Moscow University Chemistry Bulletin最新文献

A piezoactive nanofiber composite PVDF film with TiO₂ nanoparticles included in it was synthesized by electrospinning. The composition, morphology and structure of the films were investigated. The high efficiency of films in the processes of piezophotocatalytic decomposition of organic dye in water is shown.

The dependence of the surface plasmon resonance frequency on the change in the permittivity of the medium near metal nanostructures opens up the possibility of using them as a universal platform for creating biochemical sensors. Improving the sensitivity of such systems makes it possible to detect the smallest change in the refractive index upon the adsorption of a small amount of analyte on the surface of plasmonic nanoparticles. One of the approaches to improve the sensitivity of nanostructure arrays is to reduce the effect of the substrate. Upon excitation of surface plasmon resonance, a significant part of the locally enhanced electric field, which determines the possibility of detection, is located in the volume of the substrate material and is inaccessible to analyte molecules. We studied the sensitivity of an array of gold triangular nanoprisms to a change in the refractive index of a medium depending on the height of an extra dielectric layer under the particles using finite difference numerical simulation in the time domain. The sensitivity reaches 42 ± 6% at a layer height of 15 nm, while a further increase in the spacer thickness does not significantly increase the sensitivity of the system.

Currently, the issue of minimizing the environmental impact of anthropogenic activities and improving the quality of water resources is topical. The paper presents an overview of research on advanced oxidation processes and their use for the removal of organic dyes from wastewater. Among wastewater treatment technologies based on advanced oxidation processes can be divided: oxidation of organic dyes with hydrogen peroxide in the presence of iron(II) ions when irradiated UV light (photo-Fenton), exposure of wastewater to ultrasound in the presence of iron(II) ions and hydrogen peroxide (sono-Fenton), the photoelectrochemical generation of hydrogen peroxide in the presence of iron(II) ions and UV light irradiation (photoelectro-Fenton), as well as in the presence of heterogeneous iron-containing compounds and hydrogen peroxide (Fenton-like process). These advanced oxidation processes are used for the removal of organic dyes which are highly chemically stable because the other treatment methods, such as biological oxidation is inefficient.

This paper estimates uncertainty budgets in determining the content of impurities of 15 elements (P, Mn, Fe, Cu, Zn, As, Se, Ag, Cd, Sn, Sb, Te, Tl, Pb, Bi) in nickel samples by inductively coupled plasma mass spectrometry (ICP-MS) and high-resolution glow discharge mass spectrometry (GDMS). It is validated by analyzing a certified standard nickel sample (assessed using Student’s simple t test). The main sources of uncertainty in the results of analysis by two methods, including sample preparation and calibration graph, are presented. The total and expanded uncertainties for the two methods are compared. A nickel alloy of the ZhS6U type is analyzed by the ICP-MS and GDMS methods of industrial melting of and the results are compared with a modified Student’s test.

The homogeneous process of cysteine oxidation in a stirred reactor is studied. We found that oscillatory mode can be realized in the cysteine–cobalt(II) oxygenated complex system under certain experimental conditions. Various approaches to explain the experimental data indicate that the processes are deterministic.

New complexes of Cu(II), Ni(II), Co(II) and Ag(I) with 1,4-bis(3-phenyl triazenyl) benzene are obtained. Using the methods of IR, EPR, electron spectroscopy, and chemical and thermogravimetric analyses, the composition and structure of the obtained complexes are studied. Based on IR, EPR, electron spectroscopy, and chemical and thermogravimetric analyses, a square-pyramidal structure of the complexes is proposed. The unusual behavior of the temperature dependence of the electrical resistance of the silver complex is detected, namely, the presence of a maximum on the temperature dependence of the resistivity in the range of ~240 to 300 K.

The influence of the concentration of zinc introduced into HZSM-5 on its acidic and catalytic properties in the conversion of ethanol into high-octane components of motor fuels in the temperature range of 350 to 450°C is studied. Based on the IR spectroscopy data, it is shown that an increase in the zinc content in the zeolite from 1.0 to 3.0 wt % leads to a redistribution of the acid sites, i.e., to a decrease in the concentration of strong Brønsted acid sites (B) and an increase in the concentration of medium strength Lewis ones (L) (a decrease in the B/L ratio from 3.53 to 0.44). All this has a decisive influence on the isomerizing and aromatizing selectivity of the catalyst. The maximum selectivity for isoparaffins (43.9%) has been achieved on the zeolite containing 2.0 wt % of zinc and a B/L ratio of 0.66. The catalyst obtained at 300–350°C corresponds to the Euro-5 standard in terms of the content of benzene (<1.0 wt %), aromatic (<30.0 wt %), and olefinic (<2.0 wt %) compounds.

The kinetics of lipoic acid adsorption on the surface of silver is studied by the methods of quartz crystal microbalance and wetting. The multilayer nature of adsorption is established. The optimal conditions for the formation of a mono- and bilayer of lipoic acid on a solid surface are determined. The results obtained make it possible to predict the use of silver nanoparticles as carriers of lipophobic drugs in biomedical applications.

A structural-kinetic model, which allows us to obtain two rheological equations for describing the dependence of the first difference of normal stresses on the shear rate in the region of low rates and in the region of high shear rates, is considered. The obtained equations are approximated to the experimental data for various structured systems, namely, melts and polymer solutions. The regularities of the change in the coefficients of the rheological equations with a change in the concentration of the polymer in the solution and with a change in the molecular weight of the polymer are explained in terms of structural-kinetic concepts.