Kinetics of sorption of silver ions on a synthetic NaX zeolite
Abstract
Zeolite based sorbents are used to prevent emissions of iodine and caesium isotopes during the operation of nuclear power plants or as a result of the technological processes of nuclear fuel reprocessing. When working with radionuclides it is important to remember that radiation resistance of zeolites is very high. Thus, with the absorbed dose of up to 1010 rad, the physicochemical properties of a synthetic NaX zeolite do not deteriorate. Zeolite based silver-containing sorbents are used to extract iodine isotopes. The analysis of the existing literature demonstrated that synthetic NaX zeolites can be used to produce such silver-containing sorbents for the extraction of iodine from solutions and gases. However, there are no studies that would describe the kinetic dependences of sorption of silver during the production of the silver-containing sorbent based on synthetic NaX zeolite. This makes it hard to substantiate the mode of production.
The article focuses on the kinetics of sorption of silver ions on a synthetic NaX zeolite. We studied the patterns of the sorption of silver ions on a synthetic NaX zeolite depending on the size of the zeolite grains. All the experiments were carried out under static conditions. Commercial synthetic NaX zeolite was ground and separated into three fractions using test sieves: 0.0250-0.3000 cm; 0.0063-0.0250 cm; 0.0050-0.0063 cm.
The experiments determined the maximum concentration of silver ions in the zeolite, which amounted to 540±10 mg/1 g of the zeolite. The kinetic parameters of the sorption of silver ions on the synthetic NaX zeolite were assessed. We also calculated the diffusion coefficient of the silver ions in the NaX zeolite phase, the rate constant (kinetic coefficient) for the internal diffusion process of the sorption of silver ions by the synthetic NaX zeolite depending on the grain size of the studied zeolite. Mathematical processing of the obtained kinetic curves allows us to state that there is intradiffusion inhibition of mass transfer of silver in the grains of the synthetic NaX zeolite.
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References
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