Sorption of Radioactive Iodine and Fluoride Ion on Hydroxyapatite from the Aqueous Phase

Sorption of the ¹³¹I^-, ¹³¹IO₃ ^-, and F^- ions on various samples of hydroxyapatite (HAP) from aqueous solutions was studied. The HAP samples were prepared by the following reactions: Ca(OH)₂ + H₃PO₄ HAP, CACl₂ + Na₃PO₄ + NaOH HAP, and Ca(NO₃)₂ + HAP seed + (NH₄)₂HPO₄ + NH₃ HAP. None of the HAP samples sorb ionic species of radioactive iodine from aqueous solutions. As for F^-, the best sorption properties are exhibited by the HAP sample prepared by the second reaction. The degree of recovery of fluoride ion with the HAP precipitate in 5 min, 4 h, and 5 days of the contact of the solid and liquid phases is 54, 66, and >95% of the initial F^- amount, respectively. The distribution factor K _d of the fluoride ion between the HAP solid phase and solution decreases with increasing V/m ratio and pH of the initial solution.     

Absorption of Nitrous Oxide from Air by Aqueous and Organic Solutions

Theoretical Foundations of Chemical Engineering - Findings from a study of the N2O absorption from an air flow in various aqueous and organic solutions at 293–298 K were reported. The maximum...     

Removal of Suspended Solids and Petroleum Products from Aqueous Media

Theoretical Foundations of Chemical Engineering - Helical filter elements and a fibrous material based on basalt wool have been studied as potential filtering materials for removing solid...     

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

Theoretical Foundations of Chemical Engineering - The sorption of some nonferrous metals (Cu, Ni, Zn, Pb) from aqueous solutions by granular sorbents based on activated carbon BAU-A has been...     

Simulation and measurements of EBIC images of photoconductive elements based on HgCdTe

EBIC investigations of HgCdTe-based photoconductive elements have been carried out. Simulation of the two-dimensional distribution of the EBIC signal is carried out by numerical solution of the drift-diffusion ambipolar equation. It is shown that fitting the measured EBIC profiles by simulated ones allows us to obtain the effective diffusion length in the element and the surface recombination velocity on its lateral sides. The regions with enhanced recombination rate are reveled in the elements degraded by prolonged annealing at 60°C. The lateral resolution in the EBIC measurements on photoconductive elements is estimated. The text was submitted by the authors in English.     

Oxidative Hydrolysis of CsI Radioaerosols in a Steam-Gas Medium: A Study Using Filtration Elements

Oxidative hydrolysis of ¹³⁷Cs- and ¹³¹I-labeled CsI aerosols in a steam-gas medium was studied at their localization on a column with filtration elements. At the air stream temperature of 403–423 K, water vapor content in air from 3–4 to 90 vol %, and stream velocity in the sorption column of 6–24 cm s^?1, the CsI aerosols undergo oxidative hydrolysis, and the hydrolysis products react with the surfaces of the metallic and paper filtration elements. By varying the filter material, its internal surface area, and experimental conditions, it is possible to localize on the filtration elements from ～5 to 98% of 0.17–70 mg of CsI coming to the filtration system.     

Evolution of Models and Algorithms for Calculating the Parameters of Technological Processes to Obtain Materials for Micro- and Nanoelectronics

The results of creating a system of models and algorithms for calculating the parameters of technological processes for obtaining materials of micro- and nanoelectronics and designing equipment are considered. It is shown that the distinctive feature of the teaching methods for special technological courses in electronic engineering materials is the construction of courses by analogy with the technological processes for obtaining materials for electronics: from a bulk single crystal to instrumental structures, whose dimensions do not currently exceed several tens of nanometers. A scientific model approach to the solution of technological problems was formed in the study of heat and mass transfer processes, which together with the processes of interaction in liquids and gas, taking heterogeneous reactions into account, are the theoretical basis of the technology of electronic engineering materials. The possibilities of physical and mathematical modeling are compared. Approaches to create mathematical models of the growth processes of single crystals of semiconductors, epitaxial layers, and heterostructures are considered and the possibilities of their practical use are determined. It is determined that the ideas proposed by V.V. Krapukhin at the initial stages of training specialists in the field of the technology of electronic material and developed by his students identified the possibility of training several generations of qualified specialists.     

Localization of cesium radioaerosols on granulated materials from the water vapor-air medium

The paper deals with localization of ¹³⁷Cs¹³¹I radioaerosols and products of their oxidative hydrolysis from the water vapor-air medium with various filtering elements: granulated sorbents based on silica gel and their combination with a helical filtering element (HFE) and TRUMEM metallic membrane filter (pore size ～2.0 μm). The degree of localization of ¹³⁷Cs¹³¹I aerosols was studied in relation to the air flow temperature, water vapor content, linear flow velocity in the sorption column, and amount of ¹³⁷Cs¹³¹I aerosols delivered to the filtration system. Localization of ¹³⁷Cs₂MoO₄ radioaerosols on the granulated sorbents was also studied.