The Effect of Hydrophobization of Ag-Containing Zeolites on Absorption of CH3131I from the Water Vapor-Air Phase

The effect of hydrophobization of Ag-containing nonmodified and acetylene-modified zeolites with poly(vinyl chloride) (PVC) on sorption characteristics of sorbents with respect to CH₃ ¹³¹I was studied. The PVC coating on the sorbent results in increased absorbtion of CH₃ ¹³¹I from a water vapor-air flow at a humidity of up to approximately 70 vol %; the decontamination factor of approximately 10⁵ is reached. The sorbent modified with PVC retains radioiodine at heating to 300°C and can be proposed for practical purposes.     

Mechanism of the modifying effect of neuraminidase of the influenza virus on the development of Rauscher leukemia

It was established that neuraminidase--an immunosuppressive component of influenza virus--stimulated Rauscher leukemia in BALB/c mice. This effect is connected with earlier manifestation of sensitization to embryonic antigens and the appearance of immature PNL+ cells in spleens of infected mice rather than with immunosuppression. The mechanism of cocarcinogenic effect of viral neuraminidase is discussed.     

Sorption of CH3131I from the Gas Phase on Modified Metal-Substituted Zeolites Containing Copper and Silver Ions

Sorption of CH₃ ¹³¹I from vapor-gas flow with acetylene-modified Cu⁺- or Ag⁺-containing zeolites in argon atmosphere was studied. The decontamination factor of the gas flow from radioiodine with the sorbent containing 7% of Ag⁺ is considerably higher than that of the Cu⁺-containing zeolite and reaches more than 10⁴ at the bed height of 6.5 cm and contact time of 3.4 s. The sorbent capacity is more than 9 mg of CH₃I per 1 g of the sorbent. In treatment of the sorbent with water after absorption of CH₃I, ¹³¹I is not noticeably desorbed to aqueous phase.     

Sorption of cesium iodide radioactive aerosols on metal felt during oxidative hydrolysis in steam gas-system

The behavior of ¹³⁷Cs ¹³¹I radioactive aerosols at sorption in a column packed with Bekipor WB metal felt from argon, air, and steam-gas flow was studied to assess the possibility of formation of CsI CsOH and CsI₃ in the course of CsI oxidative hydrolysis. The layer distribution of radionuclides in the column was analyzed as influenced by temperature (405–560 K), carrier gas humidity (up to 60 vol %), flow velocity (2–6 cm s¹), and amount of cesium iodide sorbed on the felt (0.7–65.0 mg). It was found that the oxidative hydrolysis under certain conditions yields CsI CsOH and CsI₃ aerosols. Although under the experimental conditions studied the sorption of radionuclides on the metal felt is nearly quantitative (97–99%), escape of the radionuclides from the column upon prolonged passing of steam-gas mixtures cannot be excluded.Translated from Radiokhimiya, Vol. 46, No. 5, 2004, pp. 449–453.Original Russian Text Copyright © 2004 by Kulyukhin, Mikheev, Kamenskaya, Rumer, Konovalova, Novichenko.     

Metal-Containing Zeolites as Sorbents for Localization of Radioiodine and CsI Aerosols from Vapor-Air and Aqueous Phases

New sorbents for efficient sorption of radioiodine and radiocesium from the vapor-gas phase and aqueous solutions were prepared by treatment of Cu⁺- and Ag⁺-substituted NaX and NaA zeolites with acetylene in aqueous solution. The distribution factor K _d of radioiodine and radiocesium between the modified sorbents and aqueous solutions is higher than 10³-10⁴ ml g^{- 1}. Decontamination factor of the vapor-gas phase with respect to radioiodine and ¹³⁷CsI aerosols exceeds 10²-10³ and 10³, respectively. The sorption properties of the modified sorbents in both aqueous solutions and the vapor-gas phase are better than those of the initial sorbents. However, localization of radioiodine from the vapor-gas phase with the Cu⁺-containing sorbents is less efficient than with the Ag⁺-containing zeolites. At the same time, in aqueous solutions the sorption capacity of the Cu⁺-containing sorbents for radioiodine is appreciably higher than that of the Ag⁺-containing sorbents. The sorption properties of the modified sorbents were studied as influenced by various factors. Paracomplexes of univalent copper and silver with C₂H₂, H₂O, and anions present in the solution are probably formed during modification of the metal-containing zeolites. The dependence of K _d of radioiodine on the metal concentration in the sorbent, the free pore volume of the sorbent, and the anion nature was revealed.     

Cocrystallization of Radioiodine Compounds from the Gas Phase

The study of the behavior of ¹³⁷Cs¹³¹I in the presence of MCl (M = NH₄ ⁺, K⁺, Ag⁺, and Cu⁺) in the water vapor-gas phase showed that CsI aerosols are localized in the MCl matrix owing to both agglomeration cocrystallization [¹³⁷Cs¹³¹I-MCl systems (M = K⁺, Ag⁺, NH₄ ⁺)] and agglomeration capture [¹³⁷Cs¹³¹I-CuCl system]. The main advantage of the first process is formation of crystalline globules encapsulating radioiodine in their bulk, which prevents transformation of radioiodine into elemental iodine and methyl iodide.