Name
Sheldeshov Nikolay Viktorovich
Scholastic degree
•
Academic rank
associated professor
Honorary rank
—
Organization, job position
Kuban State University
Web site url
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Articles count: 4
In the article the mathematical model of the space charge region in the bipolar membrane is considered. The structure of the space charge region under passing of electric current, and without electric current is discussed. The results of experimental studies of water dissociation in the bipolar membrane in the presence of chromium(III) are discussed
The article discusses results of experimental research
of the influence of aprotic and proton solvents on reaction
rate of water molecules dissociation in the bipolar
membrane MB-1 by the method of electrochemical
impedance frequency spectrum. It was discovered, that
addition of organic component in aqueous solutions results
in significant influence on the parameters of water
dissociation in a bipolar region of the membrane.
The reason for this influence is the reduction of the
mass fraction of water in solution and, consequently,
in a bipolar region of the membrane, which itself reduces
the rate of the dissociation reaction. Another
reason for the influence of the organic solvent is its effect
on the network of hydrogen bonds existing in water
and aqueous solutions. Depending on the nature of
organic solvent and its concentration, the network of
hydrogen bonds may be strengthened, or destroyed,
thus facilitating removal of the proton involved in the
reactions between water molecules and catalytic centers
in cation-exchange and anion-exchange layer of
bipolar membrane, or retarding removal of proton.
This leads respectively to speed up or slow down the
rate of dissociation in the bipolar region of the membrane,
as well as changing the constants of the dissociation
reaction of water. Introduction of organic solvent
in solutions, which are in the contact with bipolar
membrane, is a convenient method of investigating the
role of solution composition on the rate of proton
transfer between water molecules and catalytic centers
in the membranes
The results of study of bipolar membrane – analogue
of MB-2, modified with chemically introduced chromium
(III), iron (III) and nickel (II) hydroxides by the
method of frequency spectrum of electrochemical impedance,
by infrared spectroscopy and scanning electron
microscopy in combination with X-ray spectrum
analysis are presented. It is shown, that sequential
treatment of cation-exchanger, contained in cationexchange
membrane, with metal salt solution and alkali
solution does not result in formation of complex
compounds of these metals with ionic groups of ion
exchanger. It was found that in these conditions the
presence of heavy metals in the phase of cationexchanger
confirmed by X-ray analysis, however,
crystals of hydroxides of heavy metals are not detected
in the size range of 1000 nm to 20 nm. These heavy
metal compounds are thermally unstable and their
catalytic activity in the reaction of dissociation of water
molecules decreases with increasing temperature
during heat treatment. The introduction of low-soluble
hydroxides of d-metals (chromium (III), iron (III),
nickel(II)) by chemical method can significantly improve
the electrochemical characteristics of a bipolar
membrane. The most effective catalysts in water dissociation
reaction are the hydroxides of chromium (III)
and iron (III) and, as a consequence, membranes with
these hydroxides have a lower value of overpotential
compared with original membrane at the same current
density
The article presents a mathematical model of the ion transport across phase boundary exchange membrane / solution. The border is considered as an object in space, endowed with all the physical and chemical properties that are inherent physical and chemical phases. It is regarded as a special physical and chemical environment, having a distributed exchange capacity in which there is space charge dissociation of water molecules. The size of this object is estimated in the range of 1-300 nm. The surface morphology of industrial membrane type MK-40, ÐœA-41 and ÐœA-41P was investigated experimentally by scanning electron microscopy (REM). There was analyzed the amplitude of average surface roughness. In this article, the reaction layer is modeled as a region that forms as a relief morphology of the membrane. Membrane properties are due to the properties of the solution and the properties of the membrane. To determine the dependence of Q(x) is proposed procedure for assessing the proportion of solid phase in the total volume of which can be seen in the vertical cross section microprofile on the membrane surface line. Height multivendors determine the reaction layer zone on frame of model. Influence of surface morphology on the V-A characteristics and the sizes of the convective instability of cation-exchange membrane evaluated numerically simulating the hydrodynamic flow conditions using a solution of the Navier-Stokes equations. The transfer of a strong electrolyte such as NaCl ions through the thin layer of the reaction layer is considered. The place of nanomodel in the structure of a three-layer membrane system is showed. The distribution of the concentration of ions in the system, the charge density distribution and the dependence of the integrate charge with extent nanolayer is present. How to change the shape of the space charge and its integral value with one is investigated