RESEARCH INTO DYNAMICS OF ADSORPTION OF HEAVY METALS ON ACID-ACTIVATED BENTONITE

Acid activation of bentonite clay is a common way to obtain porous adsorbents of organic and inorganic substances. Acid activation with preservation of the layered structure is the initial stage of chemical modification. Acid treatment of natural aluminosilicates is aimed at increasing their adsorption capacity and specific surface area. In industrial practice, water treatment of heavy metals is in most cases carried out bypassing the liquid through a fixed layer of backfill. Therefore, in this study, we studied the dynamics of adsorption with the definition of the main characteristics of the process: the speed of the working zone, the coefficient of protective action, the length of the working layer, the loss of protective action time, the duration of the sorption column before leakage. In addition, the establishment of the basic laws of this process can be used to determine the optimal parameters of the sorption material at a given initial characteristic — the length of the layer of the sorption column, the filtration rate. We have studied the possibilities of chemical modification of granular bentonite during acid-salt treatment. Through sorption columns with a height of 0.1; 0.2 and 0.3 m, filled with samples of modified bentonite, were passed model solutions of salts Fe2+, Mn2+, Cu2+ and Cd2+ with a concentration of cations of 0.01 g/dm3. The flow rate of the solution was 0.5; 1.0 and 1.5 m/h. Experimental data show that the optimal sorption values ​​are obtained for samples of modified bentonite: at the same height of the sorbent layer and flow rate, the duration of the layer before skipping in modified samples is 1.25—1.52 times higher than in unmodified ones. It is established that the sorption time before skipping mainly depends on the flow rate and the height of the sorbent layer. Thus, at a layer height of 0.3 m and the same rate of transmission of the solution, the sorption time is up to 3.5 times greater than at a layer height of 0.1 m for all investigated cations.

Efficacy and Safety of a Novel Adsorber for LPS-Selective Hemosorption (Experimental Study)

The purpose of the study is to evaluate the in vitro and ex vivo effectiveness and safety of a new device for extracorporeal blood purification.Materials and methods. The sorption properties and safety of hemoperfusion using the LPS sorption column that employs hypercrosslinked styrene-divinylbenzene copolymer.were studied using three different models:1) Escherichia coli endotoxin solution in aqueous 0.9% NaCl solution with an assessment of the efficacy of endotoxin elimination,2) donor erythrocyte suspension with assessment of the hemoperfusion column safety for blood cells,3) whole donor blood with assessment of hemosorption efficacy and hemoperfusion safety of the new column. Results. There was a 18.5-fold decrease in the endotoxin concentration in 0.9% sodium chloride solution over2 hours of perfusion vs. the baseline, while maintaining the residual sorption capacity of the column. Perfusion of RBC suspension and freshly prepared donor blood through the new LPS column did not demonstrate the emergence and growth of cytolytic markers; on the contrary, a two-fold decrease in the concentration of free hemoglobin containing in the RBC suspension was observed. There was a two-fold decrease in the vitamin B12 concentration, a 3.54-fold decrease in β2-microglobulin and a 2.5-fold decrease in creatinine levels. The atomic force microscopy did not find critical impairment of the morphology of erythrocyte membranes.Conclusion. In vitro and ex vivo tests demonstrated reliable experimental data on the effectiveness and safety of the device that employs a hypercrosslinked styrene-divinylbenzene copolymer for LPS-selective hemosorption, which was not inferior to one of analogues for hemosorption currently employed in clinical practice.

Research on a Gas Index Reflecting the Sorption Process on Carbon Materials in Coal Mines

Based on the concentration of gases such as propylene and ethylene in the atmosphere of a mine, it is possible to assess the development of a mine fire. With the increase of coal temperature, an increased emission of these gases has been observed. However, the experiment results presented in this paper prove that the use of propylene and ethylene for the prediction of the spontaneous combustion of coal have some limitations. It was found that during a flow of gas mixture through the sorption column, propylene and ethylene were sorbed on coal. This phenomenon manifests in smaller amounts of gases at the outlet of the sorption column. By comparing the concentration of ethylene to propylene at the inlet of the column, it was concluded that the ratio was usually below 3, whereas the range of the ratio at the end of the column was between 0.6–353. The value of gases ratio changed depending on the type of coal material in the column. The results of this experiment provide useful information that the quantitative relation between ethylene and propylene concentrations may indicate the occurrence of the sorption process on carbon materials in coal seams.

An X-ray photoelectron spectroscopy study of the products of the interaction of gaseous IrF6 with fine UO2F2

Nuclear fuel reprocessing by fluorination, a dry method of regeneration of spent nuclear fuel, uses UO2F2 for the separation of plutonium from gaseous mixtures. Since plutonium requires special treatment, IrF6 was used as a thermodynamic model of PuF6. The model reaction of the interaction of gaseous IrF6 with fine UO2F2 in the sorption column revealed a change of color of the sorption column contents from pale-yellow to gray and black, indicating the formation of products of such an interaction. The X-ray photoelectron spectroscopy study showed that the interaction of gaseous IrF6 with fine UO2F2 at 125 ?C results in the formation of stable iridium compounds where the iridium oxidation state is close to Ir3+. The dependence of the elemental compositions of the layers in the sorption column on the penetration depth of IrF6 was established.