RU2350692C1 - Electrochemical modular cell for processing of electrolytes solutions - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: invention is related to processes of electrochemical preparation of different chemical products by electrolysis of electrolytes solutions of different concentration. Cylindrical electrochemical cell for processing of solutions comprises internal hollow tubular anode, external cylindrical cathode, permeable tubular ceramic diaphragm installed between them that separates Interelectrode space into anode and cathode chambers, units for installation, fastening and tightening of electrodes and diaphragms installed at the end parts of cell, and accessories for supply and drain of processed solutions to and from electrode chambers. Cathode, anode and diaphragm are installed in units and are connected to accessories for supply and drain of solution with creation of cell working part, along the whole length of which constancy of hydrodynamic characteristics of electrode chambers and characteristics of electrical field is preserved. Cathode and anode are made of titanium tubes, at that ratio of cathode chamber cross section to sum of areas of anode chamber and diaphragm cross sections makes 0.9-1.0, and length of cell working part makes 15-25 external diameters of anode.

EFFECT: intensification of electrolysis processes.

9 cl, 14 dwg, 6 tbl, 11 ex

Description

Application area

The invention relates to the field of chemical technology, in particular to devices for electrochemical processing of electrolyte solutions, and can be used in the processes of electrochemical preparation of various chemical products by electrolysis of electrolyte solutions of various concentrations, including in processes associated with electrochemical regulation of acid-base, redox properties and catalytic activity of dilute aqueous solutions of electrolytes, the concentration of which is predominant It is essentially in the range of 0.001–0.1 mol / L, as well as of other liquids with low electrical conductivity.

State of the art

In applied electrochemistry, electrolyzers of various designs are used to treat water, aqueous solutions, and produce various chemical products, in particular flow electrolyzers with flat electrodes [see, for example, US patent No. 5427658, С25В 9/00, 15/08, 1995] or electrolyzers with coaxially arranged cylindrical electrodes and a diaphragm between them [see, for example, Japanese Patent No. 02274889 A, C25B 9/00, 1989].

The closest in technical essence and the achieved result is an electrochemical modular cell containing coaxially placed cylindrical external and internal electrodes made in the form of pipe sections, and a coaxially permeable diaphragm made of ceramic installed between them [see international application WO 98/58880, C02F 1/461, 1998].

This technical solution is selected as a prototype.

The well-known technical solution allows you to create modular electrolyzers that achieve the required performance by connecting the required number of electrochemical modular cells, which reduces the cost of designing and manufacturing electrolyzers of fixed capacity, unify parts and assemblies, reduce the time of installation and repair of such electrolyzers.

When using the well-known electrochemical modular cell, effective treatment of water or aqueous solutions with low energy consumption is achieved. The device is quite simple to operate, relatively easily combined into blocks, which are flow diaphragm electrochemical reactors of a given capacity (power).

However, the known device has several disadvantages.

The known device is intended for the treatment of solutions of metal chlorides and cannot be used effectively for processing solutions of other types. In addition, it is known that cylindrical electrolyzers with a diaphragm have relatively low performance characteristics and are significantly inferior in performance indicators to electrolyzers with bulk or fluidized electrodes [see, for example, Fyoshin M.Ya., Smirnova MG Electrochemical systems in the synthesis of chemical products. - M .: Chemistry, 1985, pp. 216-223, Pl. VIIII.6, Fig. VII.34].

Disclosure of invention

The technical result achieved by using the present invention is to enable the intensification of electrolysis processes in a cylindrical diaphragm cell by improving the design of the cell and choosing the optimal ratio of the sizes of the main elements - electrodes and diaphragm. This result is enhanced by the use of a diaphragm and electrodes with a different ratio of the areas of geometric (apparent) and true (physical) surfaces, as well as through the use of a diaphragm made of materials in the cell, the combination of which gives the capillary-porous diaphragm high electroosmotic activity. Also achieved by the technical result is the expansion of the functionality of the cell when processing solutions of electrolytes with different chemical composition and concentration.

The specified technical result is achieved by the fact that in a cylindrical electrochemical cell for processing solutions containing an inner tubular anode, an outer cylindrical cathode and a permeable tubular ceramic diaphragm located between them, separating the interelectrode space into the anode and cathode chambers, nodes for installing, attaching and sealing the electrodes and diaphragms placed on the end parts of the cell and devices for supplying and removing processed solutions to and from the electrode chambers, cathode, anode and the diaphragm is installed in the nodes and connected to the devices for supplying and draining the solution with the formation of the working part of the cell, along the entire length of which the hydrodynamic characteristics of the electrode chambers and the characteristics of the electric field are constant. The cathode and anode are made of titanium tubes, while the ratio of the cross-sectional area of the cathode chamber to the sum of the cross-sectional areas of the anode chamber and the diaphragm is 0.9-1.0, and the length of the working part of the cell is 15-25 outer diameters of the anode. The anode can be made of a titanium tube with a developed outer surface on which an electrocatalytic coating is applied, and the ratio of the true (physical) surface area of the anode to the true surface area of the cathode is equal to or greater than unity. The cell diaphragm is made capillary-porous, electroosmotically active, and the outer true surface of the diaphragm is equal to or smaller than the true surface of the cathode, and the inner true surface of the diaphragm is equal to or smaller than the true surface of the anode, but smaller than the true outer surface of the diaphragm. In the cell, the product of the interelectrode distance by the quotient of dividing the sum of the true surfaces of the anode and cathode by the total volume of the electrode chambers is 3.9-4.1.

In a cylindrical electrochemical cell for processing solutions, the ceramic diaphragm is made of alumina grains surrounded by zirconia particles partially stabilized by rare or rare earth oxides, and has the following composition: alumina - 60-90 wt.%, With at least 98% phase composition alumina are in alpha form, zirconia is 10-40 wt.%, while at least 98% of the phase composition of zirconia is in tetragonal modification. To stabilize the tetragonal phase of zirconia, additives are used - one or more oxides selected from the group consisting of yttrium, scandium, ytterbium, cerium, gadolinium oxides in a total amount of 1.0-10.0 wt.%.

The attachment points of the electrodes and the diaphragm can be made in the form of one or more parts of dielectric material each, and the devices for supplying and discharging the treated solution to and from the electrode chambers are made in the form of channels and nozzles combined with the parts of the nodes.

The anode cavity can be equipped with devices for supplying and removing coolant.

The cell can be made in such a way that the attachment points of the electrodes and the diaphragm are made in the form of one or more parts of dielectric material each, devices for supplying and / or withdrawing the treated solution to and from the cathode chamber are made in the form of channels and nozzles combined with the parts of the nodes and devices for supplying and discharging the treated solution to and from the anode chamber are made in the form of nozzles connected to the internal cavity of the anode and installed at its ends, while in the end parts of the anode you olneny holes.

The attachment points of the electrodes and the diaphragm in the cell can be made in the form of one or more parts of dielectric material each, devices for supplying and discharging the treated solution to and from the cathode chamber are made in the form of holes and nozzles located at the end sections of the cathode, and devices for feeding and drainage of the treated solution to and from the anode chamber is made in the form of nozzles connected to the inner cavity of the anode and installed on its ends, while in the end parts of the anode there are holes and I. In the body of the anode, additional holes can be made evenly spaced along its length along the entire length of the working part of the cell.

The fact that the cathode, anode and diaphragm are installed in the nodes with the formation of the working part of the cell (see Fig. 1), along the entire length of which the hydrodynamic, thermophysical and electrophysical characteristics of the electrode chambers remain constant (the given roughness of the surfaces forming the walls of the electrode chambers is the same radial the distance between the cylindrical surfaces of the electrodes and the diaphragm in all cross sections of the working part of the cell, the same thickness of the diaphragm, anode and cathode titanium pipes along the entire length of the working part cell, the same electric field in the diaphragm body, the same electrical resistance between the electrodes in any cross section of the working part of the cell), allows to intensify the process of electrochemical exposure due to the uniform, with the same longitudinal speed at all points of the cross section of the electrode chambers, the movement of the treated solutions , which corresponds to the operating conditions of the ideal displacement chemical reactor. In this case, the speed of gas-liquid displacement fronts, each of which, due to continuous electrochemical exposure, differs in temperature, concentration, chemical composition and physicochemical properties (due to different amounts of dissolved and free gases), is determined only by the volumetric flow rate of solutions at the inlet to each of electrode chambers. In the working part of the cell, subject to size ratios, there are no stagnation zones, zones of predominant or delayed flow of solutions. The formation of slow-flow zones and stagnation zones in the electrode chambers of electrolyzers is usually accompanied by the accumulation of an increased number of products of electrochemical reactions with higher electrical conductivity than the initial electrolyte solution. Due to the formation of inhomogeneity of the conducting medium, the redistribution of electric current lines occurs, which is accompanied by local temperature fluctuations, which, in turn, enhance the action of other factors generating the flow heterogeneity. Self-sustaining and self-developing thermophysical, electrochemical and hydrodynamic fluctuations in the working chambers of electrochemical systems lead to an unproductive expenditure of energy and a decrease in the efficiency of the processes of electrochemical conversion of liquids. The implementation of the anode and cathode of the electrochemical cell in the form of titanium tubes with low thermal inertia, avoids the occurrence and development of longitudinal (along the cell axis) thermal interference of the fronts of the gas-liquid medium moving in the electrode chambers of the cell. The steady-state hydraulic mode in the chambers of the working part of the cell is ensured when the points of entry and exit of the electrolyte solution into the chamber and from the chamber are located at a distance equal to or greater than the width of the electrode chamber into which the electrolyte solution is introduced and discharged.

The ratio of the cross-sectional area of the cathode chamber of the cell to the sum of the cross-sectional areas of the anode chamber and the diaphragm should be 0.8-1.0, and the length of the working part of the cell should be 15-25 outer diameters of the anode. It is in this range of values of the ratio of the cell parameters that the fluid is circulated in the electrode chambers in the form of microtoroidal flows, in which each microvolume of the treated fluid in contact with the electrode surface is repeatedly in contact with it (see Fig. 3). The occurrence of microtoroidal fluid flows in the electrode chambers increases the degree of use of the initial components of the electrolyte solution, the achievement of the best conditions for supplying the starting materials to the electrode surface and the best conditions for the removal of reaction products from the electrodes with the simultaneous removal of electrolysis gases in the form of tiny bubbles that do not increase the resistance of the medium in the electrode chambers.

In addition, the effect of the emergence and stable existence of microtoroidal flows provides effective mixing of the starting materials and reaction products in each section of the working part of the cell during the movement of the gas-liquid medium. In this case, the effect of the occurrence and existence of microtoroidal flows, due to the above ratio, allows us to consider the volume of the gas-liquid mixture located between any two cross sections as arbitrarily close as a toroidal microreactor of ideal mixing. Thus, the fulfillment of this ratio contributes to the intensification of the most important processes - hydrodynamic, which include the supply of starting materials to the electrode and the removal of products of electrochemical reactions from the electrode, as well as the processes of removal of electrolysis gases from the interelectrode space.

A decrease or increase in this ratio can be achieved by changing the cross-sectional area of the cathode chamber and the cross-sectional area of the anode chamber. A change in the ratio leads to a disruption of the microtoroid structure of the flows in the electrode chambers, a decrease in the mass transfer rate, and, accordingly, a decrease in the efficiency of electrochemical processes. An increase in the diaphragm cross section with a constant cross section of the electrode chambers leads to an increase in the electric and hydraulic resistance of the diaphragm, which also leads to a decrease in the efficiency of the process. A decrease in the diaphragm cross section with a constant cross-section of the electrode chambers leads to a decrease in the mechanical strength of the diaphragm, an increase in its permeability, and a decrease in the adsorption-chemical and electroosmotic activity, as a result of which the efficiency of separation of highly active products of electrochemical reactions during cell operation is impaired. The length of the working part of the cell should not be more than 25D ₂ and less than 15D ₂ , where D ₂ is the outer diameter of the anode. When the length of the working part of the cell is less than fifteen external diameters of the anode, the time of electrochemical treatment of liquids in the cell is short, which reduces the efficiency of the cell. The increase in the length of the working chamber over twenty-five outer diameters of the anode leads to a significant increase in the hydraulic resistance of the cell and increased energy consumption due to excessively high gas filling of the electrolyte.

The anode can be made of a titanium tube with a developed outer surface on which an electrocatalytic coating is applied, and the cathode can be made of a titanium tube with an inner surface smoother than the surface of the anode, which is achieved by treating the working surfaces of the electrodes using any of the known methods, such as sandblasting, electrochemical etching, chemical etching, polishing, electropolishing, grinding with a grinding tool, etc. This allows you to adjust the ratio of true (physical, active, active) surfaces of the anode and cathode along the entire length of the working part of the cell. This ratio should be equal to or greater than unity, despite the fact that the apparent (geometric) surface of the anode, as follows from the design, is smaller than the geometric surface of the cathode, since the outer diameter of the anode is smaller than the inner diameter of the cathode. The developed physical surface of the anode allows to reduce the effective density of the anode current and thereby increase the service life of the anode electrocatalytic coating by several times. The developed surface of the anode due to the large number of microgeometric protrusions and depressions, the size of which does not exceed 10 μm, allows you to create microelectrocatalytic sections that differ in the magnitude of the electrode potential (see figure 2). On the protrusions, due to the greater density of the micro scattering current, the oxidation potential is higher than in the depressions, where the micro scattering current density is lower. During the electrochemical treatment of dilute solutions of electrolytes, this allows one to obtain products of anodic oxidation due to a variety of chemical reactions that differ in kinetics and various equilibrium potentials. Due to the developed surface of the anode and the very low concentration of electrolyte ions, thick ion ions are formed around metastable reaction products, such as ozone, singlet oxygen, hydrogen peroxide, chlorine dioxide, directly in the dense and diffuse region of the double electric layer (DEL) near the anode surface -hydrate membranes that keep them in solution for a long time and prevent mutual neutralization, which is unavoidable under ordinary conditions of chemical interaction.

When processing concentrated electrolyte solutions, the developed surface of the anode allows anodic oxidation to be carried out with minimal anodic polarization, which ensures a reduction in heat loss.

The small geometrical surface of the anode, in comparison with the large geometrical surface of the cathode, forms a radial distribution of electric field lines that are condensed to the center and provide an accelerated supply of the starting materials to the anode surface at a distance of the electric field of the diffuse part of the DES, 10 ^-5 ... 10 ^-4 centimeters, as well as accelerated removal of products of electrochemical reactions from the field of action of the diffuse part of DES to the volume of the solution.

The relatively smooth surface of the cathode provides the formation of small hydrogen bubbles and, due to the uniform structure of titanium in the surface and near-surface layers, reduces the rate of dissolution of hydrogen in the metal (hydrogenation process).

The diaphragm must be capillary-porous, have high electroosmotic activity and have a different degree of microroughness on the surfaces facing the cathode and anode. Along the entire length of the working part of the cell, the inner and outer surface of the diaphragm is made with a given, different, roughness, namely, the outer true or physical surface of the diaphragm must be equal to or smaller than the true surface of the cathode, and the inner true surface of the diaphragm must be equal to or less than true the surface of the anode, but smaller than the outer true surface of the diaphragm. This difference can be achieved both in the process of manufacturing the diaphragm, and by subsequent machining of its surfaces. This embodiment allows the efficient operation of the electrochemical cell when the pressure in the cathode chamber is higher than the pressure in the anode, i.e. under conditions when, simultaneously with the electrochemical treatment of water or a dilute aqueous solution of electrolytes, the filtration transfer of anions and some of the water from the cathode chamber to the anode takes place. The artificially increased true (physical) surface of the diaphragm facing the cathode allows, without a significant increase in filtration resistance, to retain the insoluble particles of heavy metal hydroxides formed in the cathode chamber, and thereby ensure long-term operation of the cell at a constant rate of filtration transfer of substances through the diaphragm.

The true surface of the diaphragm facing the anode is smaller than its true surface, which makes it easier to control the electromigration transfer of ions from the anode chamber to the cathode due to the increased concentration of cations in the surface layer of the diaphragm. The observed decrease in the intensity of the electromigration transfer of hydroxonium ions is very useful and occurs as a result of the suppression of the prototropic mechanism of migration of hydroxonium ions in the concentration polarization region on the filtering surface of the diaphragm. Under conditions of a deficit of “free” water molecules in the space charge region, the predominant electromigration transfer of metal cations occurs, which, in contrast to hydroxonium ions, has larger hydrated shells, which is significantly accelerated due to the electroosmotic transfer of water from the anode chamber to the cathode.

In the case of using concentrated solutions of electrolytes, the electroosmotic activity of the diaphragm decreases, but remains higher in comparison with ceramic diaphragms of aluminum oxide, boron oxide, zirconium oxide, asbestos.

The electroosmotic activity of the diaphragm is manifested by the ability to create a pressure drop in the chamber of a cell filled with fresh drinking water with a total salinity of 0.15-0.2 g / l due to an electric field of 15-30 V / cm and a magnitude of at least 1.5 kgf / cm ² . Smaller pressure drop values indicate either the irrational chemical composition of the diaphragm material or the excessively large size of the capillary channels in the diaphragm body.

The product of the interelectrode distance of the cell by the quotient of the sum of the true surfaces of the anode and cathode and the total volume of electrode chambers should be 3.9-4.1 for electrolyte solutions of various concentrations, which can conditionally be divided into two types: diluted and concentrated.

A similar, conditional separation of inorganic electrolyte solutions into dilute and concentrated is due to the fact that there is a fundamental difference between solutions whose concentration is more or less than 0.1 mol / L. Figure 4 shows the dependence (1) of the conductivity of aqueous solutions of various inorganic electrolytes - chlorides, sulfates, carbonates, nitrates of alkali metals, the corresponding acids and bases on their concentration in an aqueous solution. Dependence 2 characterizes the theoretically calculated distances between the centers of the electrolyte ions in the solution also depending on the concentration. A comparison of these dependences shows that with an increase in the concentration of electrolytes, a decrease in the distance between ions is observed, which, in accordance with theoretical concepts, is accompanied by an increase in the interaction between them. A concentration of about 0.1 mol / L is critical, which is manifested by a change in the slope of dependence 1. In the case of electrochemically activated solutions, the fastest mutual neutralization of the most highly active active substances occurs with a total concentration of electrolyte ions of more than 0.1 mol / L.

In dilute electrolyte solutions (less than 0.1 mol / L), small changes in the concentration of dissolved substances lead to significant shifts in the conductivity of the solution, which indicates the predominant role of the forces of interionic interaction in mass transfer processes and the low intensity of the processes of mutual neutralization of electrochemically activated antagonist substances.

In connection with the foregoing, a lower value of the aforementioned ratio (3.9) refers to cells for processing solutions with a concentration of less than 0.1 mol / l, and a larger value (4.1) refers to cells for processing solutions with a concentration of more than 0.1 mol / l Intermediate values are characteristic of cells through which electrolyte solutions flowing through the electrode chambers differ in concentration, but the total concentration of which (taking into account the volumetric flow rate) is close to 0.1 mol / L.

A decrease or increase in this ratio leads to an increase in energy consumption for the electrolysis process and a decrease in the yield of the target products due to a decrease in the mass transfer efficiency by microtoroid flows and the appearance of zones of preferential flow and zones of slow flow in the electrode chambers.

The ceramic diaphragm in the cell is made of grains of alumina surrounded by particles of zirconia partially stabilized by oxides of rare or rare earth metals and has the following composition: alumina - 60-90 wt.%, While at least 98% of the phase composition of alumina is in alpha form, zirconia - 10-40 wt.%, while at least 98% of the phase composition of zirconia is in tetragonal modification. To stabilize the tetragonal phase of zirconia, an additive is used - one or more oxides selected from the group consisting of yttrium, scandium, ytterbium, cerium, gadolinium oxides. The total amount of oxides is 1.0-10.0 wt.%. Subject to the above ratios, such a chemical composition of the material of the diaphragm and its physico-chemical properties ensure the sorption of highly charged metastable particles coming from the electrodes (figure 5). They do not penetrate deeply, since the energy of interaction with the heterogeneous hydrophilic surface of the material of the diaphragm is higher than the activation energy of electromigration migration, and therefore they are not mutually neutralized. In this regard, the electrochemical cell can be used as an electrochemical reactor with an ion-selective electroosmotic active diaphragm, providing selective ion transfer through the diaphragm by adjusting the pressure gradient across the diaphragm. In this case, the magnitude and direction of transfer is determined by the strength (density) of the current, the electric field strength in the diaphragm and the mineralization of aqueous solutions on both sides of it. The electrical resistance of the diaphragm with fully formed adsorption layers on its inner and outer surfaces is less than the resistance of the electrolyte filling the pores, and the mobility of ions in the pores is higher than the mobility of ions in a pure solution. The stationary equilibrium between the field strength in the diaphragm, due to the presence of adsorption layers of charged particles, is dynamic.

Such a diaphragm makes it possible to provide a modular electrochemical cell with the ability to work with the same efficiency in both laboratory and production conditions, as well as the ability to process both dilute aqueous solutions of electrolytes and concentrated aqueous-salt solutions, the properties of the diaphragm (its physicochemical composition and filtration ability) allow you to work in the mode when a concentrated electrolyte solution flows through one of the electrode chambers, and in the other forms a concentrated solution of the decomposition products of water and ions of one sort from this electrolyte (anions or cations), the selective migration of which is ensured by a combination of the physicochemical properties of the diaphragm and the electrophysical parameters of the cell (see Fig. 6).

The implementation of the ceramic diaphragm from grains of aluminum oxide, surrounded by particles of zirconium dioxide, partially stabilized by oxides of rare or rare earth metals, allows to increase its chemical resistance. The composition of the diaphragm is alumina - 60-90 wt.%, While at least 98% of the phase composition of alumina is in alpha form, zirconia is 10-40 wt.%, While at least 98% of the phase composition of zirconia is in tetragonal modification. To stabilize the tetragonal phase of zirconia, an additive is used - one or more oxides selected from the group consisting of yttrium, scandium, ytterbium, cerium, gadolinium oxides. The total amount of oxides is 1.0-10.0 wt.%. The specified composition provides mechanical resistance and the structure of the diaphragm. Changing the indicated intervals of the amount of ingredients leads to a significant decrease in the electroosmotic activity of the capillary-porous body of the diaphragm and a decrease in the adsorption-chemical activity of its surfaces facing the electrodes.

The total effect of the above patterns on indicators that determine the effectiveness of the electrochemical reactor is clearly shown in Fig.7. An assessment of the technical excellence of the claimed technical solution is shown using the diagram given in the book “Electrochemical systems in the synthesis of chemical products” (Fyoshin M.Ya., Smirnova MG - M .: Chemistry, 1985, p. 222, Fig. VII. 34). It can be seen from the diagram that the proposed technical solution far surpasses filter press electrolyzers, the interelectrode spaces of which are separated by a porous partition, and are very close to electrolyzers with fluidized electrodes in terms of the main indicators of technical perfection. Moreover, as follows from the angle of inclination of the region characterizing the proposed technical solution, electrochemical modular cells are significantly less sensitive to changes in the interelectrode distance and, consequently, the concentration of electrolytes in comparison with any other types of known electrochemical systems.

The organization of input into the cell of the processed electrolyte solution and output of electrolysis products may be different depending on the chemistry of the processes and the characteristics of the final electrolysis products. In general, this organization of flows is determined by the design of the attachment points, fixation and sealing points of the electrodes and the diaphragm, as well as devices for introducing electrolyte solutions into the electrode chambers and removing electrolysis products from the electrode chambers. These nodes, located on the end parts of the cell, can be made in the form of one or more parts of dielectric materials each. Depending on the requirements for the process occurring in the electrochemical cell, devices for supplying the treated solution to the electrode chambers can be connected to one node, and devices for removing electrolysis products to another. In this case, the movement of solutions in the electrode chambers is provided by direct flow. If it is necessary to carry out a countercurrent, each of the nodes will be connected to a device for supplying a solution to one electrode chamber and at the same time with a device for removing electrolysis products from another electrode chamber. Devices for supplying the treated solution to the electrode chambers and removal of electrolysis products from the electrode chambers can be made in the form of channels and nozzles combined with these parts, or in the form of holes and nozzles connected to the end parts of the electrodes. The length of the cathode and / or anode and / or diaphragm is determined by the cell designs and the conditions of its installation.

Units for mounting, fixing and fixing the electrodes and the diaphragm can also be made in the form of collectors equipped with channels for supplying and discharging electrolyte solutions and a sealing system. In this case, the anode and cathode must be made with holes that ensure the supply of electrolyte solutions to the electrode chambers and the removal of electrolysis products from the electrode chambers.

Brief Description of the Drawings

Figure 1 schematically shows the working chamber of the electrochemical cell in section.

Figure 2 presents a diagram showing the distribution of the lines of force of the current density and oxidation potential on the microroughnesses of the anode surface in dilute electrolyte solutions.

Figure 3 presents a schematic representation of the microtoroidal flow of solutions in the electrode chambers of the electrochemical cell.

Figure 4 presents a graph describing the dependence of the electrical conductivity of aqueous solutions of inorganic electrolytes and the average distance between the ions of these electrolytes, depending on the concentration.

Figure 5 presents a graph showing the change in the gradient of the potential in the interelectrode space of the electrochemical cell.

Figure 6 presents a diagram of ion-selective electrolysis in a cell with a diaphragm.

7 shows the dependence of the ratio of the area of the electrodes to the volume of the solution on the interelectrode distance in electrolyzers of various types.

On Fig shows some embodiments of the installation, mounting and fixing of the diaphragm and electrodes and devices for supplying and outputting electrolyte to the electrode chambers.

Figure 9 shows the scheme for producing electrochemically activated anolyte and catholyte fresh drinking water.

Figure 10 shows a diagram of experimental studies over time of the parameters of the electrochemically activated anolyte and catholyte of fresh drinking water in comparison with model solutions.

Figure 11 shows a comparison of pH and ORP values of drinking water during chemical and electrochemical regulation and the change in these parameters over time.

12-14 are diagrams of processes using the cell of the invention.

The working chamber of the electrochemical cell (figure 1) contains a cathode 1, a tubular anode 2 and a ceramic diaphragm 3, dividing the interelectrode space into the anode 4 and the cathode 5 of the chamber. The working chamber of the cell is characterized by the following dimensions: D ₁ and D ₂ - respectively, the inner and outer diameters of the anode made of a titanium pipe coated with rare metal oxides deposited on a developed outer surface; D ₃ and D ₄ - respectively, the inner and outer diameters of the ceramic permeable diaphragm; D ₅ and D ₆ - respectively, the inner and outer diameters of the cathode made of a titanium tube, the inner apparent (geometric) surface of which is close to the active true (physical) surface; L _ec is the length of the working part of the electrochemical cell.

On Fig shows the options for the installation of mounting and fixing the diaphragm and electrodes, as well as devices for supplying and discharging solutions of electrolytes.

In the cell, the attachment points of the electrodes and the diaphragm are made in the form of one or more parts of dielectric material each, and the devices for supplying and discharging the treated solution to and from the electrode chambers are made in the form of channels and nozzles combined with the parts of the units. Such an embodiment is shown in Fig. 8a, where nodes are located on the end parts of the electrochemical cell, which consist of two parts each, in which pipes and channels are made, communicating with one of the electrode chambers. The nodes also contain gaskets made of elastic material, providing sealing of the electrode chambers.

The nodes are made in the form of dielectric bushings located at the ends of the electrochemical cell, and grooves are made at the ends of the bushings, and the cell contains dielectric collector heads made with an axial channel, the heads being rotatable in the grooves of the bushings, while the diaphragm is fixed in the bushings with elastic gaskets located in the grooves of the bushings. The anode is fixed in the heads by means of elastic seals located in the axial channels of the heads, and channels are made in the heads and in the bushings, respectively, for supplying and discharging the treated water and / or solution, respectively, of the anode and cathode chambers. The channels are displayed on the side surfaces of the bushings and heads and are equipped with fittings.

When assembling nodes in the form of bushings and heads with channels, respectively, for introducing electrolyte into the electrode chambers and outputting electrolyte from the electrode chambers, the internal hollow electrode can be made with inlet and outlet nozzles communicating with its cavity and placed respectively at the ends of the hollow anode (Fig. .8b). This embodiment allows the coolant to flow through the hollow anode and, accordingly, reduce the cost of carrying out the electrochemical process by removing thermal disturbances. Such a cell can be used for processing low-concentrated solutions, upon receipt of disinfectant solutions of various chemical compositions with low total salt content. A cell using the cavity of the anode to pass the coolant can be used in the processes of water purification from nitrates.

In the cell, the attachment points of the electrodes and the diaphragm can be made in the form of one or more parts of dielectric material each, devices for supplying and discharging the processed solution of the cathode chamber are made in the form of channels and nozzles combined with the parts of the nodes. Devices for input and output of the treated solution of the anode chamber are made in the form of nozzles located at the end sections of the anode, while the anode is made with holes. Such an embodiment is shown in Fig. 8c, where the nodes are made in the form of three to four parts, including dielectric bushings, and gasket systems. In this case, the input and output nozzles of the cathode chamber are hermetically placed in the axial holes of the dielectric bushings, and the input and output channels communicating with the cathode chamber are respectively brought to the surface of the bushings.

A cell with such flow organization can be used in the processes of obtaining oxygen and hydrogen, as well as in the processes of producing sulfuric acid and sodium hydroxide from sulfate solutions.

The electrochemical cell for processing solutions can be made in such a way that the attachment points of the electrodes and the diaphragm are made in the form of one or more parts of dielectric material each, and the devices for input and output of the treated solution of the cathode chamber are made in the form of holes and nozzles located at the end sections cathode. Devices for supplying and outputting the treated solution of the anode chamber are made in the form of nozzles connected to the internal cavity of the anode, and holes are made in the end parts of the anode. Depending on the purpose, additional holes can be made in the anode body, evenly spaced along its length along the entire length of the working part of the cell. Such an embodiment is shown in FIG. 8d. In this case, the attachment points of the electrodes and the diaphragm also consist of three to four parts each and a gasket system. The inlet and outlet pipes of the anode chamber are made of electrically conductive material, mounted on the ends of the hollow anode, and communicate with its cavity. In this case, the hollow anode is made with perforations. On the surface of the cathode, in its end parts, holes are provided, equipped with nozzles that are input and output and communicating with the cathode chamber.

Such cells can be used in the processing of concentrated solutions of sodium chloride, for example, to obtain products of anodic oxidation from solutions of alkali metal chlorides.

Installation of all the structures shown in Fig. 8 is carried out on the protruding parts of the anode, equipped with means of tightening and fixing, such as nuts and washers.

The characteristic sizes and the aspect ratio of the structural elements of the working chamber of the modular electrochemical cell are shown in table 1.

Table 1 Parameter Name Formula or ratio The surface of the anode is geometric (S _ag ) S _ag = πD ₂ L _ec Geometrical cathode surface (S _cg ) S _cg = πD ₅ L _ec The ratio of the true (physical) surface areas of the anode (S _af ) and cathode (S _cf ) S _af : S _cf ≥1
(S _af ≥S _cf ) The external surface of the diaphragm is geometric (S _dcg ) S _dcg = πD ₄ L _ec The ratio of the true (physical) surface of the cathode (S _cf ) and the true (physical) outer surface of the diaphragm (S _dcf ) S _cf : S _dcf ≥1
(S _cf ≥S _dcf ) The inner surface of the diaphragm is geometric (S _dag ) S _dag = πD ₃ L _ec The ratio of the true (physical) inner surface of the diaphragm (S _daf ) and the true (physical) surface of the anode (S _af ) S _af : S _daf > 1
(S _af > S _daf ) Interelectrode Distance (IED) IED = (D ₅ -D ₂ ): 2 Cross sectional area of the cathode chamber (S _c ) S _c = 0.785 (D ₅ ² -D ₄ ² ) Cross sectional area of the anode chamber (S _a ) S _a = 0.785 (D ₃ ² -D ₂ ² ) The diaphragm cross-sectional area (S _d ) S _d = 0.785 (D ₄ ² -D ₃ ² ) The volume of the anode chamber (V _a ) V _a = S _a L _ec The volume of the cathode chamber (V _c ) V _c = S _c L _ec The ratio of the cross-sectional areas of the electrode chambers (S _c , S _a ) and the diaphragm (S _d ) 0.8≤S _c : (S _a + S _d ) ≤1.0 The relationship between the interelectrode distance (IED), the areas of the true surface of the anode (S _af ), the cathode (S _cf ) and the volumes of the anode (V _a ) and cathode (V _c ) electrode chambers 3.9≤IED [(S _af + S _cf ) :( V _a + V _c )] ≤4.1 The relationship between the true (physical) surfaces of the anode (S _af ), the cathode (S _cf ), the outer (S _dcf ) and the inner (S _daf ) true (physical) surfaces of the diaphragm S _af ≥S _cf ≥S _dcf ≥S _daf

The cell works as follows. Through devices for supplying an electrolyte solution (not shown in FIG. 1), the treated solution is supplied to the anode 4 and cathode 5 of the cell chamber. Depending on the chemistry of the process, the movement of the electrolyte to the chambers is carried out in a parallel flow - from bottom to top or top to bottom or countercurrent. A variant is possible in which the filling of one of the electrode chambers occurs due to electrofiltration through the diaphragm from another chamber or due to filtration under the influence of the differential pressure across the diaphragm. After the passage of the electrode chambers, the electrolyte through the output devices (not shown in FIG. 1) is withdrawn from the cell. Processing the solution is carried out either with a single flow through the chambers 4 and 5, or in the case of the anode 2 with holes - when the solution is circulated in the anode chamber.

Embodiments of the invention

The invention is illustrated by the following examples, which, however, do not exhaust all the possibilities of implementing the invention. In the examples, depending on the conditions of the problem being solved, electrochemical cells were used, the length of the working part of which was 180-300 mm, the interelectrode distance was 3-11 mm, and the thickness of the diaphragm was 0.7-2.8 mm. Table 2 shows the cell parameters that were used in the implementation of examples of the use of the present invention. In the examples, the number of the cell that was used in each case is indicated.

table 2 The dimensions of the working part of the electrochemical modular cells used in the technological processes described in the examples of practical implementation Options Numbers of electrochemical modular cells one 2 3 four 5 D ₁ mm 14.0 10.5 9.5 7.7 6.0 D ₂ mm 16,0 14.0 12.0 10,2 8.0 D ₃ mm 23.0 19.5 16,0 12.5 9.5 D ₄ mm 28.0 24.0 19.2 15,5 11.5 D ₅ mm 36.0 30,0 24.0 18.7 14.0 D ₆ mm 40,0 33.7 27.5 21.7 16,0 L _ec , mm 290.0 265.0 240.0 210.0 185.0 IED mm 10.0 8.0 6.0 4.2 3.0 S _c , mm ² 402 254 163 86 fifty S _a , mm ² 214 97 88 41 20.6 S _d mm ² 200 153 88 66 33 V _a , mm ³ 62060 25705 21120 8610 3811 V _c , mm ³ 116580 67310 39120 18060 9259 S _c : (S _a + S _d ) 0.97 1,0 0.93 0.8 0.93 IED [(S _af + S _cf ) :( V _a + V _c )] 3.91 4.05 3.95 4.08 3.93

Example 1. Obtaining electrochemically activated anolyte and catholyte from fresh water. In the example, an electrochemical cell No. 5 with an uncooled anode was used (see table 2 and figa).

Tap drinking water with a total salinity of 0.22 g / l and initial pH values of 7.1 and φ = + 280 mV (HSE) was subjected to anodic and cathodic treatment in the indicated electrochemical modular cell. Upon receipt of the anolyte according to the scheme depicted in Fig. 9, the pressure in the anode chamber was 0.7-0.8 kgf / cm ² , which was 0.3-0.4 kgf / cm ² higher than the pressure in the cathode chamber. The volumetric flow rate of anolyte was in the range of 5-6 l / h, catholyte - 10-12 l / h. Upon receipt of catholyte, the pressure in the cathode chamber was 0.8-0.9 kgf / cm ² and exceeded the pressure in the anode chamber by 0.4-0.5 kgf / cm ² . The volumetric flow rate of catholyte was in the range of 6-7 l / h, anolyte - 10-12 l / h. The regulation of the above hydraulic characteristics was carried out using variable hydraulic resistances at the inlet to the cell’s electrode chambers and pressure regulators "to themselves" at the outlet of the electrode chambers (not shown in the diagram). The specific cost of the amount of electricity in the treatment of water was about 1000 coulomb per liter (C / l).

The experimental design is shown in FIG. 10. Number 1 indicates the source of drinking water, the parameters of which were subjected to chemical and electrochemical regulation. The pH and ORP (φ) values of the anolyte and catholyte of drinking water were measured immediately after receipt (sample numbers 2 and 3 in FIG. 10). The pH meter-millivoltmeter I-120 was used.

Typically, as a result of cathodic treatment, fresh or weakly mineralized water acquires an alkaline reaction due to the conversion of some of the dissolved salts to hydroxides. Its redox potential (ORP) sharply decreases, surface tension decreases, the content of dissolved oxygen and nitrogen decreases, the concentration of hydrogen, free hydroxyl groups increases, the electrical conductivity decreases, and the structure of not only ion hydration shells, but also the free volume of water changes.

As a result of the formation of readily soluble sodium and potassium hydroxides and an increase in pH, a shift in carbon dioxide equilibrium occurs with the formation of sparingly soluble calcium and magnesium carbonates from the usually soluble compounds of these metals (bicarbonates, chlorides, sulfates) in the source water. Heavy metal and iron ions turn into insoluble hydroxides.

During anodic electrochemical treatment, the acidity of water increases, the redox potential increases due to the formation of stable and unstable acids (sulfuric, hydrochloric, hypochlorous, supra sulfuric), as well as hydrogen peroxide, peroxosulphates, peroxocarbonates, oxygen-containing chlorine compounds and various intermediate compounds that occur during spontaneous decomposition and interactions of these substances. Also, as a result of anodic electrochemical treatment, the surface tension slightly decreases, the electrical conductivity increases, the content of dissolved chlorine, oxygen increases, the concentration of hydrogen, nitrogen decreases, and the structure of water changes.

A quantitative characteristic of the acidity or alkalinity of water is a hydrogen pH, which is determined by the activity of hydrogen ions (α _{H +} ) or, in other words, by the ratio of the concentration of hydroxonium ions H ₃ O ⁺ and hydroxyl OH ^- .

The redox potential (ORP or, in other words, φ) is another important parameter, since it characterizes the activity of electrons in an aqueous solution (water). It is measured using a high-resistance millivoltmeter and a pair of electrodes, one of which is a reference electrode (auxiliary), and the other is a measuring one. In practical measurements, the most commonly used silver chloride electrode (HSE) as an auxiliary and platinum in the role of the measuring one. The platinum measuring electrode exchanges with the solution only electrons crossing the electrode – solution boundary, i.e. Ideally, it can be considered as a reservoir with electrons. When such an electrode is immersed in a solution (water), a contact occurs between two phases that have a common particle - an electron, therefore, the equilibrium condition for the electrode-solution interface is characterized by the equality of the electrochemical potentials of the electrons in the electrode and the solution.

There is a relationship between ORP and pH, which is practically expressed in the fact that when the pH of drinking water is changed by 1 unit by the addition of sodium hydroxide or hydrochloric acid, the ORP changes accordingly by approximately 59 mV - it increases with decreasing pH and decreases with its increase. From the dependence of the potential of the inert electrode (the oxidation potential of the solution) on the activity of solvated electrons in the solution, which is established on the basis of fundamental laws discovered by Nernst, it follows that the increase in the oxidation potential φ is due to a decrease in the activity of electrons in the solution and, conversely, a decrease in φ is determined by an increase in the activity of electrons .

The nature of the ORP is primarily due to the quantum-mechanical characteristics of the atoms of the elementary electrochemical system ("electrode - solution"), the peculiarities of its electronic structure, which determine the ionization potentials of the elements. The electronic structures of atoms and ions also largely determine the nature and energy of ion hydration processes.

In the electrochemical unipolar water treatment, the pH and ORP values of catholyte and anolyte of drinking water go far not only beyond the scope of chemical regulation, but also beyond the thermodynamic stability of water limited by the potentials of hydrogen and oxygen electrodes: φ _{H2 (НВЭ)} = -0.059 pH and φ _{O2 (NVE)} = 1.23-0.059 pH, where NVE is the normal hydrogen reference electrode. The lower the salinity of the water, the more difficult it is to achieve the maximum possible pH and ORP values of catholyte and anolyte. The decisive influence is exerted by the structural and electrochemical features of the reactor, as well as the technology of the electrochemical processing process itself. Experimental studies of the results of electrochemical activation of drinking water in comparison with chemical control data for the parameters of the same water are described below.

Hydrochloric acid and sodium hydroxide were introduced into the starting tap water to obtain analogues (in pH value) of anolyte and catholyte (sample numbers 4 and 5, Fig. 10). The pH and φ of chemical analogues were measured, and, using the Nernst equation, the values of φ corresponding to the measured pH values for all samples were calculated. These data are given for samples 2-5 as φ _theory . PH and φ measurements for all four samples were repeated after 24 and 168 hours of storage (numbers 6–9 and 10–13, respectively). An analysis of the experimental results for each of the test samples is shown in the diagram numbered 14-17. The same data are shown graphically in Fig. 11 in pH - ORP coordinates in the form of trajectories of changes in water parameters during chemical and electrochemical regulation, concluded between the lower and upper boundaries of the thermodynamic stability of water - the potentials of hydrogen and oxygen electrodes.

In Fig. 11, the numbers of points on the lines correspond to the numbers in the experimental design (Fig. 10). As can be seen from the data presented, for anolyte and catholyte there are significant relaxation changes in pH and φ, while for their chemical models there are no such changes. For chemical models of anolyte and catholyte (numbers 4 and 5, Figs. 10, 11), almost complete coincidence of the measured and theoretically calculated values of φ is observed. For activated anolyte and catholyte (numbers 2 and 3), these differences are more than 700 mV.

In addition, another possibility of change was investigated (p chemical models of anolyte and catholyte in order to achieve the same values as in water, after electrochemical exposure. To do this, oxygen was bubbled through water with the addition of hydrochloric acid (4) at a ratio of 100 liters of gas per 1 liter of water. An increase in the redox potential of 100 mV, i.e., up to +690 mV, was achieved. Sparging of hydrogen in the same ratio (100 liters of gas per 1 liter of water) through water with the addition of sodium hydroxide (5)to reduce φ to - 300 mV, that is, 320 mV. Thus, chemically, it was not possible to achieve the same pH and φ parameters that were obtained during electrochemical exposure.

It is characteristic that an increase in the mineralization of the initial water decreases the magnitude of the relaxation changes in the pH and φ parameters. The most pronounced relaxation processes are manifested in the electrochemical treatment of water with a salinity of 0.1 to 1 g / l.

Relaxation in accordance with the classical definition of thermodynamics is a gradual transition of a system (a certain volume of water or an aqueous solution of an electrolyte) from a nonequilibrium state caused by external influence to a state of thermodynamic equilibrium. Relaxation is an irreversible process and therefore, by virtue of the law of increasing entropy, it is necessarily accompanied by the transition of part of the internal energy into heat: energy dissipation. Like any nonequilibrium phenomenon, relaxation is not determined solely by thermodynamic characteristics (for example, pressure, temperature), but significantly depends on microscopic characteristics, in particular, on parameters characterizing the interaction between particles. The establishment of equilibrium usually occurs in two stages. At the first stage, equilibrium is established only in individual microvolumes of water or solution. At the second stage, slow relaxation processes occur, as a result of which the physicochemical parameters reach stationary values determined by the conditions of equilibrium with the environment. Slow processes are associated with a very large number of successive collisions of particles with each other. Their relaxation time is proportional to the size of the system (the volume of electrochemically activated water). Slow relaxation processes include phenomena such as viscosity, diffusion, thermal conductivity, electrical conductivity, catalytic activity, redox equilibrium, pH, surface tension, etc. The nature of the rapid relaxation process is determined by the microscopic details of the interaction between the particles. The specificity of the interaction can lead to the fact that the process of establishing equilibrium for any microscopic parameter will be greatly slowed down in comparison with the same processes for other parameters. The relaxation rate is determined by the time during which the measured characteristic of the system changes e times compared with the initial value.

The rate and magnitude of relaxation changes in a parameter is usually the higher, the more effective is the process of electrochemical activation itself, i.e. the less time is spent on the electrochemical effect, the less energy is spent on heat generation, the more, respectively, the energy is spent on physicochemical water transformations, the more microvolumes of water are in contact with the double electric layer (DES) of the electrode, in where the electric field reaches several million volts per centimeter, the higher the degree of unipolarity of the impact, i.e. the lower the intensity of penetration into the electrode space of electrochemically active particles from the electrode space of the opposite in charge sign of the electrode.

Example 2. Inversion of sugar syrup into glucose-fructose syrup. In this example, we used one electrochemical modular cell No. 5 with a cooled anode (see table 2), the ratio of the physical surfaces of the anode to the cathode (S _af : S _cf ) was 1.02.

Invert sugar syrup into glucose-fructose is carried out in order to save 20-30% of sugar used in the confectionery industry, as well as in the production of soft drinks, juices, ice cream. Products containing glucose-fructose instead of sugar syrup have a beneficial effect on the health of people with diabetes, and also have longer shelf life without loss of freshness. One of the common methods of inversion is the acidification of sugar syrup with any inorganic acid, such as hydrochloric acid, to a pH of 2.0-2.5, followed by heating and holding at elevated temperature. The sucrose inversion reaction is bimolecular, one sugar molecule and one water molecule participate in it. In aqueous solutions of sucrose, the amount of water during this reaction changes little, because only a small part of it reacts. During the inversion reaction, which proceeds at an elevated temperature (about 75 ° C) for 30-40 minutes, the amount of sucrose decreases as a result of its irreversible conversion to glucose and fructose. After the reaction is completed, a neutralizing agent, for example sodium hydroxide, is added to the syrup, bringing its pH to values close to neutral. Then the syrup is filtered to remove colloidal suspensions, however, it is not possible to remove the salt resulting from the use of chemical agents. The electrochemical method of pH regulation allows the inversion of sugar syrup without the use of chemicals.

The process was carried out as follows.

Sugar syrup with a concentration of 67% was fed from a 5-liter container using a peristaltic pump into the anode chamber of the cell at a speed of 1.0 l / h. Sugar syrup was pumped through the cathode chamber of the cell, included in a circulation circuit consisting of a 1 liter container with the same syrup and another peristaltic pump, at a speed of 1.0 liter per hour. The cell anode was cooled with running tap water flowing at a rate of 1.0 liter per hour. A current of 0.4 ampere at a voltage of 100 volts was passed through the cell. In the anode chamber of the cell using a pressure stabilizer installed on the line of syrup exit from the anode chamber, an excess pressure of 0.5 kgf / cm ^{2 was created} in comparison with the pressure in the cathode chamber. At this pressure drop, experiments showed that hydroxyl ions from the cathode chamber could not enter the anode chamber, reducing the efficiency of the electrochemical process. The pH of the syrup was measured at the inlet and outlet of the anode chamber. The pH values were 7.2 and 2.3, respectively. The syrup obtained after the anode treatment was heated in a container at a temperature of 75 ° C for 20, 30 and 40 minutes. Then, after cooling, the resulting syrup with a low pH was passed through the cathode chamber of the cell with a peristaltic pump at a rate of 0.7 l / h. The anode chamber of the cell was included in the circulation circuit, which consisted of a 1 liter container with syrup previously subjected to cathodic treatment, and another peristaltic pump, which pumped the auxiliary volume of the syrup in the forward flow mode at a speed of 1.0 l / h. During cathodic processing of the bulk of the syrup, the pressure drop between the electrode chambers was maintained at 0.6 kgf / cm ² using a pressure stabilizer at the exit of the cathode chamber. The pH of the obtained invert solution after cathodic treatment was 5.6, which corresponds to the requirements of an industrial process. The degree of sugar inversion, depending on the exposure time at elevated temperature (20, 30, and 40 minutes), was 30, 55, and 80%, respectively.

When using a cell with a ratio of the physical surface area of the anode to the physical surface area of the cathode less than unity, namely 0.57, the pH of the syrup after exiting the anode chamber was 3.5. The degree of sugar inversion in this case, depending on the exposure time at elevated temperature (20, 30 and 40 minutes) was 15, 30 and 50%, respectively.

Example 3. The deoxidation of milk. For use in this technology, an electrochemical modular cell No. 4 was used (see Table 2)

One of the main factors causing a rapid change in the properties and sensory quality of milk is its acidity. The acidity of milk is due to hydrogen ions formed as a result of electrolytic dissociation of acids and acid salts contained in milk. Hydrogen ions are very active, destroying the casein-calcium phosphate complex, secrete casein, curdle milk and affect its salt component. With increasing acidity, the properties of milk, both a food product and raw materials for processing, gradually change. In quantitative accounting, the acidity of milk is usually expressed in degrees Turner (° T). The acidity of freshly milked milk averages 16-18 ° T. The pH value of such milk is in the range of 6.3-6.8. With the growth of lactic acid bacteria in milk, lactic acid appears, which gradually removes calcium from casein, the pH of milk decreases and the colloidal system of the casein complex becomes less stable. Milk with an acidity above 22 ° T boiling, as a rule, does not withstand and coagulates. In industrial conditions, such milk can only be used for the preparation of cottage cheese. Deoxidation of milk is a process of normalization (reduction) of its acidity. It is possible to change the acidity of milk by introducing an alkaline reagent, such as drinking soda. However, the method of chemical regulation of the acidity of milk inevitably leads to an increase in its mineralization and, as a result, to a decrease in stability during boiling and loss of taste quality indicators. It is possible to electrochemically change the acidity of milk without resorting to chemicals. A schematic diagram explaining the studies performed is shown in Fig. 12.

The object of the study was fresh and pasteurized cow's milk with a fat mass fraction of 3.2%, which has a different acidity: 28 and 32 ° T.

Milk from a container of 5 liters was fed into the cathode chamber of the cell at a speed of 5 l / h. Through the anode chamber of the cell, countercurrent flow of tap drinking water was carried out at a rate of 7 liters per hour. An increased pressure (0.7 kgf / cm ² ) was created in the cathode chamber compared to atmospheric pressure in the anode chamber using a pressure stabilizer installed at the exit of the cathode chamber. A current of 2.8 A at a voltage of 25 volts was passed through the cell. With this mode of operation, the acidity of milk decreased from 28 to 16 ° T and from 32 to 18 ° T.

The organoleptic analysis of deoxidized milk testified to the elimination of defects of sensory quality during electrochemical processing.

Example 4. The regeneration of oxidized fats. For use in this technology, an electrochemical modular cell No. 3 was used (see Table 2).

The technology for the regeneration of oxidized fats is based on the cathodic reduction of products of fat oxidation during the flow of fat heated to 60-70 ° C through the cathode chamber of an electrochemical reactor. In this case, ordinary drinking water flows through the anode chamber of the electrochemical reactor, heated to the same temperature as fat. A necessary condition for processing is the fullest possible contact of all microvolumes of the processed fat with the cathode surface, as well as increased pressure in the cathode chamber in comparison with the pressure in the anode: the pressure drop across the diaphragm should be at least 0.3-0.5 kgf / cm ² .

A melted yellowish-gray cooking oil with an acid number of 0.96 mg KOH / g, with a pungent, unpleasant odor and rancid taste, having a temperature of 65 ° C, was fed from a 10-liter container with a peristaltic pump to the entrance to the cathode chamber of a vertically installed cell with speed of 3 l / h. Hot tap water with a temperature of about 70 ° C at a speed of 4 l / h was also fed to the inlet of the anode chamber also in the lower part of the cell in the forward flow mode.

Using a pressure stabilizer installed at the exit of the cathode chamber, the pressure drop across the diaphragm was 0.9 kgf / cm ² .

Analysis of fat after cathodic treatment showed that its acid number decreased to 0.35 mg KOH / g. The processed fat had a light yellow color, a clean taste, had no smell, and its storage stability reached 3 months at room temperature. Thus, it was found that the cathodic treatment of fat allowed to completely restore the lost properties and reduce its ability to oxidize during storage.

Example 5. The synthesis of peroxocarbonate disinfectant solution. Electrochemical cell No. 5 (see table 2) was used to obtain peroxocarbonate solution.

Cylindrical tubular electrodes with a 0.7 mm thick ceramic diaphragm separating them are coaxially mounted in the cell. Ceramic composition: aluminum oxide - 80%, modified zirconia - 15%. Modified zirconia contains 5.0% yttrium oxide. The electrodes used were titanium coated with iridium oxide (anode) and titanium with a pyrocarbon coating (cathode). The length of the cell’s working chamber is 185 mm, the volume of the cathode electrode chamber is 10 ml, and the anode electrode chamber is 7 ml.

The experimental setup works as follows. Fresh water at a rate of 3 liters per hour enters the entrance to the cathode chamber, the output of which is directed to the drainage. An initial solution of an alkali metal carbonate concentration of 0.5 g / l is supplied to the inlet of the anode chamber in a countercurrent manner using a metering pump at a speed of 1 l / h. At the output of the anode chamber, a pressure regulator is installed, which allows you to maintain a differential pressure of 0.2 kgf / cm ² on the diaphragm. A stabilized current of 2 A flows through the cell, while the voltage at the electrodes is in the range of 25-30 volts. At the cathode, a water reduction reaction takes place:

2Н ₂ O + 2е → Н ₂ + 2ОН ^- .

As water moves in the cathode chamber, the concentration of sodium hydroxide in it increases as a result of the electromigration of sodium ions from the anode chamber through the diaphragm to the cathode chamber.

In the anode chamber at the initial stage of the flow of the sodium carbonate solution, there are reactions of the formation of sodium peroxocarbonates in accordance with the total electrochemical reactions:

2Na ₂ CO ₃ + 10H ₂ O → 2HOC (O) OOC (O) ONa + 2NaOH + O ₂ + 8H ₂ ;

2Na ₂ CO ₃ + 6H ₂ O → 2HOC (O) OONa + 2NaOH + 4H ₂ + CO ₂ ;

With the further advancement of the carbonate solution in the anode chamber and a decrease in the pH of the medium, it is depleted of sodium ions and carbonates turn into hydrocarbonates, which also undergo oxidation by the following total reactions:

2NanSO ₃ + 2H ₂ O → HOC (O) OOC (O) ONa + NaOH + 2H ₂ + 1 / 2O ₂ ;

2NaHCO ₃ + H ₂ O → HOC (O) OONa + NaOH + H ₂ + CO ₂ .

With a further decrease in pH in the anode chamber and its approximation to pH 7, the next step in the anodic oxidation of sodium peroxocarbonate solutions is the conversion of peroxocarbonate salts to the corresponding acids - sub-curved (LOC (O) OOS (O) OH) and mono-angled (LOC (O) UN):

HOC (O) OOC (O) ONa + H ₂ O → HOC (O) OOC (O) OH + NaOH;

HOC (O) OONa + H ₂ O → NOS (O) UN + NaOH.

The resulting solution - an anolyte "Perox" has the following characteristics: the content of mono-angular and diacitric acids - from 20 to 50 mg / l, the redox potential - in the range from +500 to +800 mV relative to the silver chloride reference electrode.

Example 6. The synthesis of a low saline disinfectant solution (neutral anolyte AN) with a high specific content of chlorine-oxygen and hydroperoxide oxidants. The electrochemical cell No. 5 (see table 2) according to the invention was used for the synthesis of a low saline solution with a high specific content of oxidants.

Drinking water was supplied to the anode chamber of the cell at a rate of 3 l / h. The total salinity of the water was 0.15 g / l. The pressure stabilizer installed at the outlet of the anode chamber provided a constant pressure in the anode chamber of 1.2 kgf / cm ² . The inlet and outlet of the cathode chamber were connected by flexible hoses with a circulation capacity of 0.2 liters, also filled with drinking water and placed at a level 10 centimeters above the vertically mounted cell. When a voltage of 40 volts was applied to the cell from a constant current source of direct current, the current strength, gradually increasing from the initial value of 0.8 A, reached a value of 3 A. At the same time, catholyte circulated in the cell’s cathode chamber due to the gas lift working due to the released hydrogen . The oxidant content in the water obtained as a result of the anodic treatment in the cell, measured by the titrimetric method, was 50 mg / L.

When using cell No. 5 with a ratio of the physical area of the anode to the physical area of the cathode equal to 0.63, the oxidant content in the water obtained as a result of the anode treatment in the cell, measured by the titrimetric method, was 24 mg / L.

Example 7. Water purification from anionic surfactants (AAS). An electrochemical cell No. 3 (see Table 2) with a cooled anode was used to remove anionic surfactants from the water (AAS). Using a peristaltic pump at a speed of 12 liters per hour, purified water was pumped through the anode chamber of the cell in a circulation mode, the volume of which in the tank was 9 liters. An auxiliary electrolyte solution, the volume of which in the tank was 1 liter, was also pumped through the cathode chamber of the cell using a peristaltic pump also in circulation mode at a speed of 15 l / h. A flow of cooling water was carried out through the anode cavity at a rate of 5 liters per hour.

After the circulation mode was established, a constant voltage from a stabilized power supply was applied to the cell electrodes.

The circulating anolyte was periodically analyzed for the content of anionic surfactants (AAS) by a spectrophotometric method using methylene blue. Based on the results of the analyzes, the values of the degree of removal of APAW from the solution, the specific amount of electricity (Qe) and the specific energy consumption (We) for the removal (decomposition) of 1 gram of APAW were calculated according to the formulas:

Qe = I × t / m; We = U × I × t / m, where m is the mass of decomposed matter, g; I is the current strength, A; U is the voltage, V; t - process time, hour.

During the experiment, constant levels of solutions in the tanks of circulating purified water and catholyte were maintained by changing the circulation rate of the solutions and using pressure stabilizers at the outlet of the electrode chambers.

As the purified water (anolyte), a model solution was used, which was prepared by introducing r. Moscow synthetic detergent "Lotus-automatic" to achieve a concentration of ACAS 50 mg / l and sodium chloride in an amount of 1.5 g / l. A 1.0 mol / L sodium hydroxide solution was used as catholyte. Throughout the process, the pH value in the circulating anolyte was maintained at a level of 6-8 by adding a 6 M sodium hydroxide solution. The experiment was carried out at a constant current strength of 16 A, the voltage at the electrodes was 9.0–9.5 V. The results of the removal of ACAS from the model solution are shown in Table 3.

Table 3 The values of the degree of removal of ACAS from the model solution, specific amount of electricity (Qe), specific consumption of electricity (We) Process time, hour 0 one 2 7 9 eleven APA concentration, mg / l 50,0 23.8 17.6 6.9 3.3 2.1 The degree of removal of surfactants,% 0 52,4 64.8 86.2 93,4 95.8 Qe, A × hour / g 0 244 395 1039 1233 1470 We, W × h / g 0 2321 3753 9875 11717 13962

The results presented in the table show that in 11 hours it is possible to almost completely remove the surfactant from 9 liters of the model solution. The values of the specific amount of electricity (Qe) and the specific energy consumption (We) for removing 1 gram of APAW continuously increase as the concentration of APAW decreases and are 244 A × h / g and 2321 W × h / g, respectively, at the beginning of the process and 1470 A × hour / g and 13960 W × hour / g - at the end of the process.

Thus, the experiments showed that it is possible in principle to use the electrochemical method to remove ACAS from solutions. Similar results were also obtained on a block of 8 cells No. 5 (see Table 2), the anodes of which did not cool during operation and the current through each of which was 2 A.

Example 8. Purification of water from nitrates. The electrochemical cell No. 2 (see table 2) according to the invention was used to purify water from nitrates.

The tests were carried out in a laboratory setup consisting of a single cell, a direct current source that allows you to regulate and maintain voltage and current in the range of 0-30 volts and 0-3 amperes, respectively, a peristaltic pump and tanks for circulating anolyte and catholyte.

The test procedure was as follows: the treated water containing dissolved nitrates was pumped using a pump in the circulation mode, first through the cathode chamber of the cell, and then through the anode chamber in countercurrent mode. Circulating water was periodically analyzed for ammonia by a spectrophotometric method using the Nessler reagent. A model solution prepared by adding ammonium sulfate solution to tap water to achieve an ammonium ion concentration of 145-185 mg / L, pH 7.6-7.8 was used as purified water. In some cases, sodium chloride was added to the solution in an amount of 1-3 g / l. Based on the analysis results, the degree of ammonia removal from water, the specific amount of electricity (Qe) and the specific energy consumption (We) for removing (decomposing) 1 gram of ammonia, as well as the current efficiency value (CAP) were calculated according to the formulas: Qe = I × t / m; We = U × I × t / m; VPT = m × F / (I × t × E) × 100%, where m is the mass of decomposed matter, g; I is the current strength, A; U is the voltage, V; t is the process time, hour; F - Faraday constant (F = 26.8 A × hour); E is the electrochemical equivalent (E for ammonia is 5.7 g).

The chemical processes of water purification from nitrates are as follows. In the electrochemical cell, the total decomposition of sodium chloride proceeds with the release of molecular chlorine in the anode chamber and the formation of sodium hydroxide in the cathode chamber:

2NaCl + 2Н ₂ O-2е → 2NaOH + H ₂ + Cl ₂

The total reaction of ammonia removal in the anode chamber is described by the equation:

2NH ₃ + 3Cl ₂ + 6NaOH = N ₂ + 6H ₂ O + 6NaCl,

from which it follows that when ammonia is destroyed by chemically or electrochemically produced gaseous chlorine, the amount of chloride ions generated will be the same - 3 g chloride ion per 1 mol of ammonia or 6.3 g chloride ions per 1 g of ammonia.

The advantage of the electrochemical treatment of ammonia-containing solutions, especially with a high concentration of ammonia, is the possibility of complete destruction of ammonia by adding relatively small amounts of chloride ions (1-2 g / l), which are practically electron carriers and are not consumed during the reaction.

The experiment was carried out with simultaneous circulation of the purified solution through the cathode, and then through the anode chamber. The volume of the solution is 3.8 liters. The circulation speed of the solution is 30 l / h. During the experiment, a constant current strength of 2.5 A was maintained, while the voltage on the cell was 20-22 V. The pH value of the solution was maintained in the range of 6-8. The results are shown in table 4.

Table 4 The values of the degree of removal of ammonia, specific amount of electricity (Qe), specific consumption of electricity (We) and current efficiency (VPT) Process time, hour 0 one 2 3 four 5 The concentration of ammonia, mg / l 184 174 169 151 149 136 The degree of removal of ammonia,% 0 5,4 8.2 17.9 19.0 26.1 Qe, A × hour / g 0 66 88 60 75 68 We, W × h / g 0 1428 1850 1244 1571 1398 VPT,% 0 6.8 5.1 7.5 5.9 6.5

The results presented in the table show that after 5 hours of the process only 26% of ammonia is removed from the solution, while there is a high energy consumption for the decomposition of ammonia, and the VPT value does not exceed 7.5%, due to the low efficiency of ammonia oxidation by anodic electrolysis products (atomic and gaseous oxygen, hydrogen peroxide, etc.). In this regard, all further experiments were carried out after adding sodium chloride to the solution being purified.

The next experiment was carried out similarly to the previous one, with the difference that 1 g / L of sodium chloride was added to the initial solution. The volume of the solution is 3.8 liters. The circulation speed of the solution is 30 l / h. During the experiment, a constant current strength of 3.0 A was maintained, while the voltage on the cell was about 10 V. The pH value of the solution was maintained in the range of 6-8. The results are shown in table 5.

Table 5 The values of the degree of removal of ammonia, specific amount of electricity (Qe), specific consumption of electricity (We) and current efficiency (VPT) Process time, hour 0 one 2 3 four 5 6 7 The concentration of ammonia, mg / l 155 133 107 88 70 23 3.0 0 The degree of removal of ammonia,% 0 14.2 31,0 43,2 54.8 85,2 98.1 one hundred Qe, A × hour / g 0 36 33 35 37 thirty 31 36 We, W × h / g 0 502 362 354 372 299 312 312 VPT,% 0 12,4 13.6 12.6 12.0 14.9 14.3 12.3

Further studies were carried out similarly, with the difference that 3 g / L of sodium chloride was added to the initial solution. The volume of the solution is 3.8 liters. The circulation speed of the solution is 30 l / h. During the experiment, a constant current strength of 3.0 A was maintained, while the voltage on the cell was about 7 V. The pH value of the solution was maintained in the range of 6-8. The results are shown in table 6.

Table 6 The values of the degree of removal of ammonia, specific amount of electricity (Qe), specific consumption of electricity (We) and current efficiency (VPT) Process time, hour 0 one 2 3 four The concentration of ammonia, mg / l 135 one hundred 56 twenty 0 The degree of removal of ammonia,% 0 25.9 58.5 85,2 100.0 Qe, A × hour / g 0 22.5 20,0 20.6 23,4 We, W × h / g 0,0 167 140 144 164 VPT,% 0,0 19.8 22.3 21.7 19.1

The results presented in the tables show that adding sodium chloride to the solution in an amount of 1-3 g / l allows ammonia to be completely removed in 4-7 hours due to its oxidation by the products of anodic oxidation of chloride ions (chlorine gas, hypochlorite ion, etc.) .

Thus, the experiments showed that for the effective removal of ammonia from solutions by electrochemical oxidation using a flowing modular electrochemical cell, it is necessary to add sodium chloride in the amount of 1-3 g / l to the treated solution, and the process should be carried out while the solution is circulating through the cathode and anode chamber.

Example 9. Obtaining sulfuric acid, hydrogen and sodium hydroxide from a solution of sodium sulfate. The specified method was implemented using cell No. 1 (see table 2 and fig.8d). A schematic diagram of the implementation of the method is shown in Fig.13. A solution of sodium sulfate with a concentration of 100 g / L was dosed at a rate of 0.25 L / h into the anode chamber of the cell. Fresh water was introduced into the cathode chamber at a rate of 0.6 l / h. The pressure in the anode chamber exceeded the pressure in the cathode chamber by 0.4 kgf / cm ² . Under the influence of an electric current with a force of 25 to 35 A flowing through the cell, sodium ions from the anode chamber migrate to the cathode chamber, forming sodium hydroxide. The total electrochemical reaction is described by the following equation:

Na ₂ SO ₄ + 4H ₂ O → 2NaOH + H ₂ SO ₄ + 2H ₂ + O ₂

Optimization of the cell operation mode by current strength, feed rate of sodium sulfate solution into the anode chamber and water into the cathode chamber allows to achieve a current efficiency of 95-97% for sulfuric acid, which demonstrates the high efficiency of the technical electrochemical system, i.e. used in the modular cell process.

Example 10. Obtaining chlorine, hydrogen and sodium hydroxide from a solution of alkali metal chloride. In the example, cell No. 1 was used (see Table 2 and FIG. 8c), the anode and cathode of which were installed with an interelectrode distance of IED = 10 mm. The diaphragm was made of ceramic composition: zirconium oxide - 70%, alumina - 27% and yttrium oxide - 3%. The surface of the titanium anode was coated with ORTA, the inlet and outlet nozzles of the anode chamber were made of VT1-00 grade titanium, the diaphragm seals were made of F4 grade fluoroplastic.

The scheme of operation of the electrochemical modular cell in this technology is shown in Fig. 6 and characterizes a fundamentally new technological process - ion selective electrolysis with a diaphragm, which ensures complete separation of the initial saline solution with a concentration of 180 to 250 g / l in modular electrochemical cells in one processing cycle (without return to regeneration of anolyte, without freezing out salt from catholyte and without returning salt to the process, without adding acid to the anode circuit, without high-quality cleaning of saline solution) a mixture of gaseous oxidants (chlorine, chlorine dioxide, ozone) and a solution of sodium hydroxide concentration of 150-170 g / l with a degree of salt conversion from 98 to 99.5% and energy consumption within 2-3 kW × h per kilogram of a gaseous mixture of oxidants . These indicators are very close to theoretically possible, therefore, the process of ion-selective electrolysis with the diaphragm of a solution of sodium chloride have no competitors among known electrochemical systems and technologies.

In the electrochemical cell, the main reaction is the evolution of molecular chlorine in the anode chamber and the formation of sodium hydroxide in the cathode chamber:

NaCl + H ₂ O-e → NaOH + 0.5H ₂ + 0.5Cl ₂

At the same time, with a lower current efficiency, chlorine dioxide synthesis reactions take place directly from saline solution, as well as from hydrochloric acid, which is formed by dissolving molecular chlorine in an anode medium (Cl ₂ + Н ₂ O↔HClO + HCl):

2NaCl + 6H ₂ O-10e → 2ClO ₂ + 2NaOH + 5H ₂ ; HCl + 2H ₂ O-5е → ClO ₂ + 5Н ⁺ .

In addition, in the anode chamber, ozone is formed due to direct decomposition of water and due to the oxidation of the released oxygen:

3H ₂ O-6e → O ₃ + 6H ⁺ ; 2H ₂ O-4e → 4H ⁺ + O ₂ ; ⇒ O ₂ + H ₂₀ -2e → O ₃ + 2H ⁺ .

With a small current efficiency, reactions of formation of active oxygen compounds occur:

H ₂ O-2e → 2H ⁺ + O ^• ; H ₂ Oe → HO ^• + H ⁺ ; 2H ₂ O-3e → HO ₂ + 3H ⁺ .

The process of ion selective electrolysis was carried out as follows. A solution of sodium chloride with a concentration of 200 g / l at a rate of 0.3 l / h was dosed into the anode chamber. The pressure in the anode chamber was maintained equal to 1.1 kgf / cm ² due to the pressure stabilizer at the outlet of the anode chamber (not shown in Fig. 6). After filling the cathode chamber with an atmospheric pressure from the anode chamber, the voltage from the DC source equal to 3.2 V was applied to the cell electrodes. At the same time, a current of 30 A flowed through the cell. The performance of the studied electrochemical system was approximately 40 g of oxidants per hour in chlorine equivalent, which in terms of specific indicators exceeds industrial chlorine electrolyzers.

Example 11. Obtaining electrochemically activated catholyte of fresh water in the technology of preparation of irrigation water enriched with nitrogen fertilizers for plants. To obtain the electrochemically activated fresh water catholyte, cell No. 5 was used (see Table 2 and Fig. 8b). The ideological basis of the technological process under consideration was laid by the work of Justus Liebig, the creator of the theory of mineral nutrition of plants, who almost two centuries ago showed that rainwater contains nitrogen fertilizers of natural origin, absorbed by water from the atmosphere. In atmospheric water, the concentration of these fertilizers is only a fraction of a milligram per liter. But with such a low content, their rainwater has an effect on plant growth that cannot be obtained when watering from earth sources, even when it is more than enough.

It is advisable to impart rainwater properties to ordinary irrigation water from earth sources. “Artificial rainwater” can be prepared by returning to the irrigation water those fertilizers in the same quantities that were taken away from the soil by atmospheric water when it seeps through the ground.

From this follows a particular conclusion: to apply concentrated liquid fertilizers as is done now, is not only irrational, but in some cases also harmful. In particular, ammonia water enters the soil, having a concentration of 25,000-50000 times higher than in rainwater, and, of course, kills all living things.

Nitrogen fertilizers are vital for the normal growth and development of plants.

However, existing technologies for the production and use of nitrogen fertilizers are environmentally hazardous. It is fundamentally impossible to create an environmentally friendly production of nitrogen fertilizers on the basis of existing technologies, since they are based on traditional approaches: synthesis of fertilizers with mandatory generation of production waste; neutralization of production wastes (nitrogen oxides, acid wastewater); fertilizer application in the soil (at the same time, its mineralization inevitably increases); removal of excess salts from the soil by washing it with drainage water. These approaches are embedded in the well-known production processes for the production of nitrogen fertilizers, in particular, sodium and calcium nitrate.

For their implementation, devices of a specific purpose are used: inverters, absorbers, strippers, heat exchangers, refrigerators, filters, sumps, superheaters, condensers, evaporators, crystallizers, drying drums and other equipment. Chemical reagents are used: caustic soda, soda ash, sodium chloride, calcium, magnesium hydroxide, sulfuric and nitric acids, etc. Electricity, steam, hot water are used.

As a result, the production process of nitrate fertilizers is accompanied by the release of pollutants into the environment.

Regardless of the technical level of such production, it inevitably pollutes the environment and worsens the environmental situation. To obtain 1 ton of sodium nitrate, 0.455 tons of nitric acid, 0.03 tons of soda, 2.5 tons of steam (8 atm), 65 m ^{3 of} pure water, 120 kWh of electricity are currently consumed. 0.38 tons of nitrogen oxides are obtained as waste (per 1 ton of sodium nitrate).

Electrochemical technologies implemented in modular electrochemical cells allow you to create an environmentally friendly process for the production of nitrogen fertilizers. Sodium, calcium, magnesium and potassium nitrate are synthesized directly from salts (chlorides, sulfates, carbonates) naturally dissolved in irrigation water.

Water is preliminarily subjected to an electrochemical cathodic treatment in an electrochemical reactor, and then nitric acid is introduced into it in a concentration providing an alkalinity index of water in the range of 6.5-7.5 (depending on soil composition).

The implementation of this process was carried out in laboratory conditions. The main objective of the process was to obtain electrochemically activated fresh water catholyte with an extremely low production of anolyte volume. The operation diagram of the electrochemical cell is shown in Fig. 14. Fresh irrigation water was pumped through the cathode chamber of the cell, the pressure in which was higher than the pressure in the anode chamber by 0.8 kgf / cm ² with a total salinity of 0.24 g / L. The water flow before passing into the cathode chamber of the cell passed through the internal cavity of the anode, cooling it. The flow rate of water ranged from 10 to 20 l / h. After the anode chamber was filled with the filtrate from the cathode chamber, the current source was turned on and a current of 2 A was passed through the cell electrodes. At the beginning of the process, the voltage at the cell electrodes was 25 V, but within a minute it decreased to a constant value of 15 V, which It was explained by an increase in the electrical conductivity of the medium in the anode chamber and stabilization of the concentration of electrolytes in the anode chamber, which provides a constant voltage value at the electrodes of the cell. Measurement of the catholyte pH showed that at a flow rate of 20 liters per hour, the catholyte had a pH of 10.6, and at a flow rate of 10 l / h, the pH was 11.1. When neutralizing catholyte with a weak solution of nitric acid to pH7, 5.2 mg / l of nitrogen fertilizers were detected in cathodically treated water flowing at a speed of 20 l / h, and 9.7 mg / in water flowing at a rate of 10 liters per hour l

When electrochemically treated cathodically treated water (catholyte) is mixed with a very small amount of nitric acid, the reaction of neutralization of nitric acid with hydroxides of alkali and alkaline earth metals occurs, resulting in the formation of calcium, sodium and other metal nitrates, which are effective nitrogen fertilizers:

HNO ₃ + NaOH → NaNO ₃ + H ₂ O

HNO ₃ + Ca (OH) ₂ → Ca (NO ₃ ) ₂ + H ₂ O

Water enriched with nitrogen compounds can be used to irrigate crops of agricultural plants. Water subjected to an electrochemical cathodic treatment in an electrochemical modular cell for some time after the end of the electrochemical exposure is in a metastable state characterized by an abnormal reactivity.

The increased biological activity of fertilizers obtained by the described technology is explained by the fact that the interaction of water with a high degree of metastability is accompanied by the formation of ion-hydrated shells around nitrate ions in solution, which have a special, very long-lived structure. The structural features of the hydration shell have a significant effect on the absorption of fertilizers, which leads to an increase in the efficiency of fertilizers. The solution of nitrogen fertilizers in water obtained in this way retains its high biological activity for up to 3 months.

The environmental cleanliness of the technology is due to the fact that the process of producing nitrate fertilizers is not accompanied by emissions of polluting substances, and the use of fertilizers obtained by the proposed method does not increase the mineral pollution of the soil, since nitrates of alkali and alkaline earth metals are synthesized from salts naturally dissolved in water irrigation. Studies have established that the optimal concentration that ensures the biological need of plants is a nitrate content of 5 to 15 milligrams in 1 liter of irrigation water. It was also found that watering plants during the entire period of cultivation with water with a low nitrate content allows you to get the maximum possible crop yields with high biological value of the product.

Periodic introduction of fertilizers into the soil by known methods is associated with environmental pollution and crop production, because commonly used liquid nitrate fertilizers have a concentration of approximately 25,000 to 5,000 times greater than the biologically optimal one.

Lack of uniformity in the distribution of fertilizer introduced by traditional methods, i.e. periodically, negatively affects crop yields.

Experimental studies have shown the possibility of effective electrochemical conversion of water in a modular cell and made it possible to establish that the total cost of the electrochemical production of nitrogen fertilizers in irrigation water can be 9-11 times less than with known technologies.

Industrial applicability

The invention makes it possible to intensify the processes of electrolysis in a diaphragm type cell and, by improving the design of the cell and the installation procedure for the main elements - electrodes and diaphragm, bring the characteristics of the diaphragm cell closer to the characteristics of electrolyzers with bulk and fluidized electrodes. The use of a diaphragm made of special materials in the cell, as well as the use of a diaphragm and electrodes with different ratios of apparent and true physical surface areas of the electrodes and the diaphragm, allows, in addition, to expand the functionality of the cell when processing various types of electrolytes.

Claims (9)

1. A cylindrical electrochemical cell for processing solutions, containing an internal hollow tubular anode, an external cylindrical cathode, a permeable tubular ceramic diaphragm located between them, dividing the interelectrode space into the anode and cathode chambers, assemblies for mounting, fixing and sealing electrodes and diaphragms placed on the end parts of the cell, and devices for supplying and discharging the treated solutions to the electrode chambers, characterized in that the cathode, anode and diaphragm are installed in the node x and are connected with devices for supplying and discharging the treated solution with the formation of the working part of the cell, along the entire length of which the hydrodynamic characteristics of the electrode chambers and characteristics of the electric field are constant due to the fact that the cathode and anode are made of titanium tubes, while the ratio of the cross-sectional area cathode chamber to the sum of the cross-sectional areas of the anode chamber and the diaphragm is 0.9-1.0, and the length of the working part of the cell is 15-25 of the outer diameters of the anode. 2. A cylindrical electrochemical cell for processing solutions according to claim 1, characterized in that the anode is made of a titanium tube with a developed outer surface on which an electrocatalytic coating is applied, and the ratio of the true (physical) surface area of the anode to the true surface area of the cathode is equal to or greater units, and the outer true surface of the tubular diaphragm is equal to or less than the true surface of the cathode, and the inner true surface of the diaphragm is equal to or less than the true surface of the anode, but less than external outer surface of the diaphragm, and the product of the interelectrode distance by the quotient of dividing the sum of the true surfaces of the anode and cathode by the total volume of the electrode chambers is 3.9-4.1. 3. The cylindrical electrochemical cell for processing solutions according to claim 1, characterized in that the ceramic diaphragm of the cell is made capillary-porous, electroosmotically active from alumina grains surrounded by zirconia particles partially stabilized by rare or rare-earth oxides and has the following composition: oxide aluminum - 60-90 wt.%, while at least 98% of the phase composition of alumina are in alpha form, zirconium dioxide is 10-40 wt.%, while at least 98% of the phase composition of zirconia is in t tragonalnoy modification. 4. A cylindrical electrochemical cell for processing solutions according to claim 3, characterized in that the stabilized zirconia in the tetragonal phase contains one or more oxides selected from the group comprising oxides of yttrium, scandium, ytterbium, cerium, gadolinium, in total 1, 0-10.0 wt.%. 5. The cylindrical electrochemical cell for processing solutions according to claim 1, characterized in that the attachment points of the electrodes and the diaphragm are made in the form of one or more parts of dielectric material each, and devices for supplying and / or withdrawing the processed solution to and from the electrode chambers are made in the form of channels and pipes, combined with the details of the nodes. 6. A cylindrical electrochemical cell for processing solutions according to claim 5, characterized in that the anode cavity is equipped with devices for supplying and discharging the coolant. 7. The cylindrical electrochemical cell for processing solutions according to claim 1, characterized in that the attachment points of the electrodes and the diaphragm are made in the form of one or more parts of dielectric material each, devices for supplying and / or withdrawing the processed solution to and from the cathode chamber are made in channels and nozzles combined with parts of the nodes, and devices for supplying and discharging the treated solution to and from the anode chamber are made in the form of nozzles connected to the internal cavity of the anode and installed and its ends, the end portions of the anode in the openings. 8. The cylindrical electrochemical cell for processing solutions according to claim 1, characterized in that the attachment points of the electrodes and the diaphragm are made in the form of one or more parts of dielectric material each, devices for supplying and discharging the processed solution to and from the cathode chamber are made in the form of holes and nozzles located at the end sections of the cathode, and devices for supplying and outputting the treated solution to and from the anode chamber are made in the form of nozzles connected to the inner cavity of the anode, in that the end portions of the anode openings. 9. A cylindrical electrochemical cell for processing solutions according to claim 8, characterized in that additional holes are made in the anode body, uniformly spaced along its length along the entire length of the working part of the cell.

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