V. V. Kulemin

Preservation of the charge of radioaerosols formed by condensation of supersaturated 137Cs131I vapor in the course of their bubbling through aqueous solution

Variation of the charge of radioaerosols formed by condensation of supersaturated 137Cs131I vapor, observed when the gas flow passes through an aqueous solution, was studied. The supersaturated 137Cs131I vapor was formed by evaporation of salt crystals from the metal surface heated to high temperatures owing to ohmic resistance. The radioactive aerosols preserve their charge even after bubbling through aqueous solutions, which allows using electric filters for localizing the aerosols.

Sorption of Radioactive Iodine on Polymeric Sorbents from Aqueous Solutions and Gas Phase

Sorption of various species of radioactive iodine from aqueous and gas phases on polymeric sorbents Styrosorb and Polysorb-1 was studied. These sorbents do not take up ionic species of radioactive iodine (131I- and 131IO3-) from aqueous solutions. At the same time, both sorbents take up 131I2 from aqueous solutions at 25°C. At V/m = 500 ml g-1, the distribution factors Kd are ∼1350 and ∼590 ml g-1 with Styrosorb and Polysorb-1, respectively. These sorbents efficiently recover 131I2 from an air flow at 25°C and flow velocity of ∼0.33 cm s-1. The sorption capacity of Styrosorb is approximately four times higher than that of Polysorb-1 and amounts to ∼97.0 mg of I2 per gram of sorbent. These data are consistent with the specific surface areas of the sorbents.

Use of Modified Sorbents Based on Activated Carbon BAU-A for the Extraction of Nonferrous Metals from Aqueous Solutions

The sorption of some nonferrous metals (Cu, Ni, Zn, Pb) from aqueous solutions by granular sorbents based on activated carbon BAU-A has been studied. The surface modification of BAU-A has been conducted by exposing it to a nitrating atmosphere (NOx–air or HNO3 (vapors)–air) at a temperature of 90–110°C for 4 h and impregnating it with 10 wt % of triethanolamine (TEA), tetraethylenediamine (TEDA), or carbamide (CH4N2O). It has been found that modification of BAU-A leads to a decrease in the sorption capacity of this material with respect to Cu2+, Ni2+, and Zn2+ and an increase with respect to Pb2+.

Removal of volatile 137Cs and 131I compounds from an air flow

The removal of volatile 137Cs and 131I compounds from an air flow on various filtering elements was studied. 131I2 and 137CsOH are sorbed on basalt wool, but the degree of their recovery is low: ∼86 and 90–93%, respectively, at the basalt wool bed height of 15–18 cm. The use of a cascade of bubblers in combination with a column packed with basalt wool allows virtually complete (>99.9%) removal of 131I and 137Cs in the form of 131I2, 137Cs131I, and 137CsOH from an air flow.

Behavior of 131I and 137Cs in the oil-water and oil-gas phase systems

The behavior of 131I and 137Cs in various chemical forms in the oil-water and oil-gas phase systems and the sorption of these radionuclides from radioactive transformer oil onto various inorganic and organic sorbents was studied. The degree of the 137Cs extraction depends neither on the time of contact of the oil with aqueous solutions nor on the 137CsI concentration in the solution. Under all the experimental conditions, the degree of extraction of 137Cs did not exceed 5%. The degree of 131I extraction from water by the oil depends on the chemical form of the radionuclide: 131I−, 31IO3−, or 131I2. The maximal extraction (∼70%) is observed for K131IO3, and the minimal (∼25%), for 131I2. Granulated nanocomposites containing particles of carbon or NaX zeolite and Fizkhimin sorbents based on coarsely porous silica gel and containing Ag and Ni in 1: 4 ratio allow efficient removal of 137Cs and 131I from spent transformer oil of GK grade.

Behavior of radioaerosols formed by evaporation of 137Cs131I and 137CsOH from the metal surface in an electrostatic field

The behavior of radioaerosols formed by condensation of supersaturated 137Cs131I and/or 137CsOH vapor in an electrostatic field was studied. Supersaturated 137Cs131I and/or 137CsOH vapor was generated by evaporation of salt crystals from a metal surface heated to high temperatures owing to ohmic resistance. By applying additional potential to the aerosol generator, it is possible to control the behavior of 137Cs131I, 137CsOH, or 137Cs131I + 137CsOH aerosols in an electrostatic field.

Effect of UV radiation on the behavior of CsI radioaerosols in the gas phase

Abstract137Cs131I radioactive aerosols formed upon evaporating CsI from a Pt support to an Ar atmosphere or air under UV irradiation or without it are studied. Without UV radiation, the degree of localization of the aerosols in a bubbler filled with aqueous Na2S2O3 varies from 30% in argon to 60% in air. In sublimation of 137Cs131I from the Pt heater, a considerable amount of nanoparticles is formed, which are not absorbed by the aqueous solution in the bubbler and are even capable of penetrating through a combined filter fabricated from a Petryanov filter and a “White Ribbon” paper filter. In the Ar atmosphere, the conversion of CsI is minimal, being initiated by traces of oxygen and moisture, as demonstrated by data on the Cs/I ratio in various fractions. In both Ar and air, UV radiation increases the localization of the radionuclides in the bubblers, simultaneously decreasing practically by half the amount of 137Cs penetrating across the combined filter. Evidently, this is due to the fact that photoactivation promotes coarsening of nanoparticles through self-agglomeration or interaction with some coarser aggregates. A conclusion is made that UV radiation affects essentially the kinetics of aggregation of the aerosols in the gas phase, but not the rate of the chemical reactions occurring in the gas phase with participation of the aerosols.