• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.14 no.3
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• pp.223-234
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• 2016

This study aimed to the adsorption-removal of high- radioactive iodide (I) contained in the initially generated high-radioactive seawater waste (HSW), with the use of AgX (Ag-impregnated X zeolite). Adsorption of I by AgX (hereafter denoted as AgX-I adsorption) was increased by increasing the Ag-impregnated concentration in AgX, and its concentration was suitable at about 30 wt%. Because of AgCl precipitation by chloride ions contained in seawater waste, the leaching yields of Ag from AgX (Ag-impregnated concentration : about 30~35 wt%) was less than those in distilled water (< 1 mg/L). AgX-I adsorption was above 99% in the initial iodide concentration ($C_i$) of 0.01~10 mg/L at m/V (ratio of weight of adsorbent to solution volume)=2.5 g/L. This shows that efficient removal of I is possible. AgX-I adsorption was found to be more effective in distilled water than in seawater waste, and the influence of solution temperature was insignificant. Ag-I adsorption was better described by a Freundlich isotherm rather than a Langmuir isotherm. AgX-I adsorption kinetics can be expressed by a pseudo-second order rate equation. The adsorption rate constants ($k_2$) decreased by increasing $C_i$, and conversely increased by increasing the ratio of m/V and the solution temperature. This time, the activation energy of AgX-I adsorption was about 6.3 kJ/mol. This suggests that AgX-I adsorption is dominated by physical adsorption with weaker bonds. The evaluation of thermodynamic parameters (a negative Gibbs free energy and a positive Enthalpy) indicates that AgX-I adsorption is a spontaneous reaction (forward reaction), and an endothermic reaction indicating that higher temperatures are favored.

• Korean Journal of Food Science and Technology
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• v.36 no.2
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• pp.361-364
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• 2004

EPA and DHA extracted from methyl esterified squid oil were purified by silver exchanged resin, silver nitrate-impregnated silica gel, silver exchanged zeolite, and silica gel column chromatography, among which column chromatography using mixture of silver exchanged resin and silica gel (10% by weight) showed the best result. By this simple purification method, EPA and DHA were concentrated from 12.5 to 27.9% (yield, 86,0%) and from 21.7 to 49.5% (yield, 87.3%), respectively. Silver exchanged resin had additional advantages of outstanding reusability and simple recovery of silver.