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.

Design and Properties of Magnetically Controlled Sorbents

In this work, the main parameters and advantages of magnetically controlled sorbents are considered. A large surface of nanodispersed magnetically controlled sorbents adsorbs large amounts of toxins, therefore, the consumption of magnetically controlled sorbents in each operation is insignificant. The ability to quickly replace the spent magnetically controlled sorbents in the detoxification apparatus with a new portion of magnetically controlled sorbents increases the reliability, simplicity and ease of use of the method under consideration. The small thickness of the sorbent layer and the availability of the sorbent surface provide almost instantaneous establishment of equilibrium concentrations, which significantly reduces the required processing time for the biofluid and increases the productivity of the purification process.

Simulation of a Breathing Apparatus on Chemically Bound Oxygen with a Circular Pendulum Circuit of the Air Duct Part

At present, the main prospects for improving the insulating means of respiratory protection are associated with the chemical method of oxygen reservation. The arguments in favor of this choice are the high packing density of oxygen and its self-regulating supply, depending on the physical activity of a person. The main schemes of the air duct part of breathing apparatus on chemically bound oxygen are circular and pendulum. The attempt is made in the article to combine the advantages of the circular (small harmful space) and pendulum (small volume of the dead layer) schemes of breathing apparatus on chemically bound oxygen. For these purposes, the formalism method was developed, which allows mathematically and with the help of a computer to simulate the dynamic sorption activity of the regenerative cartridge of a breathing apparatus with a hybrid (circular-pendulum) scheme of the air duct part. The increase in the protective action of the apparatus is determined due to the use of the resource of the dead sorbent layer in the result of the air flow reverse in the pendulum part of the regenerative cartridge. Feasibility of using a hybrid scheme in the self-rescuers with a short period of protective action is shown. The optimal length of the pendulum part is determined, at which the breathing resistance decreases, and the harmful space occupied by the air returning for inhalation without contact with the unreacted layers of the oxygen-containing product is not increased. Its weak dependence on the total length of the regenerative cartridge and the maximum permissible concentration of carbon dioxide in the air returning to inhalation is shown, which makes the circular pendulum scheme realizable in practice.

ADSORPTION OF ORGANIC DYES ON METALLURGICAL SLAG OF Fe-Ni ALLOY PRODUCTION

The optimal parameters of organic dyes adsorption on the metallurgical slag of the Fe-Ni alloy production of the Pobuzhsky Ferronickel Plant, Ukraine: pH, the mass ratio “dye: slag adsorbent”, the type of chemical activation depending on the mode of the adsorption process were determined. Sorption of organic dyes (methylene blue MB, Congo red and methyl violet MV) by slag was studied spectrophotometrically. It is shown that after acid and alkaline activation the surface adsorption centers are formed on the surface of the slag: hydroxyl and silanol groups, whose dissociation causes a negative charge of the particles surface. The most appropriate ratio is “MB : slag” = 1 mg/g, at which the adsorption value a=0.92 mg/g is recorded at a treatment efficiency of 92 %. The maximum efficiency of MB adsorption by slag based on diopside was recorded in the pH range of 4.8- 10.4. The dependence of the type of chemical activation of slag with basic mineral – diopside on the sorption mode of organic dyes was determined. Slag acid activation is advisable in the static mode of MV sorption; alkaline – under conditions of MV dynamic sorption with a low rate of solution passage through the sorbent layer. Diopside-based slag is expedient to use as an adsorbent of organic dyes at the level of their low concentrations at the local treatment of wastewater generated during the certain technological operations.

THE STUDY OF THE CAROTENOID COMPOSITION OF THE FRUITS OF SEA BUCKTHORN DIFFERENT VARIE-TIES BY THIN LAYER CHROMATOGRAPHY

Sea buckthorn (Hippophae rhamnoides L.) is an object of general interest due to the high content of biologically active substances (BAS). Fruits contain water- and fat-soluble vitamins, organic acids, sugars, tannins, amino acids, flavonoids and carotenoids. The latter, in turn, give the fruits a typical yellow-orange color. Carotenoids (α-, β-, and γ-carotenes) make up 11% of the unsaponifiable fraction of sea buckthorn oil and are very valuable compounds for the cosmetics industry. Leading scientists of the world have found that carotenoids have antioxidant, antimutagenic and antitumor properties, and therefore are actively used for the prevention of cancer. The fruits of sea buckthorn are the raw materials for the pharmacopeia drug - sea buckthorn oil and a large number of various herbal medicines based on it. To separate and identify complex compounds, such as carotenoids, considerable attention is paid to the TLC method. In connection with the foregoing objective of the study was the study of the TLC profile of carotenoids of sea buckthorn fruits of various varieties. Optimal chromatographic conditions were selected that ensure the best separation of carotenoid zones in a thin sorbent layer. In the used eluting system, satisfactory separation of the chromatographic zones of carotenoids is observed, since the value of sorption selectivity is greater than unity. To characterize the chromatographic profile of each variety, it is proposed to use a value of Rs that is more independent of the influence of various parameters and does not require standards. The difference in the obtained TLC profile of carotenoids of sea buckthorn fruits of representatives of ten different varieties, as well as for the fruits of a wild plant, was established. The maximum number of chromatographic zones is observed for the Ryabinovaya variety, and the minimum for the Stolichnaya variety. It was established that by the method of «fingerprints» it is possible to identify the sort of fruits of sea buckthorn by the type of chromatographic profile of carotenoids.

Researching of the concentration distribution of soluble layers when mixed in the weight condition

The analytical and experimental analysis of the processes associated with the formation of structural systems, which includes adsorption, its main paths of formation, patterns of influence on the structure of the environment and its behavior at deformation influences is carried out. The ways of choosing the optimal variant of the adsorption diffusion process for providing the maximum or minimum value of parameters (criterion) are proposed. The physical essence of the relation of the length of the sorbent layer with the time of its protective action (number of bound substance) is considered, which allows to practically characterize the work of the sorbent layer under dynamic conditions. It is noted that the determination of dynamic combined power flow influences during the process of mixing of components plays an important role in the structure formation of the suspension and promotes the construction of calculations for the construction of mixing equipment. The obtained data give an answer a series of questions about the theory of adsorption and diffusion (adsorption actions of van der Walsh forces on surfaces) and the ability to regulate the effect of combined power flows directly affect these process transformations (concentrations). For a illustration and understanding of the general execution of research, depending on the method of applying force, the degree of its previous dispersion and its physical and mechanical properties, a scheme of causal relationships between components and parameters that determine the change in the structure of the components in mixing process on a new discrete machine. The principle of discrete-momentum mixing of components in the weight condition and mechanical influence of the formable working body is considered. Based on the process of mixing the components in the working chamber of the machine, a mathematical model is proposed.

Fuzzy logic approach in the analysis of heat transfer in a porous sorbent bed of the adsorption chiller

Thermal conductivity in the boundary layer of heat exchange surface is the crucial parameter of adsorption process efficiency which occurs in the adsorption bed. In order to improve heat transfer conditions in the adsorption chiller, novel constructions of adsorption beds are currently investigated. The porous structure of the sorbent layer causes low thermal conductivity in the adsorption bed. One of the methods to improve heat transfer conditions is a modification of porous media bed structure with glue which is characterized with higher thermal conductivity. The optimum parameters of sorbents and glues to build the novel coated construction, in terms of improving the chiller Coefficient of Performance (COP) were defined in (Grabowska et al. 2018a). The paper implements fuzzy logic approach for predicting thermal conductivity of modified porous media layers. The developed model allows determination of the sorbent layer thermal conductivity based on various input parameters: arithmetic average of particle distribution d, density ρ and thermal diffusivity k. The data from empirical research was used to build up the model by fuzzy logic methods.

Analysis of heat transfer in a coated bed of an adsorption chiller

Adsorption chillers can be a promising part of sustainable development concept of the global economy due to the utilization of low grade thermal energy sources for cooling production. Therefore, research aiming at improving their performance i.e. Coefficient of Performance (COP) by optimizing the heat and mass transfer condition in the adsorption beds are crucial. Innovative modification of the sorbent layer structure are proposed in the paper in order to improve the heat transfer characteristics in the heat exchanger boundary layer. The analysis of desorption conditions in the parametric model of a coated adsorption bed construction is presented in the paper. The computational fluid dynamics with conjugate heat transfer analysis are used to determine the crucial input parameters for further analytical calculations. The heat transfer condition in novel coated design and a conventional fixed bed are compared in the paper. The developed computational model consisted of three subdomains representing heating water, heat exchanger material (copper) and sorbent (silica gel).