Papers by Keyword: Sorption

Abstract: Представлен оригинальный метод получения композиционных сорбционных материалов на основе смешанных ферроцианидов Ni-K и Zn-K в композиции с силоксан-акрилатной эмульсией и полиэтиленом. Оригинальность метода заключается в гидрофобизации материала за счет введения полиэтиленовых волокон в структуру ферроцианидов. Изучены особенности извлечения микро- и микроконцентраций катионов Cs ⁺ , а также радионуклидов Cs-137 из морской воды в статических и динамических условиях. Экспериментальные значения сорбции аппроксимируются согласно уравнениям Фрейндлиха, Ленгмюра, Ленгмюра-Фрейндлиха, а значения максимальной сорбции G _max и константы адсорбционного равновесия K _lрассчитаны. Установлено, что сорбенты, синтезированные с использованием полиэтилена, при степени очистки морской воды от ионов цезия до 99% обладают наилучшими сорбционными характеристиками. Значения K _p для цезия при использовании исследуемых сорбентов могут достигать 10 ⁵ мл / г, что свидетельствует об их перспективности для очистки морской воды от радиоактивного цезия. Описанный подход является примером простого и доступного технологического синтеза эффективных и востребованных на практике сорбентов высокого эксплуатационного качества.

Abstract: The article presents the results of studies on recovery of lithium from reservoir brines using both commercial and synthesized aluminum hydroxide and hydrated manganese oxide as sorbents. The research results showed that, when using commercial aluminum hydroxide and synthesized hydrated manganese oxide as sorbents, lithium recovery from brine was 21.8 and 20.1%, respectively. Studies were conducted on lithium chemisorption on freshly precipitated aluminum hydroxide, which was obtained by adding aluminum chloride solution and tri-calcium hydro-aluminate to the brine. Chemisorption of lithium was carried out under the following conditions: T = 50 °C; AlCl₃ solution concentration - 120 g/dm³; molar ratio Li/Al = 7; pH equal = 8.0-8.8; holding time with stirring 1 h. The degree of lithium extraction from brine was 71%; lithium capacity of freshly precipitated Al (OH)₃ was 5.9 mg/g. During calcareous leaching of lithium-aluminum precipitate, lithium was extracted into a solution by 74.7%.

Abstract: Composite membranes were prepared for nanofiltration of aromatic solvents. Cross-linking with AlCl₃ was used to improve the stability of the PIM-1 selective layer in aromatic solvents like toluene, benzene and xylene. Nanofiltration performances of obtained membranes were tested with 4 different aromatic hydrocarbons and with 3 solvents from other classes of solvents. Obtained permeability for aromatic hydrocarbons was above 8,5 kg/m²·h·bar and retention of Remazol brilliant blue R dye with molecular mass 626 was up to 96 %. It was shown that permeability results correlated with Hansen solubility parameter and distance parameter between polymer and solvent. PIM-1 has higher permeability for non-polar hydrocarbons due to higher affinity between polymer and solvent.

Abstract: Humic substances are the main component of soil organic matter and they actively interact with substances in soils, including pollutants. Humic acid-clay mineral composite materials can be considered as prospective and low-cost sorbents for contaminant removal. The aim of this study is to develop clay mineral and humic acid composite materials and to characterise their possible applications. For this research, montmorillonite, kaolinite and bentonite were saturated with three types of humic substances: technical humic acid from lignite, humic substances extracted from raised bog peat (Latvia) and technical K humate from lignite. Obtained sorbents were characterized using FTIR. The sorption was characterised according to the chosen clay mineral and humic acid type and concentration. Comparing the influence of clay minerals and humic substances on humic matter sorption, it has been found that the sorbed amount of humic substances depend on chosen humic substances and/or clay mineral. Obtained sorbents were used for sorption of chlorpromazine. Results indicate that the most perspective sorbents for chlorpromazine removal are bentonite and bentonite modified with humic acid. However, montmorillonite-humic composites also can be used for removal of chlorpromazine from water.

Abstract: A series of resorcinol-formaldehyde resins (RFR) has been prepared and studied in terms of Cs-137 uptake efficiency from solutions (0.75М NaOH-2.25M NaNO₃) intended for processing spent ion-exchangers. Sample synthesized at molar ratio of resorcinol to formaldehyde of 1.8:2.2 and solidified at 210 °C (sample RFR-3-1-210) has shown the best sorption-selective performance and chemical stability. Implementing RFR in dynamic sorption scheme enables to reduce its decay due to short contact time. In dynamic conditions, after feeding 1000 bed volumes of the solution, RFR 3-1-210 maintains its sorption properties after 6 sorption-desorption cycles.

Abstract: A significant increase in the amount of pollution (including heavy metals) that enter the hydrosphere as a result of human activity, sanitary requirements that are imposed on the quality of water, lead to the search for effective ways and methods of its purification. Wastewater from many industrial plants contain heavy metal salts, including manganese compounds. The sorption of manganese (II) cations by a composite sorbent from model solutions under static conditions was studied, to determine the possibility of using this sorption material in wastewater treatment. The characteristics of the sorption capacity of the composite sorbent are determined. It was established that the static exchange capacity of the composite sorbent is 0.9 mg/g; distribution coefficient - 47.34 l/g; the degree of purification of the solution is 99.9%. The empirical sorption equations for the manganese (II) cation are found, the sorption isotherms are constructed. It is established that the sorption process is described by the Freundlich equation. Experiments have shown that the composite sorbent is effective in extracting manganese (II) from aqueous solutions. Experimental data suggest that the sorbent studied can be used to clean industrial wastewater from manganese compounds.

Abstract: A novel self-adhesive wound dressing product was developed using a hydroxyethyl cellulose (HEC) hydrogel layered with a TAPE-gelatin bioadhesive. This wound dressing was then evaluated for its sorption properties through diffusion and swelling tests, and the parameters analyzed were hydrogel formulation, wound dressing thickness and adhesive layer thickness. Results showed that the wound dressing produced using 6% NaOH/5% thiourea in the crosslinking solution, with 2.5 mm hydrogel thickness, and 0.2 mm TAPE-gelatin thickness had the highest water absorbed. Lastly, analysis on swelling kinetics based on a previous study was conducted to determine the diffusion coefficients for the composite wound dressing.

Abstract: As the demand for sustainable environment friendly materials increases, the biocomposites such as wood-polymer composite (WPC) have gained more attention in past years. Wood wastes and by-products like sawdust, chips, bark and wood residues as well as recycled polymers can serve as raw materials for production of WPC. However, there are still many issues obtaining WPCs, mainly a poor compatibility between a hydrophobic polymer matrix and a hydrophilic wood filler. In the present study, mechanical and mechanochemical activation of aspen wood waste were performed to increase their compatibility with recycled polypropylene matrix in the WPC, and the impact of both methods on the biocomposite properties were studied. It was found, that mechanochemical activation (MCA) of aspen wood particles leads to increased hydrophobicity of the obtained WPC compared to the WPC with mechanically activated (MA) particles. Work of adhesion with water was remarkably lower for the WPC modified by MCA which also correlates with moisture sorption results. Surface free energy of the WPC modified by MCA was lower compared to the WPC modified by MA, mostly due to decreased the polar component of surface free energy. The modulus of elasticity (MOE) were competitive for both the WPC formulations, however, MCA led to increased flexural strength of WPC compared to MA.

Abstract: The efficiency of iron oxy-hydrate application for cleaning aqueous media from arsenic has been studied. It is proposed to precipitate the active layer to a coarse-grained carrier to improve filterability. Metallurgical alumina and quartz sand are considered as carrier materials. Conditions for the synthesis of inorganic sorbent based on iron oxy-hydrate are established. The dependence of the sorbent capacity on the pH of the solution is determined. IR spectra of the sorbent before and after sorption of arsenic are given, and the mechanism of sorption of arsenic is proposed. The data on the capacity of the obtained sorbent modifications for the sorption of As (III) ions under static conditions are presented.

Abstract: The efficiency of application of various iron compounds for purification of aqueous media from arsenic has been studied. It is proposed to apply the active layer to a substrate of a coarser material to improve the filterability. Alumina, quartz, and crystalline sulfur are considered as carrier materials. The conditions of inorganic sorbent synthesis based on iron oxyhydrate (IOH) are determined. Effect on sorbent capacity for As (V) of the concentration of iron and sodium sulfate in the solution at the modification of alumina is determined. The results of X-ray phase analysis and scanning electron microscopy are presented. The data on the capacity of the obtained sorbent modifications for the sorption of As (V) ions under static conditions are presented. The dependence of the capacity of the sorbent for As (V) on the method of synthesis of IOH and the type of carrier is established. It is shown that the sorbent on the basis of SiO₂ possesses maximum capacity.