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Vol 72, No 4 (2017)
- Year: 2017
- Articles: 8
- URL: https://bakhtiniada.ru/0027-1314/issue/view/9935
Article
The influence of polyetherimide on gelation and phase separation in epoxy systems
Abstract
In the process of curing under thermostatic conditions, the time dependence of active and reactive components of the dielectric permittivity of epoxy amine compositions that contain a thermoplastic substance is studied in a wide range of electrical frequencies. The times of gelation and vitrification are calculated from the dielectric data and the onset of the phase separation is identified. The curing behavior established by dielectric spectroscopy is confirmed by viscometry and optical microscopy. During the phase separation, the morphology of the precipitating phase differs between samples depending on the chemical nature of the curing agent.
161-166
Preparation of reagent indicator papers with silver triangular nanoplates for chemical analysis
Abstract
An impregnation method to prepare reagent indicator papers with silver triangular nanoplates (TNPs) is developed. The conditions for obtaining modified papers (type of paper, method for applying TNPs, and drying conditions) allowing for an acceptably uniform distribution of the TNPs are chosen. The spectral characteristics of the prepared materials are studied. The presence of an intense TNP surface plasmon resonance band in the diffuse reflectance spectra of the modified papers, which is linearly related to the content of the TNPs in the samples, as well as the lability of its position and shape in the presence of some substances, gives rise to the prospects of using the prepared materials as test-tools in chemical analysis.
167-173
TXRF determination of mercury(II) in water in combination with liquid–liquid microextraction
Abstract
A highly selective hybrid way of TXRF determination of mercury(II) in drinking water at the level of n(10–2–100) μg/L is developed. The technique of preconcentration of mercury(II) ions includes directly suspended droplet microextraction with benzene in the form of an iodide molecular complex. The proposed method of determination is characterized by its high degree of sensitivity and reproducibility (cmin = 8 ng/L, sr = 0.12 (100 ng/L)). The accuracy of the analysis results is confirmed by the introduced–found method.
174-177
Electrochemical monitoring of biogenic microelements
Abstract
This paper reviews literary data on electrochemical monitoring of biogenic microelements in natural and industrial objects. Special attention is paid to the questions of the trace determination for a number of transition metals by stripping voltammetry (SVA) after the adsorptive enrichment of these elements as dimethylglyoxime (DMG) complexes on the surface of a working electrode. The analytical possibilities of adsorptive SVA with the use of mercury-based and mercury-free electrodes are compared. The paper is dedicated to the memory of Vadim Mikhailovich Ivanov.
178-182
Determining benzo(a)pyrene in objects in light industry by HPLC after preconcentration with aluminosilicate
Abstract
The procedure of benzo(a)pyrene determination based on the sorption of a preliminarily concentrated analyte using aluminosilicate and subsequent detection by HPLC provided by a fluorimetric detector is developed for certain objects in the light industry. The advantages of the proposed method are their high metrological characteristics, ease of performance, affordability, and the ability to replace the imported adsorption materials. It can be applied in laboratories engaged in monitoring the quality of the facilities in light industry.
183-186
A tristimulus colorimetric study of the acid–base properties of 6,7-dihydroxybenzopyrylium chlorides in solutions
Abstract
The acid–base equilibria of 6,7-dihydroxybenzopyrylium chloride derivatives in solutions are studied by tristimulus colorimetry. The ionization constants of their functional groups are determined. Possible schemes of the equilibria and the distribution diagrams of the ion-molecular forms of the reagents are proposed depending on the pH of the medium. It is shown that tristimulus colorimetry can be used to determine the protonation and hydroxylation constants of the dyes. The relation between these constants and the charges on the oxygen atoms and 2-C atoms of the benzopyrylium ring is established.
187-191
Study of chemical composition of Asparagus racemosus roots
Abstract
The chemical composition of Asparagus racemosus roots is studied by the methods of gas chromatography and high-performance liquid chromatography. Marker substances characteristic of this type of raw materials are revealed. The dioscin content in the roots of A. racemosus is quantitatively determined.
192-195
Studying the sorption kinetics on peat ions of iron(III) and copper(II) from wastewater
Abstract
The sorption kinetics on the peat of copper(II) and iron(III) ions from model solutions are studied. The sorption process takes place quickly and is almost complete after 20 minutes. Based on the processing of the experimental absorption curves of the equations of chemical kinetics and diffusion it is established that the sorption process is in the diffusion mode. The stage of the chemical interaction of the metal ions with the functional groups of peat also contributes to the overall speed of the process. The efficiency of the sorption process is determined and the possibility of Using peat as a sorbent for purifying wastewater from the copper( II) and iron(III) ions at industrial sites is shown.
196-199