RU2631428C1 - Method for electrochemical synthesis of alkali metal ferrates - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: in the method, a device is used for the electrochemical synthesis of alkali metal ferrates with, at least, two electrochemical reactors, each consisting of a vertically disposed inner anode - a cylindrical rod based on iron, an outer cylindrical titanium cathode, and a cylindrical ceramic ion transport diaphragm placed between them, which form closed volumes of the anodic and cathodic chambers of the electrochemical reactor due to the presence of upper and lower bushings having inputs and outputs in the lower and upper parts. At the same time, the lower inputs of the anode chambers of all electrochemical reactors are connected to the lower anode collector, into which a solution of alkali metal hydroxide is supplied by a dosing pump. The upper outputs of the anode chambers of all electrochemical reactors are connected to the upper anode collector, from which the electrochemical decomposition products of the aqueous solution of alkali metal hydroxide pass through a separator separating the gaseous and liquid phases of the electrochemical decomposition products. Herewith the gaseous phase in the form of oxygen is withdrawn to the atmosphere, and the liquid phase containing the alkali metal ferrate is withdrawn for further use.

EFFECT: reduction of energy consumption per unit of production and ensuring the production of alkali metal ferrate in one stage by decomposition of alkali metal hydroxides in the electrochemical reactor.

2 dwg

Description

The invention relates to the field of chemical technology, in particular to methods of electrochemical oxidation of iron to obtain an oxidizing reagent of a ferrate (VI) FeO ₄ ^2- .

From the "prior art" there is known a method for the integrated production of chlorine-containing reagents and sodium ferrate using a device that includes chlorine and ferrate electrolysis units connected to a current source. Elements of the device are connected to a direct current source. A salt solution having a limiting salt concentration is fed into the anode chamber from the tank. The released chlorine enters the separator, where anolyte is formed and where the upper part of this analyte is absorbed, which contains the highest concentration of chlorine for further practical consumption for its intended purpose, i.e. for the process of disinfecting liquid media, in particular drinking or industrial water. The main chemical reaction occurring at the anode: 2Cl ^- -2 ^e- → Cl2

In the cathode chamber, into which tap water is supplied from the tank, an alkali solution is generated, and from the separator, hydrogen generated during electrolysis separated from the alkali solution is removed from the device. From the separator, the alkali solution is fed into the anode chamber. The main chemical reaction taking place in the chamber:

2H ₂ O + 2 ^е- → Н ₂ + 2ОН ^-

The anode chamber is designed to produce sodium ferrate, for which alkali is fed into it from the separator. In the separator, oxygen formed during electrolysis is released and removed outside the device. A solution of sodium ferrate from the separator is fed for further use as intended as an oxidizing agent and a coagulant (see RF patent No. 162651, class IPC С25В 9/08, publ. 06/20/2016).

There is the following technical problem:

- the electrodes of both electrolytic cells have flat shapes, and the casing is a box-shaped design, which leads to the formation of stagnant zones in the corners of the casing and does not provide a uniform electrolysis flow in the volume of the structure, which leads to an increase in power consumption per unit of the resulting product;

- obtaining alkali metal ferrate is carried out in two stages using two electrolysis cells.

The objective of the present invention is to remedy the above disadvantages.

The technical result consists in reducing energy consumption per unit of production and ensuring the production of alkali metal ferrate in one stage by decomposition of alkali metal hydroxides in an electrochemical reactor.

The technical result is ensured by the fact that the method for the electrochemical synthesis of alkali metal ferrates includes the use of a device for the electrochemical synthesis of alkali metal ferrates, containing electrochemical reactors, each of which has an anode, a cathode and an ion-permeable diaphragm, connecting it to an electric current source. The method uses a device for the electrochemical synthesis of alkali metal ferrates with at least two electrochemical reactors, each of which consists of a vertically located internal anode - a cylindrical rod based on iron, an external cylindrical titanium cathode and a cylindrical ceramic ion-permeable diaphragm located between them, which form closed volumes of the anode and cathode chambers of the electrochemical reactor due to the presence of its upper and lower bushings having lower her and the upper parts of the entrances and exits. In this case, the lower inputs of the anode chambers of all electrochemical reactors are connected to the lower anode collector, into which an alkali metal hydroxide solution is supplied by a metering pump. The upper outputs of the anode chambers of all electrochemical reactors are connected to the upper anode collector, from which the products of electrochemical decomposition of an aqueous solution of alkali metal hydroxide pass through a separator that separates the gaseous and liquid phases of the products of electrochemical decomposition. In this case, the gaseous phase in the form of oxygen is discharged into the atmosphere, and the liquid phase containing alkali metal ferrate is diverted for further use. In addition, at the same time, another alkaline metal hydroxide solution is supplied by another metering pump through the lower cathode collector and the lower inputs of the cathode chambers. The upper inlets of the cathode chambers of all electrochemical reactors are connected to the upper cathode collector, from which the products of electrochemical decomposition are fed to a catholyte collection tank, where they are separated into a gaseous and liquid phase, while the gaseous phase in the form of hydrogen is discharged into the atmosphere, and the liquid phase in the form of alkaline hydroxide metal sent for recycling and poured into the capacity of the working solution of alkali metal hydroxide. In addition, the device for the electrochemical synthesis of alkali metal ferrates has two metering pumps that provide a separate supply of a working solution of alkali metal hydroxide in the anode and cathode chambers of electrochemical reactors.

The essence of the present invention is illustrated by the following illustrations:

In FIG. 1 shows an electrochemical reactor.

In FIG. 2 is a hydraulic diagram of an apparatus for electrochemical treatment of an alkali metal hydroxide solution (in particular potassium or sodium).

The following structural elements are displayed in the illustration:

1 - anode,

2 - cathode,

3 - aperture

4 - cathode chamber,

5 - anode chamber,

6 - anode sleeve,

7 - cathode sleeve,

8, 9 - terminals

10 - anode fittings,

11 - cathode fittings.

The method uses a device for the electrochemical synthesis of alkali metal ferrates, which includes at least two (from two to twelve) electrochemical reactors. Moreover, each electrochemical reactor consists of an inner cylindrical rod based on iron anode 1, an external tubular titanium cathode 2 and a tubular ceramic ion-permeable diaphragm 3 placed between them. The lower and upper ends of the electrodes 1, 2 and ion-permeable diaphragms 3 are closed by cathode and anode bushings 6, 7, due to which the closed anode and cathode chambers 4, 5 are formed. Chambers 4, 5 have separate anode input and output fittings 10 and cathode input and output fittings 11 above and below. Lemma 8, 9 is switched on.

The lower inputs of the anode chambers 4 of all electrochemical reactors are connected by nipples 10 to the lower anode collector, and the upper outputs of the anode chambers 4 of all electrochemical reactors are connected by nipples 10 to the upper anode collector, and the upper entrances of the cathode chambers 5 of all electrochemical reactors are connected by cathode nozzles 11 and the upper cathode collector and the lower inputs of the cathode chambers 5 of all electrochemical reactors are connected by cathode fittings 11 to the lower cathode collector. In addition, the anode and cathode chambers 4, 5 are configured to separately feed into them a working solution of alkali metal hydroxide using two metering pumps.

The implementation of the device with electrodes and a cylindrical membrane shape with the possibility of separate feeding into the anode and cathode chambers 4, 5 of the working solution of alkali metal hydroxide using two metering pumps eliminates the formation of stagnant zones in the reactor, which ensures uniform electrolysis flow in the design volume of the entire device.

The installation preferably contains two electrochemical reactors P ₁ -P _i . The anode chambers of the electrochemical reactors P ₁ -P _{i are} connected with the upper fittings to the collector by the anode upper CAB, and the lower fittings are connected to the collector by the anode lower CAS.

The cathode chambers of electrochemical reactors P ₁ -P _{i are} connected by upper fittings to the upper cathode cathode collector and lower fittings to the lower cathode cathode collector.

Before applying power to the electrochemical treatment of the alkali metal hydroxide solution, the anode and cathode chambers of the P ₁ -P _i electrochemical reactors are filled with this solution through the lower collectors KAN and KKN using metering pumps ND1, ND2.

The products of electrochemical decomposition from the anode chambers of the reactors through the upper anode collector enter the SGH gas-liquid separator and are separated there into a gaseous phase (oxygen that enters the atmosphere) and a liquid phase containing alkali metal ferrate and FeO ₄ ^2- , sent for further use as a coagulate.

The products of the cathodic decomposition of an electrolyte solution from the cathodic chambers of P ₁ -P _i electrochemical reactors through the collector the upper cathode cathode discharge pump enters the separator EC, where they are separated into a gaseous phase (hydrogen that is released into the atmosphere) and a liquid phase containing an aqueous solution of alkali metal hydroxide, which fed to recycling and discharged into a container with a working solution of hydroxide.

Claims (1)

The method of electrochemical synthesis of alkali metal ferrates, including the use of a device for the electrochemical synthesis of alkali metal ferrates, containing electrochemical reactors, each of which has an anode, a cathode and an ion-permeable diaphragm, connecting it to an electric current source, characterized in that the method uses an electrochemical synthesis device alkali metal ferrates with at least two electrochemical reactors, each of which consists of a vertically arranged the internal anode - a cylindrical rod based on iron, an external cylindrical titanium cathode and a cylindrical ceramic ion-permeable diaphragm placed between them, which form closed volumes of the anode and cathode chambers of the electrochemical reactor due to the presence of upper and lower bushings having inputs and outputs, while the lower inputs of the anode chambers of all electrochemical reactors are connected to the lower anode collector, into which the alkali hydroxide solution is fed by a metering pump metal, and the upper outputs of the anode chambers of all electrochemical reactors are connected to the upper anode collector, from which the products of the electrochemical decomposition of an aqueous solution of alkali metal hydroxide pass through a separator that separates the gaseous and liquid phases of the products of electrochemical decomposition, while the gaseous phase in the form of oxygen is discharged into the atmosphere and the liquid phase containing alkali metal ferrate is diverted for further use, in addition, simultaneously with another metering pump through the lower cathode collector and the lower inputs of the cathode chambers supply an alkali metal hydroxide solution, the upper inputs of the cathode chambers of all electrochemical reactors are connected to the upper cathode collector, from which the products of electrochemical decomposition are fed to the catholyte collection tank, where they are separated into a gaseous and liquid phase, while the gaseous phase in the form of hydrogen is discharged into the atmosphere, and the liquid phase in the form of an alkali metal hydroxide is sent for recycling and poured into the tank of the alkali hydroxide working solution In addition, the device for the electrochemical synthesis of alkali metal ferrates has two metering pumps that provide a separate supply of a working solution of alkali metal hydroxide to the anode and cathode chambers of electrochemical reactors.

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