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Purpose. Investigation of the adsorption activity of nanoporous carbon materials (NCMs) prepared by alkali activation with thermal shock. Methodology. The porosity characteristics of NCMs were calculated according to isotherms of lowtemperature (77 K) adsorption and desorption of nitrogen (2D-NLDFT-HS method). Adsorption measurements were performed at 25°С and a constant content of NCM (1 g/l) in aqueous solutions. Adsorption kinetics data were calculated by the 1st and 2nd order models and intraparticle diffusion. Adsorption isotherms are approximated by Langmuir and Freundlich models. Findings. It were studied the adsorption kinetics of phenol (Ph), 4-chlorophenol (CPh), methylene blue (MB) and lead cations by NCMs formed from brown coal (NCM(B)) and long-flame coal (NCM(D)) in a new process - alkaline activation with thermal shock. Kinetic data were obtained at the same initial concentration of adsorbates (5.0 mmol/l). The adsorption equilibrium was found to achieve for 2-4 hours depending on the adsorbate. The kinetics of adsorption obeys the second-order equation, and the maximum adsorption capacities increase in the series Pb(II) < MB < Ф < ХФ and are in the range of 0.736-3.350 mmol/g for NCM(B) and 1.097-4.359 mmol/g g for NCM(D). The adsorption rate is limited by the interaction of molecules with surface adsorption centers, and not by diffusion into the NCM nanoporous structure. The initial adsorption rate is highest for the adsorption of CPh (1.672 and 2.050 mmol/g•min), the lowest for the adsorption of MB (0.062 and 0.075 mmol/g•min). During the first minute, about half of the maximum amount of CPh is adsorbed. Adsorption isotherms were found to be approximated by the Langmuir (R2 = 0.981-0.994) and Freundlich (R2 = 0.986-0.998) models with a close errors. The capacities of saturated layers of adsorbates calculated from the Langmuir model increase in the same order as the maximum adsorption capacities. The Freundlich model, which assumes a chemically inhomogeneous adsorbent surface, is better applicable. This is probably a consequence of the fact that the chemical structure of NCM adsorption centers is more diverse due to the «explosive» formation of volatile products during thermal shock. A comparison of the adsorption parameters of the obtained NCMs with literature data allows us to evaluate the synthesized materials as effective adsorbents for purifying aqueous media from pollutants and toxic compounds. Originality. For the first time, the adsorption of phenol, 4-chlorophenol, methylene blue dye and lead cations by NCMs samples formed from brown and long-flame coals under alkaline activation with thermal shock. Practical value. The obtained results make it possible to evaluate the practical prospects of NCMs as adsorption materials for the purification of aquatic environments from ecotoxicants. [ABSTRACT FROM AUTHOR]

The present work concentrates on synthesizing and adsorption surface investigation of polytetrazole polymer (P-T) created from polyimine (P-S) grafted with sulfadiazine drug. The prepared polymer is synthesized by mechanochemical polycondensation reaction between dialdehyde aromatic compound and diamine aromatic compound by applying appropriate polar solvent and glacial acetic acid at (78 °C) as dependent on the polymerization reaction. The synthetic route to prepare tetrazole polymer (P-T) consists off multi chemical reaction process, firstly the synthesis of polyimine backbone (P-S) (4-(((4'-amino-3,3'-dimethyl-[1,1'-biphenyl]-4- yl)imino)methyl)benzaldehyde) by Schiff base reaction between monomers diamine (o-tolidine) and dialdehyde (terephthalaldehyde). Secondly, is the sulfadiazine azid formation, since the conversion of sulfadiazine drug to sulfadiazine azid (4-azido-N-(pyrimidin-2-yl)benzenesulfonamide) occurred by diazonium salt formation of sulfadiazine at very low temperature (0–5 °C) and then reaction with sodium azide (NaN3) under cool conditions to convert amine group (NH2) to azide group (N3), after that sulfadiazine azide was grafted onto the polyimine backbone (P-S) by cyclization reaction process to form polytetrazole (P-T). All prepared products: sulfadiazine azide, polyimine (P-S) and polytetrazole (P-T) were characterized by FT-IR spectroscopy. Finally, the adsorption surface investigations of the prepared polymers (P-S) and (P-T) were studied for adsorption of Brilliant cresyl blue (BCB) dye. All adsorption results were recorded by using an UV-Vis spectrophotometer. Since the polytetrazole (P-T) gave very good adsorption results when applied to (BCB) dye adsorption, there can be suggestion on the polytertazole polymer applicability in many various environmental and medical applications. [ABSTRACT FROM AUTHOR]

There are more materials being utilized as industry develops, and these materials are frequently exposed to severe corrosion while being employed. This depends on the material/corrosive pair and the environment in which these two elements come together; among the finest methods is the application of inhibitors to ensure their protection in contact with aggressive environments such as hydrochloric acid. This work describes the study of the corrosion behavior of a Nickel-Phosphorus coating in an acidic 1M HCl medium and the evaluation of the protective power of an organic compound. The Ni-P alloys were obtained by the electrodeposition technique from a solution containing Nickel Sulfate and Sodium Hypophosphite (NaH2PO2) on a steel substrate. The effect of drug Solfarlem as a corrosion inhibitor of Nickel-Phosphorus alloy in 1 M HCl was studied using electrochemical impedance spectroscopy, polarization curve and weight loss methods. Results show that the inhibition efficiency of this inhibitor by all methods was in good agreement and the optimal efficiency with a concentration of 6.10 – 5 mol/L was about 96%. The values for free energy of adsorption ΔGads, were calculated at each surface coverage, of the studied compound by applying the mathematical model. The adsorption of the inhibitor molecules corresponds to the Langmuir adsorption isotherm, followed by chemical adsorption on the surface of the Nickel-Phosphorus alloy. [ABSTRACT FROM AUTHOR]

The contact wetting is one of the effective methods of studying the adsorption capacity of sorbents. The purpose of the work was to compare the experimentally obtained data on the adsorption capacity of shungite, obtained by the sessile drop method, and the results of modeling the behavior of liquid droplets on heterogeneous surfaces using the Boltzmann lattice method, and to show the suitability of the simplified version of the LBM method that we applied within the framework of a two-dimensional model for modeling complex cases of contact interaction between liquids and sorbent, when it cannot be carried out by the method of contact wetting. The adsorption properties of shungite with regard to the extraction of various impurities from water-alcohol solutions and the capability of the sorbent to recover were investigated by the method of contact wetting and analyzed by involving the data obtained by the methods of nitrogen adsorption, thermogravimetry and IR spectroscopy. It is shown that the adsorption properties of shungite are due to the presence on its surface of hydroxyl functional groups attached to carbon atoms in phenol or enol form, which give the surface hydrophilic characteristics. These groups play a key role in the adsorption of components from the liquid (aqueous) phase due to the formation of a hydrogen bond during the sorption of components from the liquid phase, and are restored after heating in the temperature range of 80–180 °C with the formation of carbon-containing gases and water. It has been found that silanol groups present in shungite do not participate in sorption. Compared to the original shungite sample, the sample after five cycles of adsorption is characterized by a noticeable effect of mass loss (1.8 %) in the temperature range of 80–180 °С. At the same time, the loss of mass is not significant at temperatures below 100°С. This suggests that the sorbed substances are in the pores and not on the surface of shungite, and they begin to be removed only after heating above 100°C. The LBM method was used to study fast-moving processes at the meso-level. A comparative analysis of the experimental data obtained by the method of contact wetting with the results of simulation by the Boltzmann lattice method within the framework of the two-dimensional model was carried out. 2D modeling by the LBM method turned out to be an effective means of studying capillary condensation in mesopores, anticipatory wetting of the solid phase, liquid penetration into a porous medium with different topologies, and the formation of anisotropic droplets and anisotropic bridges. The role of mesopores in the sorption process was analyzed by modeling the behavior of liquid droplets on heterogeneous surfaces and using data on the course of adsorption and capillary processes on the surface of a solid phase with different levels of porosity, roughness, and functional composition. [ABSTRACT FROM AUTHOR]

An important environmental problem is the removal of contaminants and the purification of domestic and industrial water from pollutants of various nature. There is a separate issue of cleaning the effluents of pharmaceutical enterprises. Various chemical and physical methods are used to solve these problems, such as settling, coagulation, filtration, and sorption techniques. Adsorption with using efficient and reusable adsorbents is the most effective and cheap. In recent years special attention has been paid to the use of sorption materials based on hydrolysis lignin, which has a high sorption activity in relation to ions of some heavy metals, dyes, organic compounds and pharmaceuticals. The use of lignin as an adsorbent simultaneously solves two problems: the disposal of paper production waste and the purification of sewage from various types of pollutants. The aim of this work was to study the sorption properties of hydroylysis lignin in aqueous solution in relation to some medical substances of different chemical nature, existing in solution in cationic, anionic or neutral forms. The point of zero charge of hydrolysis lignin was determined, which is equal to рНPZC = 4.95. The adsorption of rivanol, proflavin, doxorubicin, levofloxacin, furacilin, and salicylic acid by hydrolysis lignin was studied as dependence on the pH of the solutions and the concentration of adsorbates. It was found that adsorption largely depends on the structure of the pharmaceuticals and the pH values of the solutions. It is shown that the studied medical compounds, which exist in the solution in the form of cations, are adsorbed the best (rivanol, proflavin, doxorubicin). Adsorption of these substances occurs mainly due to electrostatic interaction with negatively charged surface groups. Adsorption of anionic form (salicylic acid) is the smallest and is observed only at quite low pH values. Levofloxacin is adsorbed mainly in the form of zwitter ions, and furacilin is in neutral form. The adsorption of these both compounds occupies an intermediate value of adsorption amount. The obtained adsorption isotherms are well lined up in Langmuir coordinates. Quantitative parameters of adsorption values - of maximum adsorption and equilibrium constants were calculated. Quite high values of these parameters indicate that hydrolysis lignin can be used as an adsorbent for the removal of these pharmaceuticals. [ABSTRACT FROM AUTHOR]

The use of hydrophobic silicas as medical adsorbents in comparison with hydroxyl silicas allows to increase the adsorption of some toxins on their surface due to the reduction of water adsorption. The purpose of this study was to find a co-adsorbate that, adsorbed on a hydrophobic surface, would allow the preparation of aqueous suspensions of an enterosorbent based on methylsilica, and, once inside the body, would be easily destroyed by the enzymes of the gastrointestinal tract, freeing its surface for the adsorption of toxins on it. The structure of the hydrate shell and the adsorption capacity of composite materials based on methyl silica and gelatin obtained by different methods were investigated by a set of physical and chemical methods. Low-temperature ¹ H NMR-spectroscopy has been used to study of water clusters bound to composite surface. It has been found that the water in the composite on the basis of hydrophobic methyl silica and gelatin gel is present in the form of clusters with a radius of 0.5–15 nm and is in a strongly associated state when measured in air. When a liquid hydrophobic medium is added, the water partially passes into a weakly associated state. The bound water reacts to the presence of chloroform by changing the radial distribution of the adsorbed water clusters. It has been shown that for the composite system methyl silica AM-1/gelatin (5/1), the introduction of chloroform into the interfacial space leads to a significant decrease in the interfacial energy, which indicates a partial displacement of water by the hydrophobic solvent at the interface. At the same time, for composites made on the basis of dry powders, this effect is not observed and its interfacial energy has an intermediate value between the interfacial energies of methyl silica and gelatin containing the same amount of water. Adsorption of Congo red as the medium molecular weight toxins marker from aqueous solutions on the studied composites was studied in comparison with methylsilica. It has been found that gelatin in the composition of composites contributes to increasing dye adsorption. The amount of adsorbed Congo red depends on the method of preparation of the composite and the ratio of silica to gelatin. It is concluded that AM-1/gelatin composite systems can serve as effective adsorbents for removing medium molecular weight molecules from aqueous solutions. [ABSTRACT FROM AUTHOR]

Blood loss is one of the main causes of death, especially in war and natural disasters. At the beginning of the fullscale Russian-Ukrainian war we established the laboratory and later the industrial production of a powdered topical hemostatic composition based on nanosilica which is intended for providing first pre-medical aid. The composition contains nanosized silica A-300 and sodium alginate as two active ingredients in a mass ratio of 4:1. The aim of the work was to develop the optimal technological process for the production of a hemostatic composition and carry out physicochemical and medical-biological studies of semi-finished products and the final product. Bulk density measurements, optical microscopy, IR spectroscopy method and microbiological research were used to study the initial materials, intermediate products as well as the final product. The effectiveness of the hemostatic effect of the composition was checked on the model of parenchymal bleeding from the liver of a rat, using the time to stop bleeding (min) as a criterion. As a result of the research, a two-stage method of manufacturing the composition is proposed: at the first stage, certain parts of the initial materials are treated in a ball mill, obtaining the semi-finished product "A-300/sodium alginate"; at the second stage, this semi-finished product is mixed with nanosilica and sodium alginate, obtaining the final product. It is shown that the bulk density serves as a useful technological parameter to control of which helps to produce a structurally homogeneous final product. In the IR spectra of the semi-finished product and the finished product, only the absorption bands of silica and sodium alginate are observed, that is, foreign substances are not formed during technological process. The microbiological purity of the composition meets the pharmacopoeial requirements for drugs of this category. An experimental study of the topical hemostatic effect of the composition revealed its significant advantage compared to the inorganic hemostatic substance kaolin, which acts according to a similar adsorption mechanism. [ABSTRACT FROM AUTHOR]

The paper describes a simple analytical model that allows the calculation of hydrogen surface coverage under the influence of several processes that can co-occur during the ion-beam bombardment/sputter analysis of a sample surface, in particular during analysis by secondary ion mass spectrometry (SIMS). The model considers processes of dissociative adsorption, desorption, absorption from the surface into the sample volume, and removal by ion bombardment. After describing the model, we provide some examples of its practical applications for interpretation of the experimental results obtained during in situ SIMS studies of hydrogen interaction with the hydrogen-storage alloys TiFe, Zr2Fe, and with nickel. In the examples, some quantitative characteristics of surface-related processes involving hydrogen, such as hydrogen sputtering rate, activation energy of hydrogen desorption and absorption, have been successfully determined using various model approaches. [ABSTRACT FROM AUTHOR]

The adsorption of the C60 fullerene molecule has been studied in various configurations on a reconstructed Si(100) silicon surface. Among fullerenes, fullerene C60 is of particular importance, since it has the most stable form and consists of 60 carbon atoms. Monocrystalline silicon has the diamond structure, the size of its crystal lattice is 5.43 Å. The MD-simulation calculations have been performed using the open source LAMMPS MD-simulator software package and the Nanotube Modeler computer program. The Tersoff interatomic potential has been used to determine the interactions between the Si-Si, C-C and Si-C atoms. The adsorption energy of the C60 molecule on the reconstructed Si(100) surface, the bond lengths and the number of bonds formed depend on the adsorption geometry, i.e. at what point on the substrate the molecule is adsorbed and in what configuration. [ABSTRACT FROM AUTHOR]

The paper studies how a corrosion inhibitor made of vegetable waste from food production - pomegranate peel - is adsorbed on the surface of aluminum. The mechanism of inhibitor action is largely driven by the fact that the active substances are chemisorbed on the metal surface and form a film that isolates this surface from the aggressive influence of the environment. [ABSTRACT FROM AUTHOR]

The conducted research established the porous structure of the materials through lowtemperature nitrogen adsorption. It was demonstrated that the nitrogen sorption isotherms for the investigated samples belong to Type IV with H4 hysteresis associated with bottlelike pores. The specific surface area of the granulated composite samples was determined, ranging from 99 to 111 m2/g. Additionally, it was shown that an increase in iron content in the samples leads to a reduction in micropore content. Active centers on the material's surface, primarily composed of hydroxyl groups, were investigated using infrared spectroscopy. The kinetics of chromium (VI) adsorption were explored, and it was established that the iron-to-zirconium ratio in the reinforcement solutions hardly affects the duration of establishing adsorption equilibrium, which is approximately 60 minutes. Pseudo-first-order and pseudo-second-order models were applied to describe the kinetics of the adsorption process. The dependence of the chromium (VI) removal efficiency on the solution pH was determined. It was demonstrated that the synthesized samples exhibited high adsorption in acidic conditions with a sharp decline when transitioning to neutral and alkaline environments. It was shown that the maximum sorption capacities of the synthesized granulated composite samples significantly depend on the ratio of iron and zirconium ions. One of the most efficient samples is that with 50% Fe and 50% Zr, exhibiting a maximum sorption capacity of 13.29 μmol/g at pH 6. The use of Langmuir and Freundlich models allowed establishing the fundamental adsorption properties of the materials. [ABSTRACT FROM AUTHOR]

The purpose of the work was to evaluate the adsorption capacities of carbon materials (CMs) from long-flame coal with respect to 4-chlorophenol (CPh) and the influence of CMs preparation temperature under alkali activation at a low KOH/coal ratio (1 g/g). The CMs were obtained by heating coal with KOH to specific temperatures ranging from 350 to 825°C with a 1-hour holding time. Specific surfaces of all pores (SDFT), micropores (Smi), ultramicropores (Sumi), and supermicropores (Ssmi) were determined using nitrogen adsorption-desorption isotherms. The kinetics and isotherms of CPh adsorption as well as the maximum capacities (ACPh(m))were measured at 25°C. Temperature was found to be a key factor in the formation of CMs nanoporosity and their ability to adsorb CPh. As the temperature increases, the SDFT, Smi, and Ssmi values increase monotonically, while Sumi exhibits an extreme change with a peak at 600°C. The adsorption kinetics followed the secondorder model, reaching equilibrium within 2 hours. About half of CPh was absorbed in the first minute. The rate-determining step was identified as the interaction of CPh with the adsorption centers. The adsorption isotherms were best described by the Langmuir model. The ACPh(m) capacity was found to increase with temperature from 32.3 mg/g to 486 mg/g, a 15-fold increase, corresponding to an SDFT increase by 138 times. The ACPh(m) values exhibited an S-shaped dependence on SDFT, Smi, and Ssmi, indicating the non-uniform formation of adsorption centers with surface development. This was attributed to the molecular structure reorganization of CMs, which is also influenced by the activation temperature. [ABSTRACT FROM AUTHOR]

The possibility of obtaining ecosorbents based on biologically and chemically modified carbon material from vegetable raw materials for the removal of Cd (II), Cu (II), Pb (II) and Zn (II) ions from aqueous solutions was studied. The peculiarities of obtaining an ecosorbent from sugar cane bagasse and rice husk are substantiated. Sulfur - containing biocarbon ecosorbent is obtained by one-stage pyrolysis of raw materials together with sulfur-containing reagents at a temperature of 350-400 °C. The temperature parameters and the duration of the pyrolysis process were determined experimentally from the conditions of the maximum content of biochar in the pyrolyz ate. Sulfurcontaining biochar has a high absorption capacity for heavy metal ions (more than 80-90 %) compared to the original biochar. Its specificity is due to the formation of insoluble metal sulfides on the surface and in the pores of the sorbent. Microbiological modification leads to the creation of biosorption material for strong binding of heavy metal ions. Sulfate-reducing bacteria immobilized on the surface of biochar are also able to convert sorbed heavy metals into insoluble sulfide forms. A comprehensive study of the structural-porous and sorption properties of the original and modified biochar was conducted. It was established that chemical and microbiological modification of biochar increases its sorption capacity due to the improvement of structural-porous and ion-exchange properties of the material. But the key property of ecosorbents from pyrolyzed and modified vegetable raw materials is the ability to form insoluble sulfide forms of metals on the surface and in the pores of the ecosorbent. [ABSTRACT FROM AUTHOR]

Purpose. A leading cause of water contamination is the widespread use of dyes, which are consumed in large amounts. The purpose of the present study was to investigate the potential of the Cactus paddle (CP) as an environmentally safe biosorbent for removing Basic Red 46 dye from aqueous media. Methodology. Various analytical tools, comprising XRF, XRD, BET/BJH, FTIR, and pHPZC methods, were used to examine the surface characteristics of the biosorbent. For assessing the ability of CP for BR46 adsorption, batch adsorption assays were performed. Findings. An amount of 3.45 mg ∙ g-1 of BR46 was adsorbed at pH 7, 500 rpm and 293 K within 180 minutes. The isothermal data was described by both the Freundlich and the Langmuir equations with R² ≥ 0.984 and χ² ≤ 0.01. The kinetics was well described by a PSO model, suggesting that physico-chemical interactions govern the adsorption process. Originality. For the first time, the effective use of a local raw material resource CP as a biosorbent for the removal of BR46 dye has been substantiated. Practical value. As a result of the findings of this study, it seems possible that CP can be regarded as a sustainable resource, which would create a possibility for addressing environmental concerns in the future. [ABSTRACT FROM AUTHOR]

Atmospheric air pollution is determined by the functioning of both technogenic and natural sources of pollution. The main anthropogenic sources of pollution are: transport, industrial enterprises, energy facilities and agriculture. In order to select a rational and effective method of atmospheric emissions purification from harmful components, systematic study was carried out to identify the potential of natural zeolites of Georgia. In particular, four samples of zeolite-containing rocks were investigated: analcime, clinoptilolite, phillipsite, mordenite and their modified forms. By means of the chromatographic method of researching the adsorption properties of natural zeolites, the best adsorption capability of mordenite and its modified hydrogen form obtained by two methods towards nitrogen oxides has been revealed. The perspective and profitability of using the hydrogen form of mordenite treated with ammonium in the processes of purification of nitrous gases from exhaust gases is shown, as well as the possibility of using the recovered products (aqueous solutions of ammonium salts) obtained from its regeneration as a nitrogen fertilizer in agriculture. The experimental adsorption purification of the sample (H-mordenite) was carried out in the process of research. The sample was taken from the outlet pipe of the contact apparatus in the ammonia oxidation shop of the nitric acid production enterprise of LLC “Rustavi Azoti”. It has been found that the modified mordenites can be proposed as an environmentally friendly, highly efficient sorbent in the processes of air purification from toxic impurities. Of the two forms of H-mordenite investigated, the adsorption data obtained for NH4+-ion-modified mordenite is approximately 20 % better than the acid-modified form. It should be noted that the use of granulated zeolites (mordenite) in adsorbers with dense packing is very effective. It is also important from the economic point of view that it is possible to reuse spent high-silica sorbents after their regeneration by oxidation method, since such zeolites are resistant to oxidants, such as hydroxyl radicals, ozone, etc., and it is possible to regenerate them without removing them from adsorber. [ABSTRACT FROM AUTHOR]

Purpose. To remove of basic textile dye Azucryl Red (AR) from aqueous solutions using hyper-aluminous kaolins from Charente deposits (France) in natural and calcined states. Methodology. Batch interactive parameter pH, pHpzc contact time, dye concentration, adsorbent loading and temperature are taken to obtain optimums for the AR adsorption process in natural and calcined kaolin named respectively Kca, Kcm, Ckca, and Ckcm. Findings. The adsorption equilibrium was established in 7 min while the second-order kinetic model better described the adsorption kinetics for all kaolins with the chemisorption process. The adsorption isotherm of the results obtained corresponds better to the Langmuir model. The maximum quantity retained was 67.97 and 73.38 mg/g respectively for Kcm and Kca samples. Moreover, in the calcined state, the maximum quantity retained was 76.66 and 75.64 mg/g respectively for the calcined kaolin CKcm and CKca samples for a temperature of 298 K and pH = 6. The thermodynamic nature of the adsorption process was determined by calculating ΔH, ΔS and ΔG° values. The positive value of ΔH° confirms the fact that adsorption is endothermic spontaneous which is enhanced at higher temperatures. Originality. The heat treatments of the different kaolins at 400 °C enhance the adsorption process. Therefore, the results indicate that . qCkcme / qkcme / qCkcae /qkcae / qCkcme performed with the highest adsorption capacity in the removal of the dye, followed by Ckca. Practical value. Adsorption processes of toxic Azucryl Red dye in the aqueous medium using natural and calcined hyper-aluminous kaolins at 400 °C were investigated. Optimization and modeling of the adsorption parameters with the theories by Langmuir, Freundlich and Elovich allowed us to find the optimal experimental conditions for sorption. Our results therefore indicate that the adsorption process of Azucryl red dye from aqueous solutions was enhanced when calcined kaolin at 400 °C containing organic matters was used. [ABSTRACT FROM AUTHOR]

In this work, a comprehensive comparative study of adsorbents obtained by combining coconut coal with coagulants based on aluminium salts (Al2(SO4)3 and AlCl3) and flocculants (sodium alginate and chitosan) was obtained and carried out for the removal of iron and manganese ions from model solutions. Adsorbents based on coconut coal and flocculants were obtained by the impregnation method followed by drying at a temperature of 50 °C for 6 hours (КАУ+Х1, КАУ+Х2 and КАУ+АН). Adsorbents based on coconut coal and coagulants were produced by adding aluminum salts to an aqueous solution of urea at a temperature of 95 °C with intensive stirring for 30 minutes using coconut coal (КАУ+ AlC КАУ+AlS). The adsorbents were tested for their ability to remove iron and manganese ions from water systems. The comparative characteristics were based on the results of the adsorption kinetics study. It was found that the most effective adsorbent for removing iron and manganese ions is based on coconut coal and sodium alginate flocculant (КАУ+АН), in comparison with coconut coal alone. The recommended contact duration for the adsorbent and adsorbate is 60 minutes. This duration achieves an effective degree of purification for ferric ions (82.5 %) and manganese ions (84.65 %). Compared to КАУ coconut coal and other studied adsorbents, the purification rates for iron ions and manganese ions are 7-15 % and 18-20 % higher, respectively. The study determined that the optimal dose of КАУ+АН adsorbent is 5 g/dm3. The advantages of this adsorbent, which is characterized by a high degree of extraction of iron and manganese ions in static conditions and can be recommended for cleaning aqueous solutions and further research in dynamic conditions, are given. [ABSTRACT FROM AUTHOR]

The conditions and characteristics for nanoporous anodic oxidized aluminium (AOA) are presented. The anodizing process is carried out in a solution of oxalic acid containing carbon nanoparticles (CNPs). The carbon nanoparticles are studied by ultraviolet–visible spectroscopy, dynamic laser scattering (in the aggregated state), Raman spectroscopy, and infrared spectroscopy. Scanning electron microscopes are used to study the morphology of the AOA. The pore size of the porous layer is of 20–40 nm, and the pore-wall thickness is up to 50 nm. In the absence of the addition of carbon material, similar surface parameters are of 50–100 nm and 30 nm, respectively. The effect of the carbon material on the structuring of the pore layer is explained in terms of adsorption of it on the AOA during anodizing process. A high-disordered structure of carbon nanoparticles is revealed. The adsorption isotherm is obtained, and it is found that the Temkin model is the most suitable for describing the sorption equilibrium. The crystallization of AOA under hydrothermal conditions at 200°C is proposed. The addition of CNDs to the oxalic acid electrolyte reduces the pore size of obtained anodized aluminium. Carbon nanoparticles effect on the formation of the porous structure of AOA with adsorption. The advantage of CNDs over GO is the fabrication of AOA with smaller pores in mild conditions without aggressive reagents. The effect of CNDs on the porous structure of AOA can be explained, on the one hand, by its shielding by carbon nanoparticles, and on the other hand, by the ‘damping effect’ of CNDs on the faster thermal expansion of aluminium compared to Al2O3 . It is possible to obtain samples of AOA with nanoscale pores by environmentally friendly synthesis using cheap and readily available chemicals. To obtain crystalline Al2O3, hydrothermal treatment can be implemented that has the advantage of a lower crystallization temperature over calcination. [ABSTRACT FROM AUTHOR]

У різних галузях виробництва та транспорту постійно зростає попит на оливи та мастильні матеріали, які є шкідливими для довкілля складними речовинами, їх виготовлення вимагає суттєвих фінансових витрат. Актуальною задачею є створення систем керування адсорбційним очищенням відпрацьованих олив і мастил, які зможуть забезпечити вимоги до якості їх регенерування в умовах недостатнього інформаційного забезпечення та нестаціонарності значної кількості характеристик технологічної системи. Виконано аналіз властивостей сировини, адсорбенту та адсорбера з точки зору необхідного і потенційно можливого інформаційного забезпечення. Виокремлено три основні джерела нестаціонарностей: періодичне надходження нової за властивостями сировини; випадкові зміни властивостей поточної сировини та адсорбенту; поступові зміни робочих поверхонь адсорбера від взаємодії з адсорбентом та адсорбатом. Перше джерело визнано найбільш суттєвим, тому для загального алгоритму керування передбачено дві складові – керування в режимах змінної та сталої сировини (суттєві та не суттєві зміни властивостей сировини відповідно). Для кожного джерела нестаціонарності запропоновано відповідний блок адаптування для систем керування тиском і температурою в адсорбері з ПІ-регуляторами. Визначено властивості речовин, які будуть використані для корегування завдань регуляторам і параметрів їх налаштування. Створено систему взаємодії окремих блоків адаптування в обох режимах загального алгоритму керування. Для режиму сталої сировини наведено загальний вид передавальних функцій для каналів керування та запропоновано структуру системи адаптивного керування з виконанням поточної ідентифікації моделі каналу керування та перерахунку параметрів налаштування відповідних ПІ-регуляторів. Отримані результати дозволять зменшити тривалість та амплітуди відхилень показників якості регенерованих речовин від заданих значень, що підвищить ефективність роботи системи керування в цілому. Запропоновані методи можна застосувати для тих технологій, де існує проблема стабілізації властивостей вхідних матеріальних потоків, зокрема в технологіях з використанням вторинної сировини.

Предмет. У статті комплексно досліджено адсорбцію молекул побутового газу на поверхні поруватого кремнію та її вплив на електрофізичні властивості матеріалу. Мета. Визначення впливу адсорбції молекул побутового газу на електрофізичні характеристики поруватого кремнію та виявлення можливостей використання цього ефекту для розроблення ефективних газових сенсорів. Завдання. У межах дослідження проведено комплексне вивчення адсорбції газу на поруватому кремнії, виміряно зміни провідності та ємності матеріалу під впливом адсорбції газу, визначено оптимальні умови для детектування побутового газу, розглянуто можливості використання досягнутих результатів у розробленні технологій моніторингу якості повітря та безпеки середовища, а також досліджено вплив різних концентрацій побутового газу на електрофізичні характеристики поруватого кремнію. Методи. У дослідженні впроваджено методи електрофізичного аналізу для вимірювання змін провідності та ємності матеріалу. Результати. Досягнуті результати свідчать про значущий ефект адсорбції на електрофізичні властивості поруватого кремнію. Виявлено, що адсорбційний шар газу на поверхні матеріалу викликає не лише збільшення провідності, але й значні зміни в ємності, що може бути використано для розроблення ефективних газових сенсорів. Висновки. Електрофізичні зміни є показниками адсорбції та можуть бути використані для реального газового моніторингу. Існують оптимальні умови для детектування побутового газу. Визначено вплив концентрацій газу на електрофізичні характеристики поруватого кремнію. Розглянуто можливості застосування досягнутих результатів у виробництві екологічно чистих сенсорних систем для моніторингу якості повітря.

Modeling the adsorption processes and luminescence properties of Zinc Oxide (ZnO) can provide valuable insights into its applications. We used Molecular Dynamics (MD) method to investigate the adsorption processes on ZnO nanoclusters under different initial conditions. To ensure the nanoclusters were correctly structured, we applied Radial Distribution Functions (RDF) and Central Symmetry Parameter (CSP) methods. It was discovered that the number of defects in the samples had a major influence on the simulated photoluminescence (PL) spectra, which were created using a bi-Gaussian function. To assess the amount of vacancies on the surfaces of the sample, we used the relative luminescence intensity of the secondary peak in the PL spectra. To analyze the simulated PL spectra, we utilized a Gaussian fitting technique. The self-activated PL band peaking was divided by Gaussian deconvolution, which was utilized for a more in-depth analysis of the data. By researching the consequences of varying conditions on the PL spectra, we were able to obtain a better comprehension of the mechanisms behind adsorption processes on ZnO nanoclusters. Furthermore, this research enabled us to gain insight into the influences that different conditions can have on the adsorption of oxygen atoms on the nanoclusters and helped us in creating new generation gas sensors based on ZnO nanopowders and its compounds. [ABSTRACT FROM AUTHOR]

The present work is the first case where the adsorptive removal of the most commonly used fluoroquinolone antibiotic - levofloxacin (> 80 % unmetabolized in the urine) from aqueous solution as a model of wastewater treatment plant effluent by natural zeolite – clinoptilolite and its acid-modified form has been investigated under static and dynamic conditions. The effect of the inlet concentration, the flow rate and the pH value of antibiotic influent solution, also, the contact time of system zeolite/antibiotic solution on the adsorption process were examined and evaluated using the Langmuir adsorption model. The adsorption mechanism mainly composed of electrostatic interaction between the zeolite surface and adsorbate - levofloxacin. This study demonstrates and proves that natural clinoptilolite and its acid-modified form could be an efficient, eco-friendly, alternative and competitive adsorbent in terms of cheapness, selectivity and adsorption efficacy for the removal of levofloxacin from wastewaters and implemented in an industrial setting and wastewater treatment plant for purification processes. [ABSTRACT FROM AUTHOR]

Air separation products (ASPs) are an important component of many technological processes. The main industrial source of rare gases is atmospheric air. Inert gases are extracted in the form of lean concentrates during the operation of high-performance air separation plants. The presented work examines the features of rectification and adsorption-distillation technologies for the production of krypton and xenon. Currently, in the air of industrial cities there is a whole "bouquet" of harmful compounds present in significant quantities, formed as by-products as a result of the implementation of various technological processes. In the process of producing high-purity inert gases, along with Kr and Xe, air components similar in properties to them are enriched. Methods for purifying intermediate products and pure inert gases from three groups of substances: hydrocarbons; oxides of nitrogen and carbon; fluorinated gases. Purification of the krypton-xenon mixture from flammable impurities, as a rule, is carried out at all stages of the technological sequence. Hydrocarbons are separated by chemical methods, nitrogen and carbon oxides are separated by sorption. Condensation and chemical methods are promising methods for purifying krypton and xenon mixtures from fluorine-containing impurities. They provide the specified quality of gas products and a high degree of recovery. [ABSTRACT FROM AUTHOR]

Сreation of new therapeutic materials based on nucleic acids encourages the combination of the latter with materials capable of adsorbing them. One of the most promising materials for such purposes is nanocrystalline titanium dioxide due to its low toxicity, stability of its physical and chemical parameters, and high biocompatibility. Accordingly, understanding the nature of the interaction of the surface of titanium oxide with biologically active substances is a very important issue. It is also always a relevant question whether the biopolymer immobilized on the surface of a solid remains capable of serving as a reservoir for drug delivery or a tool for the treatment of a particular disease. The aim of the work was to investigate the interaction of the biologically active substance rivanol with the surface of DNA-containing titanium dioxide. It has been found that prior adsorption of deoxyribonucleic acid on the surface of titanium dioxide does not prevent its interaction with rivanol, which was confirmed by the methods of electron spectroscopy, atomic force and scanning electron microscopy. The mode of interaction of rivanol with deoxyribonucleic acid depends on the ratio of their concentrations and can be either intercalated or semiintercalated, and electrostatic. Based on the calculated thermodynamic characteristics, the process of interaction of deoxyribonucleic acid adsorbed on the surface of a solid carrier is arbitrary and occurs by an ion exchange mechanism. These hybrid organo-mineral sorbents can serve as model structures for research in biotechnological fields, be used for the development of new methods of drug or gene delivery, reservoir systems at a molecular level, and serve as biocompatible carriers. The creation of organo-mineral sorbents, which combine nucleic acids and metal oxides, contributes to the stabilization of such systems and expands the scope of their possible application in medicine and biotechnology, increasing their target specificity. [ABSTRACT FROM AUTHOR]

This work is devoted to the study of the adsorption efficiency of methylene blue and methyl orange dyes by polyaniline base (PANI), halloysite nanotubes (HNTs), and their nanocomposite (HNTs/PANI). PANI and the nanocomposite were prepared by the chemical oxidative polymerization of aniline in the absence and presence of HNTs followed by subsequent dedoping by ammonia solution. The morphology and thermal stability of the adsorbents were explored. In particular, the TEM method showed that the nanocomposite consisted of practically non-agglomerated nanoparticles with a "core-shell" morphology. Particles of pure polymer are quite agglomerated and form massive aggregates. The kinetics of decreasing the concentration of dyes in solutions upon their contact with adsorbent powders was studied by the method of electron spectroscopy. The HNTs/PANI nanocomposite was found to absorb both dyes with slightly higher efficiency than the PANI base probably due to more developed surface of the former. Processing of the obtained results of adsorption of both dyes on the studied adsorbents according to different kinetic models (pseudo-first and pseudo-second order and intraparticle diffusion) showed that in all cases this process is best described by the pseudo-second order model, which indicates the chemical nature of adsorption. The calculated adsorption capacity of the adsorbents under study appeared be quite close to the experimental one. These materials can be used as effective adsorbents for cleaning wastewaters from organic dyes. [ABSTRACT FROM AUTHOR]

Titanium dioxide is widely used as a white colorant in medicines, cosmetics, and in the food industry due to the absence of taste and smell, chemical stability in combination with excellent ultraviolet protection properties. However, its safety as a food additive was recently questioned by the European Food Safety Authority (EFSA). There is a need to deeper study the interaction of TiO2 with the human body and biological tissues. Proteins are the main type of biological molecules that can interact with TiO2 after oral administration of TiO2-containing drugs. The classical approach to measuring adsorption of organic molecules on TiO2 is based on spectrophotometry. However, the sensitivity of this method is not sufficient for measurements of the adsorption of peptides and proteins. This problem can be bypassed using peptides covalently labeled with fluorescent organic dyes possessing relatively high molar absorption coefficients and long absorption wavelengths. In this work, we decided to test the applicability of fluorescence-based quantification of peptide adsorption on titanium dioxide. Namely, we used 11 amino acids peptide labeled with fluorescein and quantified its adsorption on TiO2 at different ionic strengths of the solution. There are several advantages of using the fluorescence method to study the binding of peptides to a sorbent surface. The use of low peptide concentrations and small sample volumes allows for efficient use of resources. Reliable readout, fast measurement time, and cost-effectiveness make this method attractive for the future peptide binding studies and could potentially find application in other areas of peptide research. [ABSTRACT FROM AUTHOR]

Термохімічна акумуляція теплоти цеолітами нині перспективна для сезонного зберігання тепла. Крім того, застосування даної технології дозволяє знизити викиди CO2. Метод акумуляції тепла цеолітами ґрунтується на використанні тепла, пов'язаного з адсорбцією та десорбцією. Такий метод, порівняно із звичайним акумулюванням тепла (водяним або акумулюванням тепла з використанням теплоти фазового переходу), характеризується енергоємністю в 4-5 (теоретично 10-12) разів вище, ніж у звичайних систем. Особливу важливість має правильний вибір цеоліту. Розглянуто структуру та фізичні властивості цеолітів КА, NаА, СаА, NаХ, СаХ як такі, що знайшли найбільше практичне застосування. Для термохімічного акумулювання теплоти застосовують цеоліт типу А і Х. Розглянуто принцип роботи переривчастого цеолітного циклу з використанням сонячної енергії. Теплова потужність системи визначається інтегруванням загальної енергії, що надходить у цеолітовий контейнер протягом дня. Розподіл між потужністю охолодження та потужністю нагрівання забезпечує ефективність цеолітного циклу, як правило, від 35% до 50%. Представлений аналіз сонячної цеолітної системи, яка забезпечує опалення, охолодження та гаряче водопостачання для житлових будинків. Система безперервно працювала протягом року і забезпечувала понад 90% усіх енергетичних потреб будинку. Для ефективного застосування цеолітів у термохімічних акумуляторах теплоти необхідно не тільки вибрати правильний тип цеоліту, але й організувати правильну його підготовку та регенерацію. Застосування мікрохвильової енергії для підготовки (стадія гідротермальної кристалізації для термоактивації цеолітів, яку зазвичай проводять при 500-700 °С протягом 3-5 год) і регенерації цеолітів, дозволяє не тільки видалити адсорбційно-пов'язану вологу, але і отримати унікальну внутрішню структуру матеріалу

The processes of carbonization of sucrose-containing coatings on the surface of single-domain magnetite and magnetosensitive nanocomposite (MNC) Fe3O4/Al2O3 are studied. The MNC with a carbon surface is synthesized by the method of low-temperature pyrolysis of carbohydrates. As revealed, the used heat-treatment mode does not lead to deterioration of the magnetic characteristics of magnetite under the condition of preliminary creation of a protective layer of alumina on its surface. Differential thermal analysis (DTA) in combination with differential thermogravimetric analysis (DTGA) and programmed temperature-desorption mass spectrometry show that the carbonization of sucrose under these conditions is complete. The shape and dimensions of the Fe3O4, Fe3O4/Al2O3 and Fe3O4/Al2O3/С MNCs are investigated by the TEM method. As established, the values of the specific saturation magnetization of MNCs are consistent with the corresponding changes in the mass fraction of magnetite in the Fe3O4/Al2O3 and Fe3O4/Al2O3/С structures. The results of TEM studies and magnetic measurements indicate the formation of the Fe3O4/Al2O3 and Fe3O4/Al2O3/С MNCs by the core–shell type. Methylene blue is used to study the adsorption activity of the Fe3O4/Al2O3/С MNC surface. The results of the work can be used in the development of new magnetically controlled adsorption materials for medical–biological purposes. [ABSTRACT FROM AUTHOR]

Purpose. To depollute water contaminated by phenol using the adsorption process in a batch reactor with valorization of olive pomace for the preparation of activated carbon to be used as an adsorbent. Methodology. In this present work, study on the influence of four principal parameters on the adsorption yield during the treatment of polluted water by the process of adsorption were studied, namely: the activated carbon mass, the contact time, the phenol initial concentration and the stirring speed. In addition, the process was optimized with full factorial designs using the response surface methodology by the MINITAB software. Findings. The phenol removal by adsorption on the activated carbon made from olive pomace makes it possible to achieve an adsorption efficiency of 91 % with the use of following optimal conditions: adsorbent mass of 0.48 g, a contact time of 110.80 min, a phenol concentration of 100.98 mg/L, and a stirring speed of 462.89 rpm. Contact time and adsorbent mass showed a positive effect on phenol removal efficiency. The principal effect results illustrate that all four examined factors significantly affected the phenol removal by olive pomace activated carbon with a confidence level of 95 %. Originality. The experimental data of the phenol adsorption on the olive pomace activated carbon were examined by adjustment of a second-degree polynomial model. This model is validated by a statistical method using an analysis of variance (ANOVA). Numerical optimization was performed by the desirability function to identify the optimal parameters for maximum phenol recovery. Practical value. In order to highlight a process for treating waters contaminated with phenol, we have chosen the processes that are considered to be best suited, which is adsorption with the recovery of a waste such as an adsorbent, which is prepared by physical and chemical activation of olive pomace. The full factorial design applied makes it possible to show the influence of each parameter independently and their dependencies, as well as to find the optimal experimental conditions quickly which lead to the realization of this process. [ABSTRACT FROM AUTHOR]

The aim of presented work was to synthesize the ecologically friendly sorbents using low cost reagents based on magnesium silicates by precipitation, hydrothermal and sol-gel methods. Morphology of materials obtained was investigated by means of thermogravimetric analysis (TG-DTA), low temperature adsorption/desorption method, scanning and transmission electron microscopic studies (SEM and TEM). It has been found that all sorbents are obtained in a form of amorphous layer-structure magnesium silicates with the micro-and mesoporous structure. Based on low temperature nitrogen isotherms, the specific surface area and volume of micropores calculated by the Brunauer-Emmet-Teller (BET) and Barrett-Joyner-Halenda (BJH) methods were the greatest for the sample obtained by sol gel method (SBET = 640 m²/g, Vmicro = 0.26 cm³/g) while the sample synthesized by precipitation had the biggest volume of mesopores among the materials investigated (Vmeso = 0.39 cm³/g). As follows from TEM images, all samples consist of particles with the size from 10 up to 50 nm, the sample synthesized by sol gel method had the most homogeneous structure (MgSi-3). The ion exchange capacities of materials in the process of Cs+, Sr2+, Cu2+, and Co2+ removing from aqueous solution were determined and it was found that these properties depend on the method of materials obtaining. Data showed that magnesium silicate synthesized by precipitation method has the higher capacity toward the heavy metal cations compared to the radionuclides (1.56 and 0.96 mmol/g for cobalt and copper, respectively). For two samples synthesized by hydrothermal and sol-gel methods the increasing was fixed of capacity towards cesium and strontium ions that could be explained by the significant amounts of pores approx 2.6 nm radii in their structure. Experimental data were fitted to the Langmuir models. Analysing the data of adsorption studies, it was noted that all materials obtained can be used in adsorption technology for purification of water from heavy metal ions and radionuclides. [ABSTRACT FROM AUTHOR]

In the last decades there has been an increased interest of researchers in the obtaining anthocyanins from available and low–cost plant materials, not only as natural food dyes but also for pharmaceutical products. Among plant sources of anthocyanins chokeberries and elderberries have attracted the interest of consumers due to abundant anthocyanin contents. In this study, adsorption equilibrium and thermodynamics of anthocyanins from chokeberry and elderberry extracts by fibrous cation exchanger FIBAN K–1 were investigated. The anthocyanin extracts were obtained by macerated in 0.1 M HCl under the follow extraction parameters: solid-liquid ratio = 1:2 at 293 K for 24 h. The total anthocyanin content in the extracts was determined by pH-differential method. Adsorption experiments were carried out under static conditions, shaking mixtures of anthocyanin extracts of the berries with FIBAN K–1. The adsorption isotherms were of L-type according to the classification of Giles. The adsorption capacity of FIBAN K–1 for the chokeberry and elderberry anthocyanins increased as the temperature increased from 293 to 313 K. The Langmuir, Freundlich, and Temkin adsorption models were used to describe the experimental adsorption isotherms. These models had a good agreement with the experimental data for adsorption of the anthocyanins, but the Langmuir model was the most favorable model for studying the adsorption equilibrium of the chokeberry and elderberry anthocyanins on FIBAN K–1. Thermodynamic parameters of the anthocyanin adsorption, such as ΔG°, ΔH°, and ΔS° were calculated. The ΔG° values were negative, thus indicating that the adsorption of the chokeberry and elderberry anthocyanins on FIBAN K-1 was spontaneous and favorable process under the experimental conditions. The decrease of the ΔG° values with increasing temperature shows that adsorption is more favorable at high temperature. The ΔH° values were positive for the anthocyanins of both kind of berries, which indicates the adsorption was an endothermic reaction. The ΔS° values were positive, which means that the anthocyanins in the aqueous phase are more organized than those in the adsorbent-liquid interface. [ABSTRACT FROM AUTHOR]

Th e article is devoted to the chemical synthesis of a zeolite/polyaniline (Zt/PAn) composite and a comparative (relative to polyaniline, PAn) study of some of its physicochemical properties, in particular, structural, thermal, and adsorptive (regarding Cr(VI)) characteristics. Th e results of the studies of spectral, thermal and electrical properties of the initial natural fi ller mineral (zeolite), synthesized individual samples of polyaniline and Zt/PAn confi rmed that the latter are a composite. It was determined that the structure of the polymer in the synthesized samples of both individual polyaniline and the zeolite/polyaniline composite is mostly amorphous and corresponds to the emeraldine salt of sulfuric acid, which is deposited in the form of a thin fi lm on the surface of polycrystalline particles of a fi nely dispersed mineral. Th e study of the thermal properties of the samples of individual polyaniline and composite showed that the polymer content in the composite is approximately 50%. Th e results of studying the adsorption capacity of PAn and Zt/PAn samples proved their high effi ciency (98–99%) in removing of Cr(VI) from aqueous solutions. Th e study of the Cr(VI) adsorption kinetics at its content in the initial solutions of 200–500 mg/L showed that the process is two-stage, and the adsorption capacity of both samples of individual polyaniline and the zeolite/polyaniline composite depends on the concentration of the initial solutions. An increasing of the initial concentration of Cr(VI) in the solutions leads to a certain decreasing in absorption degree and values of adsorption at the fi rst stage of the process by both samples of the PAn and the Zt/PAn. Th e course of the second stage of sorption, which obviously has the nature of absorption, is longer, but it is during this stage that almost 98–99% removal of Cr(VI) from the investigated solutions is achieved. In particular, it was established that with a Cr(VI) content of 500 mg/L in the investigated solution, the adsorption capacity of zeolite/polyaniline composite samples is 49 mg on 1 g of adsorbent. At the same time, additional studies showed that the adsorption capacity of polyaniline in the sample of the Zt/PAn composite (i. e., without taking into account the mass of fi nely dispersed mineral fi ller) reaches 93 mg/g for the identical content of Cr(VI) in the adsorption solution. [ABSTRACT FROM AUTHOR]

Performance of an adsorptive heat pump has been studied. The factors affecting the efficiency of its work have been analyzed. Operating parameters and efficiency of adsorptive heat pumps and adsorptive heat storage devices have been compared. An algorithm of calculating the basic operating characteristics of an adsorption heat pump in heat supply systems has been proposed. It involves calculating the mass transfer coefficient, final absolute humidity of the air flow passed though adsorbent layer, the water uptake or adsorption and the useful heat of adsorption and heat of condensation, determination of heat inputs for the operation of the device such as heating the adsorbent, case of the device, hydraulic circuit, the water in the tank and adsorbed water, heat of desorption and heat of evaporation, estimation the coefficient of energy performance. The evaluation criteria of the efficiency of adsorptive heat pumps and heat storage devices have been compared. It is shown that the operating parameters of the adsorptive heat pump and the adsorptive thermal energy storage device based on composite adsorbents ‘silica gel – sodium sulfate’ and ‘silica gel – sodium acetate’ are the same, i.e. airflow rate 0.08 - 0.1 m3 /s and initial absolute humidity of airflow 0.03 – 0.04 kg/m3, which are corresponded with maximal efficiency of the device. The temperature of the humid air flow directed to the adsorbent layer is suggested to be set at 20 – 40 °C. The measures to increase the efficiency of the adsorptive heat pump are proposed. It is shown that ultrasonic air humidification allows to increase the coefficient of energy performance by almost 2 times compared to steam humidification. The obtained results can be used for developing energy-efficient heating systems of residential premises. [ABSTRACT FROM AUTHOR]

Thermochemical heat storage by zeolites is currently promising for seasonal heat storage. The method of heat storage by zeolites is based on the use of heat associated with adsorption and desorption. This method, compared to conventional heat storage (water or heat storage using phase transition heat), is characterized by an energy intensity 4-5 (theoretically 10-12) times higher than that of conventional systems. Of particular importance is the correct choice of zeolite. The structure and physical properties of KA, NaA, CaA, NaX, CaX zeolites are considered as having found the greatest practical application. For thermochemical heat storage, zeolites of type A and X are used. The principle of operation of an intermittent zeolite cycle using solar energy is considered. The thermal power of the system is determined by integrating the total energy entering the zeolite container during the day. The distribution between the cooling capacity and the heating capacity provides an efficiency of the zeolite cycle, typically between 35% and 50%. An analysis of a solar zeolite system that provides heating, cooling and hot water for residential buildings is presented. The system worked continuously throughout the year and provided more than 90% of all energy needs of the house. For the effective use of zeolites in thermochemical heat accumulators, it is necessary not only to choose the right type of zeolite, but also to organize its correct preparation and regeneration. The use of microwave energy for preparation (stage of hydrothermal crystallization for thermal activation of zeolites, which is usually carried out at 500-700 °C for 3-5 hours) and regeneration of zeolites allows not only to remove adsorption-related moisture, but also to obtain a unique internal structure of the material. [ABSTRACT FROM AUTHOR]

Layered double hydroxides (LDH) based on trivalent Al3+ and bivalent Ni2+, Zn2+ and Mg2+ ionic composition are prepared by precipitation of mixed hydroxides from aqueous solutions of corresponding salts at continuous control of pH value. In accordance with wide-angle x-ray scattering (WAXS) analysis, the synthesis conditions provide required structuration level for LDH formation. The peaks on WAXS diffractograms at angle positions of ≅12°, ≅24°, ≅36° and ≅41° as well as calculated interlayer spacing in the range of 7.4–8.8 Å demonstrate the specific structure characteristics, which are typical for synthetic LDH similar with natural hydrotalcite. Studying the features of thermogravimetric (TGA) behaviour of synthesized LDH shows a certain level of their hydrophilicity. We suppose that layered structure and capillary effects provide a moisture absorption level as high as 23% by weight. The LDH samples are characterized by four stages of weight loss. The temperature-induced water desorption (<140°С), dehydration of metal hydroxides of LDH (140–355°С) as well as thermal destruction of structure-stabilizing anions in interlayer space (>235) have determined composition-dependent characteristic peculiarities for each LDH type. Ion-exchange activity of synthesized LDH is tested using water-soluble dyes, namely, methyl orange (MO), eosine N (EN) and rhodamine B (RB), which have clear differences in chemical structure. As found, the ion-exchange ability of LDH to the cationic- and anionic-dye types is a structure-dependent parameter. Obtained LDH are efficient anionic sorbents for MO dye molecules due to a presence of the strong acidic –SO3--groups. Sorption capacity γ for MO in aqueous media reaches 121 μmole/g, whereas overall sorption efficacy ϕ is in a range of 50–97%. At the same time, all LDH demonstrate reduced efficacy for adsorption of EN dye. The sorption capacity γ and efficacy ϕ for EN are in a range of 12–109 μmole/g and 9–82%, respectively. We suppose that reducing sorption efficacy affects a weak acidity of anionic –COO--group in EN molecule. Cationic RB dye does not absorb by LDH (γ parameter is below 6 μmole/g) due to impact of repulsive electrostatic forces between positively charged dye molecules and anion-exchange centres of composite substrates. [ABSTRACT FROM AUTHOR]

Purpose. The current study was conducted to evaluate the heavy metals adsorption and sorption rate when removing them from water and processing it in the Tigris River in Samarra city, Salah El-deen, Iraq in 2021–2022 and evaluate the efficiency of zeolite for removing heavy metals, as well as to determine the high and low adsorption percentage from all heavy metals found in the river. Methodology. The study included the analysis and measurement of physical and chemical properties with low-cost natural processing with no side effects to reduce the heavy metal in the Tigris River. Finding. The results of the present study showed that the conductivity and turbidity of water decreased from 1596 to 727 µc/cm, from 343 to 22 naphthalene unit (NTU), respectively, and turbidity decreased from 633 to 491 ml/L. The concentrations of biological dissolved oxygen, total suspended solid, and total dissolved solid increased, while those of preprocessing nitrates (12.2 mg/l) differed significantly from the results of post processing (52 mg/l). Repetitive measurements showed good results for heavy metals such as Cr3+, Cd2+, Cu2+, Pb2+, Zn2+, Ni2+ and Co2+ with 16.3, 23.1, 6.3, 14.4, 8.1, 12.5 and 17.4 mg/l, respectively; the adsorption percentage was 81.6, 81.5, 86.7, 87.3, 76.4, 89.5 and 79.7 %, respectively. Originality. The work showed the efficient processing of sewage water when treated with zeolite rocks powder being low cost and easy to use to adsorb heavy metals from water. Practical value. Zeolite as a powder ground in different sizes could be used as a layer in the filter that purifies the water to become a drinking water with low heavy metal concentrations as well as with some other factors. [ABSTRACT FROM AUTHOR]

The possibility of obtaining an ecosorbent based on carbon material from rice husks modified with sulfur for the removal of Cd(II), Cu(II) ions from aqueous solutions is substantiated. The features of obtaining and modifying coal material from rice husks are noted. The temperature parameters and the duration of the pyrolysis process were determined experimentally from the conditions of the maximum content of biochar in the pyrolyzate. Sulfurcontaining biochar was obtained by chemical modification by one-stage co-pyrolysis of rice husks with sulfurcontaining reagents at a temperature of 350-400 °C. The resulting sulfur-containing ecosorbent has thermal stability and mechanical strength. A comprehensive study of the structural-porous and sorption properties of the original and sulfur-modified biochar has been carried out. The sorption capacity of the initial biochar from rice husks and sulfur-containing biochar was estimated from the decrease in the concentration of Cd(II) and Cu(II) ions in aqueous solutions of CuSO4·5H2O and Cd(NO3)2·4H2O salts before and after treatment with ecosorbent. The initial concentrations of pollution in water and soil media were 2-6 mg/L for Cd(II) and 132-396 mg/L for Cu(II). Sulfurcontaining biochar has a high absorption capacity for Cd(II) and Cu(II) ions (more than 90 %) compared to the original biochar. Its specificity is due to the formation of insoluble cadmium and copper sulfides on the surface and in the pores of the sorbent. Studies show that sulfur-modified rice husk biochar can strongly bind heavy metal ions and be used as an effective ecosorbent for the purification of aqueous solutions. The key property is the ability to form insoluble sulfide forms of metals on the surface and in the pores of the ecosorbent. [ABSTRACT FROM AUTHOR]

Aim. Study of the structure, thermal and sorption properties of iron-containing sorbent based on palygorskite. Methods. To study the structure of the composite, X-ray diffraction analysis and microscopic studies were used. Thermal analysis was carried out in order to refine the structure of materials and to establish temperature intervals for drying and utilizing sorbents. Sorption properties of materials determined by spectrophotometric method. Results. X-ray diffraction of the obtained material confirmed that particles of nano-sized zero-valent iron were fixed on the surface of palyhorskite. Transmission electron microscopy of the samples confirmed that nanoscale zero-valent iron forms spherical particles arranged in the form of aggregates and chains. The resulting composite is characterized by a uniform distribution of nanosized zero-valent iron particles on the surface of palyhorskite. The thermal analysis of the iron-containing composite based on palyhorskite confirmed that only physically bound water is released up to 170 °С, which allows us to justify the maximum drying temperature of the material. The structural transformation of the mineral begins at a temperature above 960 °С. Under these conditions, new phases are formed, which confirms the possibility of recycling spent sorbents using ceramic technology. Exothermic effects corresponding to iron oxidation temperatures in sorbents allow us to state that the size of iron particles in an iron-containing composite is smaller than the size of nano-sized zero-valent iron obtained from a solution of ferrum(II) sulfate. These data also confirm the results of X-ray diffraction. Sorption experiments confirmed that the synthesized composite effectively removes Cr(VI) and U(VI) from aqueous environments at pH values close to natural waters. An analysis of the results of sorption studies of samples dried at temperatures from 60 to 100 °C showed that the optimal temperature for drying an iron-containing composite based on palygorskite, under otherwise equal synthesis conditions, is 80 °C. Conclusions. The structure of the ironcontaining composite has been studied. The maximum drying temperature of the synthesized sorbents and the possibility of recycling spent sorbents using ceramic technology have been established. [ABSTRACT FROM AUTHOR]

Today, the development of environmentally friendly technologies for the detoxification of heavy metals in environmental objects is relevant. One of the promising areas is the production of carbon sorption materials (biochar) from lignocellulosic waste. Plant waste is a promising natural renewable material for ecosorbents. Biochar is a stable carbon-containing product that is synthesized as a result of pyrolysis (carbonization) of plant biomass. In this study, the possibility of obtaining an ecosorbent from bagasse (vegetable waste from sugarcane production) was studied. When obtaining ecosorbents for the absorption of complex compounds of heavy metal ions, chemical and biological modification of biochar was used. Sulfur-containing biochar was obtained by chemical modification by one-stage pyrolysis of raw materials together with sulfur-containing reagents. Sulfurcontaining biochar has a high absorption capacity compared to the original biochar. Its specificity is due to the formation of insoluble heavy metal sulfides on the surface and in the pores of the sorbent. Microbiological modification leads to the creation of a biosorption material for the strong binding of heavy metal ions. Sulfatereducing bacteria immobilized on the surface of biochar are able to convert sorbed heavy metals into insoluble sulfide forms. A comprehensive study of the structural-porous and sorption properties of the original and modified bagasse biochar has been carried out. Comparative analysis of the adsorption capacity of the original bagasse, biochar from bagasse, biochar modified with sulfur, and biochar with sulfate-reducing bacteria immobilized on its surface showed that chemically and biologically modified biochar from sugar cane bagasse can strongly bind heavy metal ions. It was noted that sulfur-containing biochar and biochar with immobilized sulfatereducing bacteria have a high absorption capacity (more than 90 %) with respect to Cd(II), Cu(II), Pb(II) and Zn(II) ions at an initial concentration of 2 to 5 MPC. The studies show that chemically and biologically modified sugarcane bagasse biochar can be used as effective ecosorbents for heavy metal detoxification in water and soil environments. Their main property is the ability to form insoluble sulfide forms of metals on the surface and in the pores of the ecosorbent. [ABSTRACT FROM AUTHOR]

The author proposed a method for calculating the adsorber for water removal from dichloromethane, which involves modeling the process in the Aspen Adsorption program, which is a powerful mathematical modeling tool. In his method, the author used experimental breakthrough curves, conditions of adsorption equilibrium, kinetics, heat exchange, and mass exchange. The developed method makes it possible to determine the breakthrough time and liquid temperature for different values of adsorber productivity, its dimensions, and the initial water content in dichloromethane. The author discovered that as a result of heat release in the adsorber, a "hot spot" appears, and the temperature of the liquid in it can differ significantly from the initial one. This factor is important for the selection of the size of the apparatus and the organization of its operation - since the temperature in the "hot spot" can rise to the boiling point of dichloromethane if the design is incorrect. [ABSTRACT FROM AUTHOR]

The adsorption performance of cationic dyes (methylene blue and malachite green) on barley straw modified by citric acid has been studied. Barley straw modified by citric acid is a low-cost and eco-friendly adsorbent, however the effectiveness of the adsorbent towards cationic dyes have not yet been examined. Accordingly, kinetic, equilibrium, and thermodynamic aspects of the cationic dyes adsorption from aqueous solution were studied in order to evaluate the citric acid modified barley straw efficiency. The modified barley straw was characterized versus unmodified matter using Fourier Transform Infrared spectroscopy (FT-IR). FT-IR analysis showed that modification of barley straw using citric acid allowed us to increase the number of carboxyl groups on the straw surface. Adsorption studies were conducted on a batch process, to study the effects of contact time, concentration of cationic dyes, and temperature. The results of kinetic experiments showed that adsorption process attained equilibrium within 120 and 90 min for methylene blue and malachite green, respectively, and equilibrium time for both the cationic dyes was temperature independent. The adsorption kinetics of the cationic dyes was well described by the pseudo-second order model. The equilibrium data are analyzed by the Freundlich, Langmuir, and Temkin isotherms. The experimental data of adsorption indicated more conformity with the Langmuir isotherm model for methylene blue and malachite green adsorption on the modified straw. Furthermore, the thermodynamic parameters calculated at 293–333 K showed that the adsorption of methylene blue and malachite green on the modified straw was endothermic. Negative results of ∆G° -values (between −32.1 and −24.6 kJ mol−1 ) indicated that the adsorption process was spontaneous at all the tested temperatures. Desorption of methylene blue and malachite green from the exhausted adsorbent was estimated using water and aqueous solutions of hydrochloric and acetic acids. Desorption efficiency follows the order: HCl > CH3COOH > H2O. The study has revealed that citric acid modified barley straw is an effective adsorbent and can be used as an alternative for more costly adsorbents used for cationic dyes removal from wastewater. [ABSTRACT FROM AUTHOR]

Неaling of infected ulcers and wounds, particularly in older people, is a serious problem in modern surgery. As a result of many years efforts, we have created an innovative wound care composition that has high absorptive, antiinflammatory and wound-healing capabilities and are starting the clinical study of it. The composition, which got a trade mark Pathelen®, contains nanoscale hydrophilic silica (A-300), hydrophobic silica (Aerosil® R972 Pharma) and benzalkonium chloride. This work aimed to develop an optimal pathway of industrial production, as well as methods of quality control of the drug. The examination of manufacture intermediates and the final product includes bulk density measurement, thermal analysis, IR spectroscopy, chemical methods of identification, adsorption capacity and microbial contamination control. The pathway of manufacture which consists of mechanochemical immobilization of benzalkonium chloride on hydrophobic silica surface and mixing of obtained semi-product with hydrophilic nanoscale silica is developed. Thus, a technological method is proposed for combining hydrophilic and hydrophobic nanomaterials in one preparation. The final product complies to the elaborated quality parameters. In particular, the bulk density is distributed in a range 50–60 g/L, the adsorption capacity is not less than 140 mg of protein per gram. The absence of pathogenic microorganisms and fungi was demonstrated; the quantity of non-pathogenic microorganisms meets the requirements of the European Pharmacopoeia for products in this category. The results obtained can be useful for the organization a large-scale production of the proposed drug in future. [ABSTRACT FROM AUTHOR]

The use of composite polymeric adsorbents containing components of natural origin, environmentally friendly and cheap, is one of the promising technological solutions. The article compares the characteristics of diatomite, diatomite-alginate granules and diatomite-alginate-Fe3O4 granules. Diatomite-alginate-Fe3O4 composites were synthesized by depositing magnetic iron oxide on alginate-diatomite granules. The process of synthesis and granulation of the composite adsorbent alginate-diatomite-magnetite was studied in this work. The process of applying the active magnetic phase of the adsorbent has been studied. All obtained samples were examined using electron microscopy, IR spectroscopy, X-ray phase analysis and derivatography. The dependence of the static strength of granules on the content of the solid phase (17-25 kPa) has been established. The thermal stability of the samples was studied. The adsorption of methylene blue anions from aqueous solutions has been studied. For the adsorbent alginate-diatomite and alginate-diatomite - Fe3O4, the degree of purification was 95-99 %. [ABSTRACT FROM AUTHOR]

Досліджено можливості зменшення вмісту фосфатів у скидах стічних вод прибережних населених пунктів малих річок шляхом сорбційного очищення. Для прикладу обрано верхню течію річки Прут в околицях міста Яремче (Івано-Франківська обл., Україна). Підтверджено раніше опубліковані дані автора статті та інших дослідників про те, що у річковій воді на вказаній ділянці збільшилась кількість забруднювачів, зокрема сполук фосфору. Показано, що значний вплив на цей факт мають не повністю очищені стічні води санаторіїв та інших рекреаційних закладів міста Яремче, які містять надлишок фосфат-іонів. На підставі власних попередніх досліджень та теперішньої роботи запропоновано вилучати ці іони за допомого природного сорбенту бентоніту, активованого мікрохвилями у різні способи. Один з них – опромінення бентоніту мікрохвилями у чистій воді, видалення цієї промивної води, а тоді внесення активованого у такий спосіб бентоніту у стічну воду. Цей спосіб названо "стимуляція". Другий спосіб – безпосереднє внесення необробленого (нативного) бентоніту у стічну воду, а мікрохвильовому опроміненню піддається вже приготовлена суспензія. Такий спосіб названо "пряме опромінення". Показано, що мікрохвильова активація бентоніту в обох випадках збільшує коефіцієнт вилучення фосфат-іонів із стічних вод у декілька разів, порівняно з нативним бентонітом. Виявлено, що у лабораторних умовах "пряме опромінення" дає кращі результати щодо ступеня вилучення фосфат-іонів, відносно способу "стимуляції". Показано, що у промислових масштабах здійснити "пряме опромінення" суспензії бентоніту досить складно. Подано обґрунтовану пропозицію використовувати спосіб "стимуляції" бентоніту для вилучення надлишку фосфатів із стічних вод на реально працюючих очисних спорудах.

The work presents the problems of wastewater treatment of milk processing enterprises and meat plants contaminated with organic compounds and proteins. A theoretical analysis of industrial wastewater treatment methods using zeolites of the Sokyrnytsia deposit was conducted. It was established that the most economically beneficial and safe is the adsorption method using a natural sorbent - zeolite, which ensures the lowest concentration of pollutants in the purified wastewater of food industry enterprises. The sorption properties of natural zeolite (clinoptilolite of the Sokyrnytsia deposit) to albumin protein were tested. A mathematical model for the flow curves of structured liquids and suspensions is given. The influence of hydrodynamics on the mass transfer process in a two-phase system has been established. The effect of the physical properties of the phases on the adsorption process was investigated. The theory of local isotropic turbulence to describe the hydrodynamic conditions of the process was used. Energy consumption for mixing, specific energy of dissipation and value of Reynolds and Euler criteria for each considered case were calculated. Experimental studies of the external diffusion adsorption process for zeolite-albumin solution suspensions for different stirring frequencies: 200, 300, and 500 rpm were presented. The mass transfer coefficients and values of the effective diffusion coefficient for the investigated adsorption system were calculated. The criterion equation for calculating the mass transfer coefficient was obtained. The coefficients of internal diffusion of albumin in zeolite at different speeds ranged from 7·10 -11 m ² /s to 2.62·10-10 m ² /s for 500 rpm. It was established that with an increase in the number of revolutions, there was an increase in the mass return coefficient and the effective diffusion coefficient. According to the presented results, the turbulation of the flow allows the evenly distributing of the sorbent particles in the reactor and reduces the diffusion resistance. Experimental studies of the external diffusion adsorption process for zeolite-albumin solution suspensions for different stirring frequencies: 200, 300, and 500 rpm are given. The kinetic curves of adsorption by natural zeolite for the external diffusion and internal diffusion processes were presented. The rheological and mechanical properties of the studied systems are considered. Regularities between deformations and stresses at a certain point of the system at the time  have been established. A statistical evaluation of the obtained results was carried out. For the obtained results, Pearson's test χ2 was 0.94, Student's test t = 0.002, mean square deviation; mean= 0.2. [ABSTRACT FROM AUTHOR]

Purpose. To analyse certain complex components of the rock breaking act during the well construction stipulated by the design features of the technical means of hydromechanical drilling and diversity of manifestations of hydraulic and physicochemical properties of the activated circulation medium. Methodology. Physicochemical parameters of the process of active substance adsorption from the water solutions on the rock surfaces were studied in terms of their disperse material by identifying optimal ratio in the “solid phase particles – volume of the activated solution” group with the recording of time interval of the adsorption equilibrium establishment. Features of bottomhole processes in terms of the operating modernized facilities of hydromechanical drilling were considered involving up-to-date methods of analytical analysis and experimental-laboratory studies, i.e. by using certain techniques of mathematical and physical modelling, methods for processing and interpretation of the research results by means of SolidWorks, STATGRAPHICS, МАТНСАD, and control-and-measuring equipment and materials. Findings. The peculiarities of the combined hydromechanical drilling technique have been analysed from the viewpoint of the creation of the most effi cient conditions of bottomhole rock breaking. Since a considerable degree of the development of breaking processes is the practically proved factor of hydromechanical drilling, the rationalization and intensifi cation of those processes may be achieved by means of controlled physicochemical eff ect of the surface active medium. The experimental study was carried out to analyse the directedness of the development and results of surface interaction – adsorption within the boundary of phase separation as the main factor of intensifi cation of the rock mass breaking. A comparative analysis was performed concerning the surface activity of the corresponding substances that diff er in their schemes of dissociation in a water solution whose properties are to be corrected additionally to make them close to the ones peculiar for natural drill muds. Positive infl uence of the adsorption phenomenon on the results of contact interaction of breaking elements of hydromechanical facilities was examined; this phenomenon is shown in the decelerated wear of metal surfaces. Originality. Useful infl uence of the physicochemical properties of the substances under consideration decreases beginning from the ionogenic anion-active sulfonol towards the ionogenic cation-active katapin K and to the non-ionogenic substance OP-10 (ОП-10). However, in terms of combining the compositions of the mentioned substances, it can be strengthened additionally. Practical value. The indicated laboratory and experimental studies are the basic ones to design the mode parameters of the washing programme for a hydromechanical drilling well; they belong to the main output data used while substantiating the design and technical-technological parameters of the modernized pellet impact devices. [ABSTRACT FROM AUTHOR]

The adsorption of oligomeric peroxide of sebacic acid and benzoyl peroxide on aerosils and magnesium oxide is studied. The parameters of the adsorption processes are determined. It is shown that the adsorption occurs via formation of hydrogen bonds between surface OH-groups of adsorbents and peroxide groups. The adsorption of benzoyl peroxide on the surface of aerosils and magnesium oxide is low. The thermal decomposition of oligomeric peroxide of sebacic acid and benzoyl peroxide in the presence of aerosil is investigated. The thermal decomposition of oligomeric peroxide of sebacic acid in the presence of aerosils is faster than in a homogeneous system. The corresponding activation energy increases as the aerosil content in the system decreases. In contrast to oligomeric peroxide of sebacic acid, aerosils has no effect on the thermal decomposition rate of the benzoyl peroxide. The polymerization of styrene in the presence of aerosil leads to the formation of a mineral-polymer composite. An increase in aerosil content in the polymerization system leads to a decrease in the rate of polymerization of styrene. [ABSTRACT FROM AUTHOR]

We studied the main physicochemical features of removing of arsenate from contaminated waters utilizing stabilized nanoscale iron. An inorganic kaolinite matrix was used for stabilization. The structure of adsorbents was studied using some physicochemical methods (X-ray powder diffraction and the low-temperature N2 adsorption-desorption method). It was found that the efficiency of the removal of arsenic(V) ions depends on the weight ratio of iron nanopowder to kaolinite, whereas it does not depend on the pH of the water systems in a wide range. Kinetics data were analyzed using pseudo-first-order and pseudo-second-order models. It was stated that the removal of arsenic by iron-containing composites based on kaolinite occurs relatively rapid. The adsorption kinetic was appropriately described by the pseudo-second-order model, indicating the high affinity of arsenates with the surface of the iron-containing nanocomposite. The results demonstrated that the obtained materials have a much higher sorption capacity to As(V) ions than natural silicates. The Langmuir and Freundlich isotherm equations provided good fittings for the experimental sorption data. It was shown that the sorbents based on stabilized nanoscale iron effectively remove toxic arsenic ions from contaminated water. [ABSTRACT FROM AUTHOR]

Today, the problem of purification of monoethanolamine (MEA) solutions and potassium-based, deethanolamine (DEA) activated solutions to purify gases from carbon dioxide is very acute at the enterprises of chemical industry for the production of ammonia in the synthesis scheme, at the stage of carbon monoxide conversion. Long-term use of such solutions (Carsol solution (25-28 % of КНСО3 and 1,.8 % of diethanolamine) and Benfield solution (29-30 % of КНСО3 and 2,9 % of diethanolamine)) leads to a decrease in their absorption capacity. At the stage of high-temperature regeneration, indirect processes of thermal diethanolamine decomposition occur in the volume of solutions, resulting in the formation of resinous substances and corrosion-active compounds, for removal of which additional stage for filtration of solutions on carbon filters is introduced into the flow chart. Experimental studies have been conducted at the Department of Chemical Technology and Water Purification to determine the adsorption capacity of activated bentonite clays for absorption of solutions of resinous substances and corrosion-active compounds. During the work, it has been established that bentonite clays activated by acid and alkaline activation have sufficient absorption capacity for resinous substances and corrosion-active compounds to replace the activated carbon used for these production purposes. It is revealed that the clay of acid activation is characterized by the lowest degree of absorption of the target components of the potassium solution. The clay of alkaline activation also absorbs K2CO3, KHCO3, diethanolamine and V2O5 in the process of adsorption but to a greater extent than the clay of acid activation. Activated carbon has the highest degree of absorption. Activated carbon has the highest degree of absorption. This disadvantage of activated carbon necessitates the constant replenishment of the absorbent solution with new portions of K2CO3, KHCO3, diethanolamine, which increases the production costs for purification of synthesis gas from carbon monoxide (IV).

The structure and energy characteristics of structures formed during arginine adsorption on silica surface from aqueous solution were studied by the density functional theory (B3LYP) method using a valence-split basis set 6-31++G(d,p) within the continuous solvent model (PCM) and supermolecular approximation. The equilibrium structural and energy parameters of the protonated arginine molecule in the gas phase dependent on the location of the hydrogen atom are considered including those of two possible zwitterions. The structure of the arginine ion Н2А+, which is formed when a proton attaches to a molecule or zwitterion of a given amino acid, has been elucidated. To determine the deprotonation constant of the carboxyl group in an acidic medium, the complexes of the arginine molecule (AH32+) in the state with undissociated and deprotonated carboxyl groups are considered. The simulation of the acid medium was performed by taking into account the interaction with two hydrated HCl ion pairs, which provided the protonation of the α-amino group and the nitrogen atom of amino group within the guanidine group. In the study on the interaction of an arginine molecule with silica surface in an aqueous medium, complexes containing a Si8O12(OH)7O– ion with a deprotonated silanol group, six water molecules, and an arginine molecule with a deprotonated carboxyl group were considered. It has been found that the arginine molecule is most likely to be adsorbed on slica surface with formation of hydrogen bonds between the hydrogen atoms of the α-amino group and the oxygen atom of the deprotonated silanol group. In this case, the formation of a hydrogen bond between the oxygen atom of the carboxyl group and the hydrogen atom of the neighboring silanol group is possible. Slightly less likely is adsorption of arginine molecules due to interaction of the guanidine group with silanol groups of the surface. According to the calculated data, the adsorption of the zwitterionic form of the arginine molecule from the aqueous solution is equally likely to occur due to interaction of silanol groups of silica surface with both the carboxyl group and the guanidine group. [ABSTRACT FROM AUTHOR]