CN104524942A - Method and device for liquid-phase purification of industrial sulphur dioxide waste gas in synergetic effect of electrodialysis - Google Patents

Abstract

The invention discloses a method for electrodialysis and liquid phase purification of sulfur dioxide industrial waste gas. The method combines electrodialysis technology and liquid phase catalytic oxidation technology and is applied to the absorption and purification of sulfur dioxide waste gas. The sulfur dioxide waste gas is fed into water as the absorption The cathode chamber of the liquid, under the synergistic oxidation of catalyst and electrochemistry, sulfuric acid with a low concentration is generated in water, and the dilute sulfuric acid generated by catalytic oxidation in the cathode chamber is enriched into the anode chamber by electrodialysis, so as to realize catalytic oxidation and product separation. Effective separation and enrichment and concentration of products, so as to obtain concentrated sulfuric acid with a concentration that meets the requirements of the product grade; this method integrates multiple reactions in one reactor, increases the capacity and efficiency of liquid phase absorption and purification of sulfur dioxide, and shortens the production of sulfuric acid. The technological process reduces the cost of purification. This technology is conducive to the resource utilization of industrial waste gas and can produce huge economic and social benefits.

Description

Method and device for electrodialysis combined with liquid phase purification of sulfur dioxide industrial waste gas

technical field

The invention relates to a method and a device for purifying and treating low-concentration sulfur dioxide industrial waste gas by using electrodialysis technology, belonging to the field of environmental engineering.

Background technique

SO ₂ is one of the common major air pollutants. SO ₂ pollution is mainly caused by energy consumption, and economic development is inseparable from the support of energy. China's energy composition is dominated by coal, and a large amount of fuel with high sulfur content is burned Coal is an important factor leading to massive _SO emissions and severe pollution. The Bulletin on the State of the Environment in China shows that since 1990, the air pollution in large and medium-sized cities in my country has been serious, and the air pollution in small towns has also tended to increase. In recent years, the scope and degree of smog weather have increased. In the purification treatment of SO ₂ gas, a lot of researches have been carried out at home and abroad. There are three types of sulfur purification: before, during, and after combustion. There are solid-phase absorption, liquid-phase absorption, solid-phase catalytic oxidation, and liquid-phase catalytic oxidation methods for the purification of SO ₂ tail gas. The research on the purification of SO ₂ by electrochemical methods has been There are electron beam desulfurization method and plasma method. In the traditional sulfuric acid production process by contact oxidation, the process of converting SO ₂ to SO ₃ is required to be completed at high temperature and in the presence of a catalyst. The gas-phase oxidation of SO ₂ requires high energy and high cost. Oxidation of SO ₂ in the liquid phase can make the conversion Energy loss is greatly reduced.

Electrodialysis technology is to separate the electrolyte from the solution by using the selective permeability of the ion exchange membrane under the action of a direct current electric field, with the potential difference as the driving force, so as to achieve the purpose of desalination, concentration, refinement or purification of the solution. Electrodialysis technology has many advantages, such as: small footprint, less infrastructure investment, labor saving, convenient maintenance, easy automation, etc.; it does not consume a lot of fuel like distillation that turns more than 90% of water into steam. It is also different from reverse osmosis, which needs to use a high-pressure pump to squeeze a large amount of water molecules out of the semi-permeable membrane, or the frequent regeneration of ion exchange, which discharges acid-base waste liquid and pollutes the environment again. In these respects, electrodialysis has unique advantages.

The patent with the publication number CN 1572359 A discloses a method and device for desulfurizing waste gas containing sulfur oxides. The method is to pass _SO2 into a soluble alkaline solution for absorption, and electrodialysis technology is used to regenerate the absorption solution. In the process, the process uses multiple sets of devices such as absorption device, regeneration device, and circulation device. The core is the conversion between bisulfite and sulfite, which constitutes the absorption and regeneration cycle of desulfurization. The by-products containing sulfuric acid need to be Additional harmless treatment.

The patent with the publication number CN 102008875A discloses a method for smelting flue gas by using low-concentration SO ₂ , which includes four processes of low-concentration sulfur dioxide absorption, absorption-rich desorption, desorption of poor liquid sonoelectrochemical dialysis, and desorption of gas to produce acid , using citrate to absorb the rich solution for desorption, the obtained Gaochun SO ₂ is used for acid production, and the method of sonoelectrochemical membrane dialysis is used to purify and regenerate the desorbed poor solution. The reaction process is the old process of SO ₂ acid production with two conversions and two absorptions improvement of.

Contents of the invention

The purpose of the present invention is to provide a method for electrodialysis and liquid phase purification of sulfur dioxide industrial waste gas. This method is a process for purifying low-concentration sulfur dioxide waste gas and producing sulfuric acid completely different from the existing sulfur dioxide two-transformation and two-absorption purification process. The process will catalyze Oxidation, enrichment and concentration are integrated in one reactor, and the process conditions are mild and the process flow is simple, which is convenient for extensive industrial production, reduces purification costs, and reduces secondary pollution.

In this method, water is used as the absorbing liquid, transition metal salts are added as active catalysts, and the waste gas with a flow rate of 20-5000ml/min and a sulfur dioxide concentration of 50-5000ppm is passed into the electrodialysis reactor under the condition of a voltage of 0.5-6V. During the mixed flow process of the aeration chamber and the cathode chamber, _SO2 is absorbed and oxidized, and the sulfuric acid with a lower concentration generated in the cathode chamber enters the anode chamber through the ion exchange membrane under the action of an electric field to be concentrated, and part of the sulfurous acid that has not been completely oxidized is also In the anode chamber, it is electrochemically oxidized to sulfuric acid, and the treated gas is purified gas.

The transition metal salt is one of Fe ³⁺ , Mn ³⁺ , Fe ²⁺ , Mn ²⁺ , Co ²⁺ , Ni ²⁺ , Zn ²⁺ salt, and the concentration is 0.001-1 mol/L.

The ion-exchange membrane is a perfluorosulfonic acid/manganese oxide/polytetrafluoroethylene composite ion-exchange membrane, which is prepared as follows:

(1) Add an equal amount of surfactant solution with an equal volume of 0.1-1% mass percentage concentration to the perfluorosulfonic acid solution with a mass percentage concentration of 5%, mix, stir, and sonicate to make it evenly distributed;

(2) Mix manganese oxide powder, tetraethyl orthosilicate, absolute ethanol and sulfuric acid in a mass ratio of 0.1:1:5:0.1～0.3:2:5:0.1, stir at high speed for 10～24 hours, and form Manganese oxide sol, adding the sol to a prepared equal-quality perfluorosulfonic acid solution to obtain a perfluorosulfonic acid/manganese oxide solution;

(3) Clean the polytetrafluoroethylene porous membrane with ethanol and deionized water, dry it, soak it in isopropanol for 12-24 hours and dry it;

(4) Soak the treated polytetrafluoroethylene porous membrane in perfluorosulfonic acid/manganese oxide solution for 24-48 hours, take it out, roll it, dry it at 120°C, then soak it and roll it again for 4-5 times , to obtain perfluorosulfonic acid/manganese oxide/polytetrafluoroethylene composite ion exchange membrane.

Described tensio-active agent is Triton X-100.

Another object of the present invention is to provide a device for realizing electrodialysis and liquid phase purification of industrial waste gas of sulfur dioxide, in which catalytic oxidation and enrichment and concentration are completed in one reactor. The device has a simple structure, is easy to operate and control, and can improve absorption efficiency , catalyst activity, sulfuric acid yield and reduce production costs.

The device includes an electrodialysis chamber 2 and a power supply, wherein the electrodialysis chamber is a cylindrical closed chamber, and the electrodialysis chamber is divided into a lower aeration chamber 9, a middle reaction chamber 14, and an upper separation chamber by a lower partition 13 and an upper partition 17. 20. The aeration sieve plate 12 is installed under the lower partition plate 13, the upper part of the lower aeration chamber 9 is provided with a cathode liquid inlet 8 and is located above the aeration sieve plate 12, and the lower part of the lower aeration chamber is provided with a mixed gas inlet 11 and is located at the aeration Below the sieve plate 12; one side of the upper separation chamber 20 is provided with a cathode liquid outlet 3, and the upper part of the upper separation chamber is provided with a purified gas outlet 19; the anode plate, ion exchange membrane and cathode plate are spirally wound in the middle reaction chamber 14, and the ions The exchange membrane 5 is arranged between the cathode plate 4 and the anode plate 6, the gap between the ion exchange membrane and the cathode plate forms the cathode chamber, the gap between the anode plate and the ion exchange membrane forms the anode chamber, and the reaction chamber cathode is opened on the lower partition 13 The liquid inlet 7 is also communicated with the cathode chamber, and the catholyte outlet 15 of the reaction chamber is provided on the upper partition 17 and is communicated with the cathode chamber. The cathode column 1 is connected to the cathode plate 4, the anode column 16 is connected to the anode plate 6, the cathode column 1 is connected to the negative pole of the power supply, and the anode column 16 is connected to the positive pole of the power supply.

The electrodialysis chamber is made of polytetrafluoroethylene plates, the cathode plate is a stainless steel electrode plate, and the anode plate is a titanium or titanium-plated oxidized metal electrode plate.

When the device is in use, water is used as the absorbing liquid of sulfur dioxide, a transition metal salt catalyst is added to the water, and the prepared absorbing liquid is injected into the lower aeration chamber from the catholyte inlet 8, and the sulfur dioxide gas enters from the mixed gas inlet 11 and passes through the gas The sieve plate 12 is fully mixed with the absorption liquid, and then enters the cathode chamber of the electrodialysis chamber from the catholyte inlet 7 for absorption and catalytic oxidation; sulfur dioxide reacts with water to generate sulfurous acid, and to generate sulfuric acid, a catalyst is needed to catalyze the oxidation of sulfurous acid to sulfuric acid. The catalyst in this process is a transition metal salt, which is easily soluble in water, has high catalytic activity for sulfur dioxide, and can be regenerated and used through the electrochemical process of the device itself; Under the action, through the ion exchange membrane with strong basic active exchange groups, the sulfate ions are enriched in the anode chamber, and the sulfate ions combine with the hydrogen ions generated by anode electrolysis to generate high-concentration sulfuric acid, and the sulfuric acid passes through the anolyte outlet 18 Collecting, the cathodic chamber absorbing liquid enters the upper separation chamber through the catholyte outlet 15 of the reaction chamber, the purified gas is discharged through the purified gas outlet 19, and the absorbing liquid is discharged through the catholyte outlet 3.

The voltage value between the two electrodes used in the enrichment and concentration process of the present invention is adjusted according to the size of the membrane area and the electrode spacing, so that the working current density of the electrodialysis device is kept at 1-5A/m ² .

The present invention utilizes electrodialysis technology to process sulfur dioxide waste gas, takes water as the main absorbing liquid of sulfur dioxide, and when sulfur dioxide dissolves in water, the following balance exists in the absorbing liquid:

;

;

;

After sulfur dioxide dissolves in water, it mainly exists in the form of sulfite and bisulfite depending on the pH. Under high pH conditions (6-14), it mainly exists in the form of sulfite. At low pH (1-4 ) conditions, mainly in the form of bisulfite. This process is mainly reflected in low pH conditions, so the main target of liquid-phase catalytic oxidation is bisulfite.

In the selection of the catalyst, it must be considered that the catalyst must be able to reach a sufficiently high valence state to capture electrons from S(IV), and then generate an active intermediate, which in turn promotes the reaction. Since high-valence ions are weakened after capturing electrons, there must be an energy-enhancing method to make the weakened ions return to a high-valence state.

Experiments found that Mn and Fe are better catalysts at low pH, Ni and Zn have low catalytic activity due to the lack of variable valence states in weak media, and Cu is not oxidative at low pH, so it cannot be converted from S(Ⅳ) Species produce pass chains, thus exhibiting very weak catalytic activity.

Under the action of the catalyst, a catalytic oxidation reaction occurs, and bisulfite is catalytically oxidized to sulfate. The liquid-phase catalytic oxidation process of sulfur dioxide includes two sub-processes, chemical absorption and catalytic oxidation. Chemical absorption is a sulfur fixation process, and catalytic oxidation is the desulfurization process. The overall reaction of these two parts is:

;

The two reaction processes of liquid-phase absorption and catalytic oxidation are completed in the left half of the "Schematic Diagram of the Working Principle of the Invention", that is, in the cathode chamber. The reaction and description are shown in Figure 1.

In the whole electrodialysis device, the sulfate ions generated by catalytic oxidation in the cathode chamber migrate to the anode chamber through the ion exchange membrane under the action of the electric field, thereby enriching and concentrating in the anode chamber. In the anode chamber, sulfate ions combine with hydrogen ions generated by anode electrolysis to generate high-concentration sulfuric acid, which is reflected as follows:

;

In addition, some sulfite and bisulfite will also migrate to the anode chamber through the ion exchange membrane. Due to the oxidation of the anode, the dialyzed sulfite and bisulfite will be converted into sulfate, and then combined with hydrogen The ions combine to form sulfuric acid.

The advantages of the present invention are:

(1) The present invention can be applied to the treatment of sulfur-containing tail gas from smelters, sulfur-containing tail gas from power plants, and oil cracking and desulfurization waste gas from oil refineries. Recycling;

(2) The present invention changes the traditional two-transformation and two-absorption process in sulfur dioxide tail gas acid production, and uses electrodialysis technology to assist liquid phase absorption and oxidation to realize directional control of purified products and enrichment and concentration of target products, which can not only shorten the process flow, And reduce the cost of purification;

(3) The present invention also changes the traditional application method of electrodialysis only for water treatment or regeneration treatment, and applies electrodialysis technology to the absorption and purification of waste gas, opening up a new way to absorb, purify and utilize toxic and harmful waste gas;

(4) In the electrodialyzer, the oxygen generated during the anode electrolysis process can effectively solve the problem of low oxidation conversion efficiency caused by low oxygen content or low oxygen solubility in the tail gas;

(5) The anode electrochemical oxidation of the electrodialyzer can theoretically enhance the catalytic activity and stability, and can also promote the conversion of catalytically active metal ions from a low-valence state to a high-valence state to regenerate the catalyst;

(6) The reaction conditions are mild and can be carried out at room temperature, and the process flow is simple. In addition, multipolar membrane and multipolar chamber process devices can be used to improve efficiency.

(7) This method integrates a variety of reactions in one reactor. While obtaining a high purification rate of low-concentration sulfur dioxide gas, it can simultaneously produce high-concentration sulfur dioxide gas by using liquid phase absorption, catalytic oxidation, electrodialysis and ion exchange. The sulfuric acid product increases the capacity and efficiency of liquid phase absorption and purification of sulfur dioxide, shortens the process flow of sulfuric acid production, and reduces the cost of purification. This technology is conducive to the resource utilization of industrial waste gas and can produce huge economic and social benefits.

Description of drawings

Fig. 1 is a schematic diagram of the working principle of the present invention;

Fig. 2 is the structural representation of electrodialysis device of the present invention;

Fig. 3 is the schematic diagram of cathode plate, ion exchange membrane, anode plate spiral winding of the present invention;

Fig. 4 is a schematic process flow diagram of the present invention;

In the figure: 1- cathode column; 2- electrodialysis chamber; 3- catholyte outlet; 4- cathode plate; 5- ion exchange membrane; 6- anode plate; 7- catholyte inlet in reaction chamber; 8- catholyte inlet; 9-lower aeration chamber; 10-anolyte inlet; 11-mixed gas inlet; 12-storm sieve plate; 13-lower partition; 14-middle layer reaction chamber; 15-reaction chamber catholyte outlet; 16-anode column ; 17-upper partition; 18-anolyte outlet; 19-purified gas outlet; 20-upper separation chamber;

21-Sulfur dioxide tail gas after dust removal and cooling, 22-Air, 23-Air pump, 24-Air filter, 25-Solenoid valve, 26-Mixer, 27-Gas flow controller, 28-Power controller, 29-Electric Dialysis reactor, 30-dehumidifier, 31-catholyte storage tank, 32-anolyte storage tank, 33-concentrated sulfuric acid, 34-sulfur dioxide analyzer, 35-purge gas.

Detailed ways

The present invention will be described in further detail below in conjunction with the accompanying drawings and embodiments. It should be noted that these embodiments are preferred examples for further understanding of the present invention, and are not intended to limit the present invention.

Embodiment 1: The method and device of this electrodialysis cooperative liquid phase purification sulfur dioxide industrial waste gas, specific content is as follows:

1. The preparation steps of perfluorosulfonic acid/manganese oxide/polytetrafluoroethylene composite ion exchange membrane are as follows:

(1) Add an equal volume mass percentage concentration of 0.1% surfactant solution (Triton X-100) to the perfluorosulfonic acid solution with a mass percentage concentration of 5% to mix, stir, and sonicate to make it evenly distributed;

(2) Mix manganese oxide powder, tetraethyl orthosilicate, absolute ethanol and sulfuric acid at a mass ratio of 0.1:1:5:0.1, stir at high speed for 10 hours to form a manganese oxide sol, add the sol to prepare In the perfluorosulfonic acid solution of equal quality, obtain perfluorosulfonic acid/manganese oxide solution;

(3) Wash the polytetrafluoroethylene porous membrane with ethanol and deionized water, dry it, soak it in isopropanol for 24 hours and dry it;

(4) Soak the polytetrafluoroethylene porous membrane in step (3) in the perfluorosulfonic acid/manganese oxide solution for 30 hours, take it out, roll it, dry it at 120°C, then soak it and roll it again and repeat 4 times, that is A perfluorosulfonic acid/manganese oxide/polytetrafluoroethylene composite ion exchange membrane is obtained.

2. A device using perfluorosulfonic acid/manganese oxide/polytetrafluoroethylene composite ion exchange membrane as an ion exchange membrane for electrodialysis and liquid phase purification of sulfur dioxide industrial waste gas, which includes an electrodialysis chamber 2 and a power supply, wherein the electrodialysis chamber 2 It is a cylindrical closed chamber. The electrodialysis chamber is divided into a lower aeration chamber 9, a middle reaction chamber 14, and an upper separation chamber 20 by a lower partition 13 and an upper partition 17. The aeration sieve plate 12 is installed under the lower partition 13. The upper part of the lower aeration chamber 9 is provided with a catholyte inlet 8 and is located above the aeration sieve plate 12, and the lower part of the lower aeration chamber 9 is provided with a mixed gas inlet 11 and is located below the aeration sieve plate 12; one side of the upper separation chamber 20 is provided with Catholyte outlet 3, the top of upper separation chamber 20 is provided with purified gas outlet 19; anode plate 6, ion exchange membrane 5 and cathode plate 4 are spirally wound in middle layer reaction chamber 14, ion exchange membrane 5 is arranged on cathode plate 4 and Between the anode plates 6, the gap between the ion-exchange membrane and the cathode plate forms the cathode chamber, the gap between the anode plate and the ion-exchange membrane forms the anode chamber, and the lower dividing plate 13 has a reaction chamber catholyte inlet 7 and communicates with the cathode chamber. The catholyte outlet 15 of the reaction chamber is opened on the upper partition 17 and communicates with the cathode chamber. The anolyte inlet 10 and the anolyte outlet 18 are respectively arranged in the lower and upper parts of the electrodialysis chamber and communicated with the anode chamber. The cathode column 1 is connected to the cathode plate 4 connection, the anode column 16 is connected to the anode plate 6, and the cathode column 1 and the anode column 16 are respectively connected to the power supply. Stainless steel electrode plate, the anode plate is a titanium electrode plate that is not easily corroded and has catalytic activity for sulfur dioxide. (See Figure 2-3).

3. At room temperature, the device uses pure water with a conductivity (25°C) less than 5mS/m and a pH value of 6.8 as the absorption liquid, adding manganese oxide as the active catalyst, and configuring the water and catalyst at a mass ratio of 20:1 to process The absorption liquid of low-concentration sulfur dioxide flue gas is directly put into the cathode chamber of the electrodialyzer, and under the condition of a voltage of 1V, the waste gas with a flow rate of 500ml/min and a sulfur dioxide concentration of 1000ppm is passed into the electrodialysis reactor. During the mixed flow process with the cathode chamber, _SO2 is absorbed and oxidized, and the sulfuric acid with a lower concentration generated in the cathode chamber enters the anode chamber through the ion exchange membrane to be concentrated under the action of an electric field, and part of the sulfurous acid that is not completely oxidized is also in the anode chamber The electrochemical oxidation is sulfuric acid, and the treated gas is purified gas.

According to the electrodialysis process flow chart of purifying low-concentration sulfur dioxide industrial waste gas shown in Figure 4, using the above-mentioned device, the main components in the flue gas: the sulfur dioxide tail gas 21 generated by combustion and air 22 after dedusting and cooling (air 22 passes through the air filter 24 Pumped out by air pump 23) Use gas flow controller 27 to control each gas component through electromagnetic valve 25, form simulated flue gas in mixer 26, inject the absorption liquid in catholyte storage tank 31 from catholyte inlet 8 into the lower layer Aeration chamber 9, exhaust gas enters the lower aeration chamber 9 from the mixed gas inlet 11 of the electrodialysis reactor 29 and is fully mixed with the absorption liquid through the storm sieve plate 12, and then enters the cathode chamber of the electrodialysis chamber through the catholyte inlet 7 Absorption catalytic oxidation; the absorption liquid is continuously rotated and mixed between the wound cathode plate and the ion exchange membrane to accelerate the reaction, and the generated sulfate and some sulfites, the cathode plate 4 is connected to the cathode column 1 leading to the external power controller 28, The anode plate 6 is connected to the anode column 16 leading to the external power controller 28, and the negative ions generated by the reaction enter the anode chamber through the ion exchange membrane 5 under the action of the electric field between the cathode plate 4 and the anode plate 6, and the anode chamber is filled with anolyte. The water injected into the inlet 10 or the circulating dilute sulfuric acid that does not meet the concentration requirements enrich the sulfate ions in the anode chamber, and the oxygen generated by the electrolysis of the anode plate 6 further oxidizes the incompletely oxidized sulfite that permeates through the ion exchange membrane 5 It is sulfate radical, and sulfate radical ion combines with the hydrogen radical ion produced by anode electrolysis to generate high-concentration sulfuric acid, and sulfuric acid is extracted into the anolyte storage tank 32 through the anolyte outlet 18 to become the final product sulfuric acid 33 after being homogenized and inspected; The other gas components remaining in the chamber after the catalytic oxidation and electrodialysis reaction are carried by the catholyte and enter the upper separation chamber 20 through the catholyte outlet 15 of the reaction chamber, and the purified gas 35 enters the dehumidifier 30 through the purified gas outlet 19 to dehumidify and sulfur dioxide The analyzer 34 is emptied after the analysis and detection reaches the standard, and the degassed absorption liquid flows back to the catholyte storage tank 31 through the catholyte outlet 3 to continue to be recycled.

During the absorption process of low-concentration sulfur dioxide, the current density between the two electrodes is kept at 3A/m ² . Within 10-100 hours of starting treatment, the concentration of sulfur dioxide in the outlet gas remained below 100ppm; after 8 hours of treatment, the concentration of sulfuric acid in the anolyte storage tank rose to 10%, and after 24 hours of treatment, the concentration of sulfuric acid in the anolyte storage tank rose to 30%, meeting the sulfuric acid reuse concentration requirements.

Embodiment 2: The method and device for the electrodialysis and liquid phase purification of sulfur dioxide industrial waste gas, the specific contents are as follows:

1. The preparation steps of perfluorosulfonic acid/manganese oxide/polytetrafluoroethylene composite ion exchange membrane are as follows:

(1) Add an equal volume mass percentage concentration of 0.5% surfactant solution (Triton X-100) to the perfluorosulfonic acid solution with a mass percentage concentration of 5% to mix, stir, and sonicate to make it evenly distributed;

(2) Mix manganese oxide powder, tetraethyl orthosilicate, absolute ethanol and sulfuric acid at a mass ratio of 0.2:2:5:0.1, stir at high speed for 15 hours to form a manganese oxide sol, add the sol to prepare In the perfluorosulfonic acid solution of equal quality, obtain perfluorosulfonic acid/manganese oxide solution;

(3) Wash the polytetrafluoroethylene porous membrane with ethanol and deionized water, dry it, soak it in isopropanol for 15 hours and dry it;

(4) Soak the polytetrafluoroethylene porous membrane in step (3) in the perfluorosulfonic acid/manganese oxide solution for 48 hours, take it out, roll it, dry it at 120°C, then soak it and roll it again and repeat 4 times, that is A perfluorosulfonic acid/manganese oxide/polytetrafluoroethylene composite ion exchange membrane is obtained.

2. Using perfluorosulfonic acid/manganese oxide/polytetrafluoroethylene composite ion exchange membrane as a device for electrodialysis and liquid phase purification of sulfur dioxide industrial waste gas with ion exchange membrane. Metal electrode plates.

3. At room temperature, the device uses water with a conductivity (25°C) less than 1mS/m and a pH value of 7 as the absorption liquid, and manganese sulfate is added as the active catalyst, and the mass ratio of water and catalyst is 10:1. The absorption solution of sulfur dioxide flue gas with a concentration of sulfur dioxide is directly put into the cathode chamber of the electrodialyzer. Under the condition of a voltage of 4V, the waste gas with a flow rate of 1000ml/min and a sulfur dioxide concentration of 5000ppm is passed into the electrodialysis reactor. _SO2 is absorbed and oxidized during the mixed flow process in the cathode chamber, and the sulfuric acid with a lower concentration generated in the cathode chamber enters the anode chamber through the ion exchange membrane to be concentrated under the action of an electric field, and part of the sulfurous acid that has not been completely oxidized is also charged in the anode chamber. Chemically oxidized to sulfuric acid, the treated gas is purified gas, and the concentration of sulfur dioxide in the purified gas is lower than 200ppm.

During the absorption process of low-concentration sulfur dioxide, the current density between the two electrodes is kept at 4A/m ² , after electrochemical ionic membrane dialysis, the sulfate concentration in the absorption liquid is reduced, and the barren liquid after dialysis is reused in the purification and absorption process, making the reactor The continuous purification ability of the absorption liquid for sulfur dioxide. The sulfuric acid concentration in the electrodialyzer anolyte storage tank increases with the dialysis time, and after 24 hours of continuous treatment, the sulfuric acid concentration in the anolyte storage tank can reach 40%.

Embodiment 3: The method and device for the electrodialysis and liquid phase purification of sulfur dioxide industrial waste gas, the specific contents are as follows:

1. The preparation steps of perfluorosulfonic acid/manganese oxide/polytetrafluoroethylene composite ion exchange membrane are as follows:

(1) Add an equal volume mass percentage concentration of 1% surfactant solution (Triton X-100) to the perfluorosulfonic acid solution with a mass percentage concentration of 5% to mix, stir, and sonicate to make it evenly distributed;

(2) Mix manganese oxide powder, tetraethyl orthosilicate, absolute ethanol and sulfuric acid at a mass ratio of 0.3:1.5:5:0.1, stir at high speed for 24 hours to form a manganese oxide sol, add the sol to prepare In the perfluorosulfonic acid solution of equal quality, obtain perfluorosulfonic acid/manganese oxide solution;

(3) Wash the polytetrafluoroethylene porous membrane with ethanol and deionized water, dry it, soak it in isopropanol for 24 hours and dry it;

(4) Soak the polytetrafluoroethylene porous membrane in step (3) in perfluorosulfonic acid/manganese oxide solution for 24 hours, take it out, roll it, dry it at 120°C, then soak it and roll it again for 5 times, that is A perfluorosulfonic acid/manganese oxide/polytetrafluoroethylene composite ion exchange membrane is obtained.

2. Use perfluorosulfonic acid/manganese oxide/polytetrafluoroethylene composite ion-exchange membrane as a device for ion-exchange membrane electrodialysis and liquid phase purification of sulfur dioxide industrial waste gas, with the same structure as in Example 1;

3. At room temperature, the device uses water with a conductivity (25°C) less than 1mS/m and a pH value of 7 as the absorbing liquid, adding ferrous sulfate as the active catalyst, and the water and catalyst are configured according to the mass ratio of 10:1. The absorption liquid of low-concentration sulfur dioxide flue gas is directly put into the cathode chamber of the electrodialyzer, and under the condition of a voltage of 2V, the waste gas with a flow rate of 5000ml/min and a sulfur dioxide concentration of 2000ppm is passed into the electrodialysis reactor. During the mixed flow process with the cathode chamber, _SO2 is absorbed and oxidized, and the sulfuric acid with a lower concentration generated in the cathode chamber enters the anode chamber through the ion exchange membrane to be concentrated under the action of an electric field, and part of the sulfurous acid that is not completely oxidized is also in the anode chamber The electrochemical oxidation is sulfuric acid, and the treated gas is purified gas.

During the absorption process of low-concentration sulfur dioxide, the current density between the two electrodes is kept at 5A/m ² , the purified flue gas is discharged from the outlet of the absorption tower, and the concentration of sulfur dioxide in the outlet gas is kept below 150ppm; through electrochemical ion membrane dialysis Finally, the concentration of sulfate radicals in the absorption liquid decreases, and the barren liquid after dialysis is reused in the purification and absorption process, so that the absorption liquid of the reactor can continuously purify sulfur dioxide. The sulfuric acid concentration in the electrodialyzer anolyte storage tank increases with the dialysis time, and after 24 hours of continuous treatment, the sulfuric acid concentration in the anolyte storage tank can reach 40%.

In the initial stage of the reactor, water absorbs sulfur dioxide to generate sulfurous acid, and sulfurous acid is catalyzed by manganese oxide to be oxidized to sulfuric acid. When the reaction is close to saturation, that is, when the concentration of sulfur dioxide at the outlet of the absorption tower begins to rise, usually after 120 minutes of reaction, the power is turned on for dialysis. Simultaneously start the anolyte circulation.

After the electrodialysis reaction, the sulfate radical in the absorption solution migrates to the anode chamber through the ion exchange membrane, and the concentration of the absorption solution in the cathode chamber decreases. Maintain continuous absorption capacity for sulfur dioxide. In the anode compartment, at the beginning, the concentration of sulfuric acid in the anolyte increases with the lapse of dialysis time. After 24 hours of treatment, the concentration of sulfuric acid in the anolyte can reach 40%. Slowly inject pure water at a flow rate of 1 min so that the concentration of sulfuric acid after dialysis is stabilized at 40%, that is, sulfuric acid with a concentration of 40% can be produced at a rate of 1L/min.

Claims (6)

1. a method for liquid phase purification industrial SO 2 waste gas is worked in coordination with in electrodialysis, it is characterized in that: be absorbing liquid with water, and adding transition metal salt as active catalyst, under voltage is 0.5 ~ 6V condition, is 20 ~ 5000ml/min, SO by flow velocity ₂concentration is that the waste gas of 50 ~ 5000ppm passes into electrodialysis reactor, SO in the mixed flow process of solarization air cell and cathode chamber ₂absorbed and be oxidized, the sulfuric acid that the concentration generated is lower enters anode chamber by amberplex by cathode chamber and is concentrated under electric field action, the sulfurous acid that part is not fully oxidized also enters anode chamber and is electrochemically oxidized as sulfuric acid, and after process, gas is Purge gas.

2. the method for liquid phase purification industrial SO 2 waste gas is worked in coordination with in electrodialysis according to claim 1, it is characterized in that: transition metal salt is Fe ³⁺, Mn ³⁺, Fe ²⁺, Mn ²⁺, Co ²⁺, Ni ²⁺, Zn ²⁺one in salt, concentration is 0.001 ~ 1mol/L.

3. the method for liquid phase purification industrial SO 2 waste gas is worked in coordination with in electrodialysis according to claim 1 and 2, it is characterized in that: amberplex is perfluorinated sulfonic acid/manganese oxide/polytetrafluoroethylene (PTFE) cluster ion exchange membrane, and this amberplex prepares as follows:

(1) at mass percent concentration be 5% perfluorinated sulfonic acid solution in add equal-volume mass percent concentration 0.1 ~ 1% surfactant solution mixing, stir, ultrasonic to make it be uniformly distributed;

(2) by manganese oxide powder, ethyl orthosilicate, absolute ethyl alcohol and sulfuric acid be in mass ratio 0.1:1:5:0.1 ~ 0.3:2:5:0.1 ratio mixing, high-speed stirred 10 ~ 24 hours, form manganese oxide colloidal sol, this colloidal sol is added configure etc. quality perfluorinated sulfonic acid solution in, obtain perfluorinated sulfonic acid/manganese oxide solution;

(3) soak 12 ~ 24h by putting into isopropyl alcohol after polytetrafluoroethylporous porous membrane ethanol and washed with de-ionized water, oven dry and dry;

(4) polytetrafluoroethylporous porous membrane of step (3) is put into perfluorinated sulfonic acid/manganese oxide solution and soak 24 ~ 48h, roll extrusion after taking out, 120 DEG C of oven dry, and then soak roll extrusion more so 4 ~ 5 times repeatedly, namely obtain perfluorinated sulfonic acid/manganese oxide/polytetrafluoroethylene (PTFE) cluster ion exchange membrane.

4. the method for liquid phase purification industrial SO 2 waste gas is worked in coordination with in electrodialysis according to claim 3, it is characterized in that: surfactant is Triton X-100.

5. realize the device that the method for liquid phase purification industrial SO 2 waste gas is worked in coordination with in electrodialysis according to claim 1, it is characterized in that: it comprises electrodialysis chamber, power supply, wherein electrodialysis chamber is cylindrical hermetic chamber, electrodialysis chamber is divided into solarization air cell of lower floor (9) by lower clapboard (13) and upper spacer (17), middle level reative cell (14), upper strata separation chamber (20), aeration sieve plate (12) is arranged on lower clapboard (13) below, solarization air cell of lower floor top is provided with catholyte entrance (8) and is positioned at aeration sieve plate (12) top, solarization air cell of lower floor bottom is provided with gaseous mixture entrance (11) and is positioned at aeration sieve plate (12) below, side, upper strata separation chamber is provided with catholyte outlet (3), and top, upper strata separation chamber is provided with clean gas outlet (19), positive plate (6), amberplex (5) and minus plate (4) spiral winding are in the reative cell of middle level, amberplex (5) is arranged between minus plate (4) and positive plate (6), gap between amberplex and minus plate forms cathode chamber, positive plate and the intermembranous formation anode chamber, gap of ion-exchange, lower clapboard (13) have reative cell catholyte entrance (7) and be communicated with cathode chamber, upper spacer (17) has reative cell catholyte outlet (15) and is communicated with cathode chamber, anolyte entrance (10) and anolyte outlet (18) are separately positioned on electrodialysis chamber bottom with top and are communicated with anode chamber, cathode column (1) is connected with minus plate (4), anode posts (16) is connected with positive plate (6), cathode column (1) is connected with power cathode, anode posts (16) is connected with positive source.

6. device according to claim 5, is characterized in that: minus plate is stainless steel electrode plate, and positive plate is titanium or titanium plating metallio-oxide electrode plate.