Keywords: sorption

Kinetics of Cu(II) removal from aqueous solution with the use of Fe3O4/C nanocomposite

Abstract
this work studied the sorption kinetics of the Fe3O4/C nanocomposite obtained by heating polyacrylonitrile (PAN) and FeCl2∙4H2O in air, the preparation procedure of which was described in the previous works [9, 10]. The main task was to calculate the sorption characteristics and check the practical application of this nanocomposite, that is the possibility of purification from heavy metals from water sources, verified on the example of modeling the sorption of copper ions from an aqueous solution of copper(II) acetate hexahydrate, hence the equations of diffusion (Morris-Weber model) and chemical kinetics (Lagergren's pseudo-first order, Ho and McKay's pseudo-second order), as well as the Elovich chemosorption model were applied. Analysis of the data illustrated that the diffusion of copper ions inside the pores of the nanocomposite and chemical interactions between copper ions and functional groups of the sorbent surface, such as hydroxyl, carboxyl, carbonyl, etc., which are typical of carbon sorbents, contribute to the total sorption rate. Experimentally, the capacity of this nanocomposite for copper sorption was 208.4 mg/g, however, modeling showed that this value could theoretically be higher by 37%.
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DETERMINATION OF MERCURY IN WINE SAMPLES USING OF SILICA, MODIFIED BY POLYHEXAMETHYLENUGANIDINE

Abstract
The aim of the work was the development of a sorption-atomic-absorption method for determining mercury after its separation from wine samples in the form of a complex with unithiol on modified polyhexamethylene guanidine silica. The sorption-atomic absorption determination of mercury in wines was performed using the cold-steam method. The developed method is characterized by a low detection limit and a sufficiently high accuracy and satisfactory reproducibility.
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METHODS OF SORPTION CONCENTRATION OF SURFACE ACTIVE SUBSTANCES

Abstract
The scarcity of water resources and their pollution speaks about the need to provide the population with environmentally safe drinking water. This problem is very relevant at the present time. Accumulating in reservoirs, surface-active substances exert a strong toxic effect on flora and fauna, impair the organoleptic characteristics of water, and hinder the processes of self-purification of water bodies. The processes of destruction of the majority of surfactants in natural waters occur rather slowly. One of the effective ways to combat water pollution by surfactants is to prevent them from entering water. Many of the techniques are laborious enough, they require expensive equipment, they are not precise enough and express. Therefore, the development of simple, rapid, accessible techniques suitable for determining the content of surfactants of different classes in soils, sewage and other objects is still an important and urgent task. The article describes methods of sorption concentration of surface-active substances with the use of inorganic residues, and with the use of natural and synthetic sorbents. In the methods of sorption concentration of surfactants with the use of inorganic residues, as precipitating agents and sorbents, oxides of calcium, magnesium, aluminum, marble chips, bischofite, magnesium sulfate can be simultaneously used. A method using electrochemical destructive oxidation is also used. Natural sorbents include various natural porous hydrophobic materials, which, due to their structure, possess considerable sorption ability. Natural sorbents are very diverse because of the difference in structure and conditions of their formation. These include inorganic products of natural precipitation reactions (bauxites, laterites, ferrolites, etc.), clays (hydroaluminosilicates), active earths (sili-cates), as well as organic precipitates and products of the transformation of organic substances of plant and animal origin (muds of lakes and seas, humus, peat, lignite, etc.). The process of application is quite expensive, which sig-nificantly reduces the economic efficiency of the use of natural sorbents.
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SORPTION-PHOTOMETRIC DETERMINATION OF ANIONIC SURFACTANTS IN THE PRESENCE OF ORGANIC REAGENT

Abstract
The article describes the characteristics of a class of surfactants and the use of substances in the petrochemical industry. The classification of anionic surfactants is considered. The main structural elements of the structure of substances of the considered class are presented. A brief description of the most commonly used methods for the analysis of anionic surfactants is given. Advantages of using photometric, extraction-photometric and spectrophotometric methods for the determination of anionic surfactants using triphenylmethane dyes are described. In the course of the study, the content of the anionic surfactant (sulfonol) in the solution was monitored spectrophotometrically using the indicator reaction with malachite green. The use of the method in question to study sorption processes in a surfactant system is justified by the fact that surfactants are able to form complex compounds (ionic associates) with organic reagents with characteristic light absorption bands.
The results of a photometric determination of an anionic surfactant (sulfonol) using an organic reagent, malachite green, are presented. The effect of the acidity of the environment on the process of adsorption of a component in aqueous solutions is described. A calibration graph for determining the concentration of the component is given.
The main thermodynamic parameters of sulfon adsorption on activated carbon, such as enthalpy (∆H), isobaric-isothermal potential (∆G) and entropy (∆S) sorption were determined during the research. The obtained research results can be used for quantitative determination of the component and modeling of adsorption mechanisms.
The main characteristics of the sorption kinetics of a surfactant (sulfanol) on active coal are calculated. Isotherms of sorption kinetics are given. The possibility of purification from the above-described component using the sorbent under consideration is described.
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