Sorption Layer Research Articles

Passive isothermal film with self-switchable radiative cooling-driven water sorption layer for arid climate applications

Reducing substantial energy demand of active heating, ventilation, and air conditioning in arid climates is of paramount importance. Here, we develop a millimeter-scale passive isothermal film that maintains temperature near 25 °C without relying on energy consumption solely through natural phenomena. A radiative cooling unit comprising polydimethylsiloxane (PDMS) with diffraction grating and fused SiO2/Ti/Ag film facilitates radiative cooling during daylight hours. Net thermal energy is stored through water desorption of porous materials (latent cooling) and dissolution of ammonium nitrate in water (endothermic reaction). At nighttime, thermal emission is suppressed by the destructive interference of PDMS diffraction, and thermochemical reverse reaction occurs to sustain temperature in response to heat loss from the ambient environment. It reduces cooling and heating loads by approximately −1.1 and 0.3 kW m−2, respectively, throughout a full day. Our results indicate the potential of designing a passive system suitable for human habitation without an active system.

SORBENTS BASED ON THE Ni,Fe-LAYERED DOUBLE HYDROXIDES AND ITS MAGNETIC NANOCOMPOSITES FOR DEACTIVATION AND PRECONCENTRATION OF Cs(I) AND Sr(II) IONS FROM AQUEOUS SOLUTIONS

The synthesis and comparative evaluation of the adsorption capacity in relation to Sr(II) and Cs(I) ions of the carbonate form of Ni(II)/­Fe(III)–layered double hydroxides (NiFe-LDH) and their nanocomposites was carried out. At first, Fe3O4 nanoparticles having a crystallite size of 20–50 nm were obtained by Fe(III) precursors. In the second step, Fe3O4 nanoparticles were embedded in NiFe-LDH matrix by the co-precipitation at hydrothermal conditions and subsequent condensation of the basic solution containing Fe3O4nanoparticles. The influence of the physicochemical parameters of the synthesized sorbents on the efficiency of magnetic solid phase extraction of these radionuclides from aqueous solutions was investigated. Their effectiveness in extracting Sr(II) and Cs(I) ions with a change in the pH of the aqueous medium was evaluated, as well as sorption isotherms on the obtained sorbents at pH0 4.5–5.0 were obtained, and their analysis and processing were carried out to establish the mechanism of sorption extraction at all le­vels of filling of the sorption layer with analytes. Equilibrium adsorption data were analyzed using Freundlich and Langmuir isotherm models. Of the models tested, Langmuir isotherm expressions were found to give better fit to the experimental data compared to the Freundlich model. The applicability of mathematical models for estimating the kinetic patterns of sorption of radionuclides on NiFe-LDH and their magnetic nanocomposites was analyzed. The adequacy of the Boyd and Morris – Weber diffusion models in the initial section (up to F = 0.4–0.6) of the kinetic curves is shown. Kinetically, the growth of effective diffusion coefficients and adsorption rate constants is observed in the series: Fe3O4<NiFe-LDH<Fe3O4@NiFe-LDH, and the pseudo-second-order kinetic model most accurately reflects the patterns of sorption of these radionuclides. Due to high sorption efficiency and manufacturability, the obtained sorbents are promising for water purification from radioactive pollutants.

Use of carbon materials for constructing a closed water treatment system

Water purification by solar distillation has been deemed to be a green and promising approach for the production of potable water from undrinkable water resources. Carbonaceous materials have been well-known for the application of the sorption layer in the solar-to-steam system. Herein, both carbon spheres (CSs) and carbon dots (CDs) were synthesized by a one-pot hydrothermal method at 180 °C for 12h and they were used for constructing a closed water treatment system, in which CSs served as solar-thermal membranes in harvesting water and purifying Fe3+ ions in condensed water, while CDs played a role in the determination of Fe3+ ions in water. The evaporation rate of the CS membrane reaches 1.046 kg m−2 h−1 under 1 sun illumination and the efficiency treatment of Fe3+ is about 80%. The limit of detection obtained in the evaluation of Fe3+ ions in water by CDs was 3.61 μM. This work represents a significant step forward, as it opens the concept of constructing a closed water treatment system.

Effect of the Sorption Layer on the Protection Time Provided by Anti-Smog Half-Masks.

This paper presents the results of a study examining the protection time of half-masks containing different types and quantities of carbon sorbents. The protection time afforded by the half-masks was determined by analyzing the adsorption of three substances harmful to human health at their maximum allowable concentrations. Two of the tested half-masks showed comprehensive protection against pollutants contained in smog. Among the tested half-masks, the one with the best protective properties was identified. The longest protection time (over 8 h) was recorded for toluene, followed by over 7 h for sulfur dioxide, and only 2 h for cyclohexane. The morphological structure of nonwovens incorporating the carbon sorbents was examined under a microscope. The study showed that protection time depends on the size of activated carbon particles incorporated in the nonwoven structure as well as on their distribution. Based on these results, we identified the most effective morphological structure of the sorbent in the nonwovens.

Current aspects of the wound process treatment using dressings (bandages)

The review provides information concerning the assortment of modern wound dressings (bandages) which are presented on the pharmaceutical market. The studied group of dressings varies widely in chemical composition and active pharmaceutical ingredients. It has been determined that the development of modern wound dressings provides for the realization of a complex effect on the wound process, which is achieved by the multi-layer structure of the dressing (bandages) with clearly defined functions of each component – the contact layer reduces adhesion to the wound surface; sorption layer provides irreversible sorption, retention and inactivation of wound exudate; pharmacologically active layer influences the main factors of wound process pathogenesis; outer isolating membrane generates wound occlusion. Conclusions. The events of recent years which related to the Anti-terrorist operation / the Joint Forces Operation in Ukraine indicate the unresolved problem of combat surgical trauma treatment. This is an important issue for the Medical services of the Armed Forces and the health care system of Ukraine. This necessitates expanding the range of wound dressing (bandages) with combined action for military medicine. It has been determined that the treatment in the purulent-necrotic phase of the wound process, it is advisable to use wound dressings with strong osmotic and antibacterial activity and low adhesion to the wound surface. In the second phase of the wound process, it is advisable to use wound dressings with moderate osmotic activity and a combination of antibacterial and reparative properties. In the final phase of the wound process, wound dressings should prevent drying of the wound surface as well as protect and stimulate the growth of granulations.

AERIAL PART FERULA TENUISECTA ALTERNATIVE INDUSTRIAL RAW MATERIAL FOR THE PRODUCTION OF TEFESTROL SUBSTANCE

The main losses of tefestrol have been identified and the advantages and disadvantages of the existing technology in the production of the substance from the aerial parts of Ferula tenuisecta have been established. It was found that the final product obtained by the existing technology has a green color that does not meet the requirements of the Pharmacopoeia article. The stage proposed of extraction of the sum of esters of sesquiterpene alcohols from the aerial part of Ferula tenuisecta and purification of the obtained extract, allowing to subsequent obtain the substance of tefestrol without green color. It has been shown that the use of activated carbon makes it possible to remove the green color of the extract. To purify tefestrol from other esters of sesquiterpene alcohols and accompanying substances, a chromatographic separation on silica gel is proposed under the following conditions: the ratio of the amount introduced into the column and the sorbent is 1 : 20; the ratio of the height of the sorption layer to the column diameter is 4 : 1; elution rate 35 l/h.m2. To obtain the pharmacopoeial substance of tefestrol is proposed, crystallization of a technical product from a mixture of ethyl acetate with hexane in a volume ratio of 1 : 3. Based on the results obtained, technology has been developed for obtaining the tefestrol substance from the aerial part of Ferula tenuisecta. Using this technology 70.96% of the substance of tefestrol is obtained from the content in the raw material, according to the existing technology 33.9%.

Effect of steric hindrance on lubrication and corrosion resistance of oil soluble ionic liquids

In this study, three sterically-hindered quaternary ammonium phosphate ionic liquids (N11116-D.P, N111616-D.P, N88816-D.P) were synthesised, and the effect of the alkyl chain structure of oil soluble ILs on their lubricating and anti-corrosion abilities were investigated. In contrast to conventional ILs, oil soluble ILs exhibit prominent van der Waals interactions owing to the complex structure of the nonpolar alkyl chain, leading to special interfacial adsorption. It was found that when lower steric hindrance was present, the amount of ILs adsorbed increased, resulting in a compacted ad sorption layer with more mass, which facilitated the formation of more antiwear compounds in the tribochemical reaction and a hydrophobic layer that isolated the corrosive environment.

Thermodynamics of chalcocite dissolving in solutions of flotation reagents

This work describes the formation of the ionic composition of the sorption layer during the concentration of copper-lead and pyrite-copper-zinc ore. The thermodynamics of the sorption layer of a sulfhydryl collector (sodium diisobutyl thiophosphate and potassium butyl xanthate) on the surface of chalcocite under various conditions of its oxidation has been studied using pH- and redoxometry. The nature of the change in the chalcocite electrode potential depending on the type of modifier and storage device, as well as on pH, has been experimentally clarified. The differences in the collective action of a one-component accumulator and a mixture of flotation reagents were revealed based on the thermodynamics analysis of the flotation process reactions. In addition, the optimal conditions for the flotation were determined. It was found that the quality of the concentrate is mainly influenced by two factors, such as the pulp redox potential and the pH of the medium. Mathematical equations of the optimal reagent and hydrodynamic enrichment regimes with the maximum dissolution of ore minerals in solutions of flotation reagents were modeled.

Sorption of Fulvic Acids onto Titanium Dioxide Nanoparticles Extracted from Commercial Sunscreens: ToF-SIMS and High-Dimensional Data Analysis

Titanium dioxide nanoparticles (n-TiO2) are common ingredients of sunscreens and are often released into surface waters during usage. Once released, the surface chemistry of n-TiO2 changes by interacting with dissolved organic matter (DOM). In previous studies, these interactions were investigated using model n-TiO2 and; therefore, do not account for the complex composition of the coating of n-TiO2 aged in sunscreens. Taking advantage of a mild extraction method to provide more realistic nanoparticles, we investigated the potentials of time of flight-secondary ion mass spectrometry (ToF-SIMS) combined with high-dimensional data analysis to characterize the sorption of fulvic acids, as a model for DOM, on titanium dioxide nanoparticles extracted from ten different commercial sunscreens (n-TiO2 ⸦ sunscreen). Clustering analysis confirmed the ability of ToF-SIMS to detect the sorption of fulvic acids. Moreover, a unique sorption pattern was recognized for each n-TiO2 ⸦ sunscreen, which implied different fractionation of fulvic acids based on the initial specifications of nanoparticles, e.g., size, coating, etc. Furthermore, random forest was used to extract the most important fragments for predicting the presence of fulvic acids on the surface of n-TiO2 ⸦ sunscreen. Finally, we evaluate the potential of ToF-SIMS for characterizing the sorption layer.

Molecular Structure of Adsorbed Water Phases in Silica Nanopores

The adsorption of water vapor in silica nanopores with different pore morphologies and surface hydrophilicities was studied to quantify the densities and thicknesses of the water sorption layers and deduce their molecular structures. Water adsorption to surface hydroxyls is described by a multilayer sorption model. At low pressure, the water adsorption isotherms are largely independent of pore size and the adsorbed amounts scale with the surface hydroxyl density. Adsorbed-phase densities corresponding to the adsorption of two water molecules per surface hydroxyl group are found in the first adsorbed water layer for a wide range of surface hydroxyl densities. The densities and layer thickness values found in narrow pores indicate that patchy adsorbed layers form if not enough water molecules exist for a full layer, which coexist with dry pore surface regions. This behavior indicates cooperative adsorption effects, i.e., a preference for the formation of hydrogen bonds between water molecules bound to surface hydroxyls. In narrow pores, pore condensation limits further growth of the sorption layer, and in larger pores and at the planar quartz surface, a second adsorbed water layer is formed, which can hold up to approximately 4 additional water molecules per surface hydroxyl group. The water molecules in these thicker adsorption layers arrange such that the sorption layer density is similar to the bulk water density. Pore confinement limitations on the sorption layers are observed in pores with radii of as large as 8 nm. Molecular dynamics modeling reveals two preferential orientations for water molecules adsorbing to surface hydroxyl groups and suggests an intralayer structuring in the adsorbed monolayer. Adsorbed water molecules in the sorption layer are bonded to the surface hydroxyl group via the donation and acceptance of hydrogen bonds.

ESTIMATION OF TWO-PHASE RELATIVE PERMEABILITIES BASED ON TREELIKE FRACTAL MODEL AND PRESSURE DROP AROUND GAS BUBBLES IN POROUS MEDIA

In order to estimate relative permeabilities of brine–gas, a semi-analytical model based on fractal theory is proposed. The model simplifies porous media as treelike nanotubes, the single nanotube’s flow has been branched out into whole pore network of core sample through treelike fractal theory. Two-phase flow description in sole nanotube, based on a setting of gas bubbles pushing continuous water phase ahead, solves pressure drop around brine and gas bubbles by Stokes’ viscous force, Laplace equation and Fairbrother–Stubbs bubble film thickness formula, Bretherton bubble pressure drop. By substituting the other three classic formulas into Bretherton expression, the iteration equation of pressure drop around a single gas bubble is acquired, the number of gas bubbles is multiplied and the gas phase pressure drop is calculated. Through merging small bubbles into a large bubble, the relative permeabilities of two phases can be solved by introducing Poiseuille’s law and Darcy’s law. After getting the fundamental data, pore size distribution data and viscosity of two phases, relative permeability curves can be drawn, revealing comprehensive elements including wettability, fluid viscosity, saturation, morphological characteristics. The calculated curves cross each other on the right half of the [Formula: see text]-axis, meet the features of real production, flowback difficulties of hydraulic liquid and well production dropping quickly, also show identical trend with experimental data. Through a series of sensitivity analysis, to some extent, the influence on relative permeabilities is compared of different fractal models, different film thickness, bubble length, water sorption layer thickness, elastic deformation of pores.

Sorption Preconcentration of Volatile Organic Compounds in Air Analysis with a Change in the Configuration of the Sorption Layer in a Transition from Sorption to Thermal Desorption

Sorption Preconcentration of Volatile Organic Compounds in Air Analysis with a Change in the Configuration of the Sorption Layer in a Transition from Sorption to Thermal Desorption

Сhromatographic methods for the study of organic extractants of transformer oil

THE PURPOSE. In order to control the technical condition of oil-filled electrical equipment, a number of new analytical methods have recently been created to determine the ultra-low concentrations of impurity compounds in transformer oil. An analysis of the literature data showed that at this stage of the analytical procedure significant errors may occur that worsen the quality of control of the technical condition of oil-filled electrical equipment, and in some cases make its results meaningless. The published literature practically does not discuss the problem of sample preparation of transformer oil, which negatively affects the quality of analytical control, that is, the reliability of the results and, accordingly, the diagnosis of oil-filled electrical equipment. METHODS. The paper discusses a sample preparation system for transformer oil, which is based on various methods for extracting target components from it. The adsorption process is used, the preparation of chemical derivatives, various types of extraction, liquid, gas, solid phase and fluid, as well as using low temperatures, extraction in microwave, magnetic, electromagnetic and centrifugal fields. It is shown that liquid extraction with an organic solvent is widely used from all sample preparation methods, with the help of which furan compounds resulting from the destruction of paper insulation are extracted from transformer oil. The disadvantages of sample preparation using liquid-phase extraction and the possibility of using solid-phase extraction on various adsorbents for this purpose are discussed. RESULTS. The results of an experimental study of the sorption properties of various organic solvents with respect to porous materials differing in the structure of their surface are presented. We used zeolite-bearing rocks of the Tatar-Shatrashansky deposit, synthetic zeolites NaX-13A. Using the ascending variant of liquid column chromatography, the absolute retention values of standard extractants were determined and their dependence on the length of the sorption layer of the porous material was found. CONCLUSIONS. It was shown that the highest retention times for all studied adsorbents are observed for organochlorine extractants, chloroform, carbon tetrachloride, dichloroethane, trichlorethylene. For N. Hexane is a relatively small interaction. Histograms are given of the effect of the retention time of standard sorbates (extractants) on their physicochemical nature.

Removing copper and nickel from contaminated water with vermiculite-sungulite materials

The environmental impact of non-ferrous metallurgy sites is a well-studied and thoroughly described phenomenon characterizing industrially developed areas. New techniques are being developed and adopted to help reduce the amount of metal compounds released in the environment by the industry. The so-called fugitive sources of pollution, which include polluted areas surrounding industrial sites, have been a recent focus of attention. This paper considers the possibility to use vermiculite-sungulite materials obtained by concentration of tailings produced by a phlogopite mine in Kovdor (Murmansk Region) as a sorption material to be used for removing heavy metals from contaminated ponds of the Monchegorsk Industrial Area in the Murmansk Region. A series of experiments has been conducted during which sampled water was treated with vermiculite-sungulite materials. This sorption treatment technique was established to be efficient. Some resultant solutions have residual concentrations of metals <10 mcg/L, with the purification efficiency exceeding 85%. The factor determining the process of removing nickel and copper from contaminated water includes pH, which is reached as a result of water interacting with the above materials. In the equilibrium state, provided the рН level in the system is maintained above 8.5, vermiculite-sungulite materials can keep metals sorbed thus preventing their migration from the sorption layer. The findings show that due to the use of finely dispersed materials the concentrations of copper and nickel can be lowered from 10 mg/L to a few micrograms. This research study was funded and supported by Kola MMC.

The study of radium and polonium sorption by a thin-layer MnO2-CTA sorbent

The work focuses on sorption of radium-223 and polonium-210 by a thin-layer MnO2-CTA sorbent. The maximal sorption of Ra (≈ 80%) and Po (≈ 12%) was achieved after 1 day of sorption. For Ra, decrease of quality of alpha spectrum was observed during sorption that can be explained by its diffusion into MnO2 and support layers. The average thickness of the sorption layer was determined to be 456 nm, whereas the energy loss of 5 MeV α-particles in MnO2 is approximately 270 keV μm−1. Scanning electronic microscopy and optical microphotographs confirmed flat morphology of the sorbent’s surface and no morphology changes as a result of sorption. In contrast to radium, the values of full width at half maximum (FWHM) of the 210Po alpha peak just slightly increased from ≈ 40 to ≈ 80 keV after 2 weeks of sorption that can be explained by larger ionic radius of polonium and another sorption mechanism, which is probably a partial replacement of manganese by polonium in the manganese dioxide crystal lattice. The observed phenomenon of increasing FWHM of alpha peaks from flat sorbents was suggested as an instrument for study the diffusion of alpha emitters in flat sorption-active layers.

Photochemical production of gold films on the surface of fabric materials

Abstract A technology for producing gold films on the surface of fabric materials has been developed, which provides for preliminary wetting of the fabric product with aqueous solutions of gold (III) chloride. In this case, a sorption layer of gold chloride is formed on the surface of fabric materials. Then, when drying these products under sunlight, physicochemical and photochemical processes occur, leading initially to the formation of monovalent gold chlorides, which, having semiconductor properties, provide the release of elemental gold. After washing of by-products on the surface of the material remains an ultra-thin film of gold, which has a sufficiently strong grip on the base. Since the proposed technology does not require special equipment it can be used to apply functional films of gold on various products of technical, household and medical purposes.

The Nature of the Increased Efficiency of Sorption-Stimulating Preparations Containing Non-Ionic Surfactants for Pre-Sowing Seed Treatment.

The effect of the introduction of a non-ionogenic surfactant Polysorbate 20 into a sorption preparation (CB-H-BYA) on the structure of sorbent layers formed on the surface of spring wheat seeds during their pre-sowing treatment has been studied using electron microscopy. According to the results, an increase in the efficiency of sorption preparations containing Polysorbate 20 is based on an intensification of the bentonite aggregate disintegration into individual montmorillonite particles and a formation of more dense protective sorption layer providing a better protection of seeds against allelotoxins on the seed surface. The introduction of non-ionogenic surfactants into the preparation increases a sorption capacity of a bentonite-humus complex that results in a decreased gibberellin activity in a solution. Therefore, to achieve the maximum physiological activity of gibberellin in a preparation solution, it is necessary to increase its concentration from 100 to 300 mg/L. As a result, the stimulating effect increases from 36 to 55%.

Hydraulic and sorption performances of soil amended with calcium-magnesium composite powder against natural arsenic contamination

Excavated soils and rocks, containing toxic metals and/or metalloids from geogenic sources, are usually generated in huge volumes at construction sites. And the post-excavation leaching of these toxic metals and/or metalloids with low concentrations, but higher than the environmental standards, is a major environmental concern. A sorption layer method was developed as a cost-effective countermeasure for treating and reusing such excavated soils and rocks. The method utilizes a permeable soil layer, with sorption capacity at the bottom of the embankment, to retain the chemicals of concern that have dissolved in the leachate. Clean host soil, amended with toxic metal-immobilizing agents, is often used as the sorption layer material to strengthen the sorption performance. This study examined the feasibility of applying decomposed granite soil, amended with calcium-magnesium (Ca-Mg) composite powder, as the sorption layer material against the natural contamination of arsenic (As). The hydraulic and sorption performances, along with the effect of the mix proportions and curing periods, were evaluated through batch sorption tests, hydraulic conductivity tests, and up-flow column percolation tests. The results showed that the sorption performance increased by 15 times when using an additive content of 5% Ca-Mg and that hydraulic conductivity was maintained at around 1 × 10−6 m/s. Neither the hydraulic nor the sorption performance was strongly affected by curing periods up to 28 days. The sorption performance increased with the addition of the Ca-Mg agent of up to 5% in the batch sorption tests. The permeable hydraulic property, with an improved sorption capacity due to the soil-agent mixture, indicated that it is a promising material for use with the sorption layer method for treating huge amounts of soils with low levels of contamination.

Study of the sorption properties of solvents in thinlayer and column chromatography

Much attention is paid to the consideration of the causes of transformer oil aging under the influence of technogenic and natural factors. The paper insulation destruction mechanism is considered, as a result of which furan compounds are formed that enter the transformer oil and worsen its dielectric characteristics. The characteristics of the domestic transformer oil grade GK-1 obtained using the technology of hydrocracking in a hydrogen medium are given. Furan compounds are formed in used transformer oil, which are monitored using chromatographic analysis methods according to standard procedures. The group composition of transformer oil was determined using thin layer chromatography. As a solvent used n. Hexane. To extract furan compounds from transformer oil, various organic solvents are used, the physicochemical properties of which are given in this work. It was found that the retention time of the studied sorbates corresponds to an increase in their boiling points for ethyl acetate, methyl ethyl ketone and dodecane. In the case of isopropanol, which has a close boiling point with ethyl acetate and methyl ethyl ketone, a significant increase in retention time is observed, which is associated with the formation of an intermolecular hydrogen bond. The dependence of the spot diameter of furan substances on their concentration was established under conditions of thin-layer chromatography on Sorbfil plastics. Moreover, the most effective separation is characteristic of furfural. In this case, the chromatographic spots are small in size with good fidelity. The ascending mode of column liquid chromatography was used to determine the dependence of the retention time of standard sorbates on the length of the Silyochrome S-80 sorption layer, which is parabolic. It was found that the highest retention times are characteristic of ethoxyethanol and isopropanol, which is consistent with the known theoretical principles of liquid chromatography. Histograms of the effect of the retention time of standard sorbates on their nature and boiling point, where isopropanol and 2-ethoxyethanol are extreme, are presented. In this case, isopropanol having a lower boiling point than 2-Ethoxyethanol is retained on the sorbent more strongly, which is associated with the formation of intermolecular hydrogen bonds with surface silanol groups of the sorbent.

Development of a novel composite resin for dissolved divalent mercury measurement using diffusive gradients in thin films

In this work, a composite resin gel incorporating thiol-modified metal double hydroxide (TM-MDH) nanoparticles is developed for application in diffusive gradients in thin films (DGT) devices to sample and concentrate divalent Hg (Hg(II)) in water and sediment samples. The DGT device uses the TM-MDH resin as a sorption layer and an agarose gel as a diffusive layer. Complete digestion of the TM-MDH resin after sampling can be achieved in 5 mL of 12 N HCl solution for 30 min for direct aqueous Hg(II) analysis. The recovery of Hg(II) uptake onto the resin in aqueous solution reaches 95.4 ± 1.9%. The effect of ionic strength and pH on the performance of DGT device for Hg(II) is assessed. It is found that there is no significant difference on Hg(II) uptake over a pH range of 3.5–8.5 and an ionic strength range of 1–500 mM NaCl. The diffusion coefficient of Hg(II) at 25 °C was estimated to be 9.48 × 10−6 cm2/s at 50 μg/L solution. The sorption capacity of TM-MDH-DGT for Hg(II) reaches 41.0 μg/cm2. Field validations performed in reservoir water and in contaminated paddy soil demonstrate that the developed TM-MDH DGT device can accurately determine Hg(II) concentrations in these samples and outperform traditional sampling methods for both high and low Hg(II) concentrations.