dosage and Cs+ and Sr2+ two elements initial concentration to the adsorption. The results show that: in simulated seawater zeolite adsorption of Cs+, 24 h front belongs to the fast absorption, when adsorption time reached 120 h, adsorption equilibrium is reached, the adsorption capacity is 33.2mg g, the removal rate nearly reached 50%. In simulated seawater zeolite adsorption Sr2+ in front 8h belongs to the fast adsorption, when the time reaches 24 h, have tended to achieve adsorption equilibrium, adsorption capacity is 41.7mg/g. Sr2+ removal rate close to 100% at the time of the adsorption equilibrium, with pH value of the solution increases, and adsorption capacity increases. With adsorbent dosage increased, adsorption capacity decreased, removal rate increased by adsorption capacity increased. With initial concentration increased, Cs+ and Sr2+ of zeolite removal rate increased in simulated seawater.3. The adsorption isotherm studies have shown that: the linear correlation coefficient Cs+ and Sr2+ are good in Langmuir adsorption isotherm and Freundlich adsorption isotherms, indicating adsorption process of removal Cs+ and Sr2+ both have physical adsorption processes and chemical adsorption processes, this is proved that in the adsorption process, adsorption was distributing in the zeolite adsorption points, and it also had intermolecular forces. Adsorption isotherm showed that in simulated seawater, Cs+ and Sr2+ of zeolite adsorption has a strong capacity.4. The adsorption kinetics study shows that: in simulated seawater, zeolite adsorb Cs+ and Sr2+ adsorption process followed pseudo second-order kinetic process, indicating the adsorption rate is influenced by initial concentration of Cs+ and Sr2+, it has a more significant impact, chemical adsorption is the main adsorption control process.5. The thermodynamics of adsorption showed that the adsorption process of delta G is negative, indicating that the adsorption is spontaneous, and delta H is positive, that adsorption process is endothermic, the rise of temperature is favorable to the adsorption process and delta S is positive, show that is process of entropy increase process. |
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