阅读说明：本技术 一种利用离子置换电膜反应器制备碳酸氢钠的方法 (Method for preparing sodium bicarbonate by using ion exchange membrane reactor ) 是由 徐铜文 王皝莹 汪耀明 于 2021-09-24 设计创作，主要内容包括：本发明公开了一种利用离子置换电膜反应器制备碳酸氢钠的方法,包括：以制钒工业中产生的废气二氧化碳和废盐硫酸钠作为原料,将二氧化碳制成碳酸溶液并与硫酸钠溶液分别加入到离子置换电膜反应器的不同料液室,在电场的作用下,碳酸电离出来的碳酸氢根离子经过阴离子交换膜,与硫酸钠溶液中通过阳离子交换膜的钠离子结合,在碱室形成碳酸氢钠溶液。本发明提供了一种新颖的方法制备碳酸氢钠,有效地将温室气体二氧化碳引入,不仅有利于降低空气中二氧化碳浓度、缓解温室效应,而且降低了碳酸氢钠生产能耗,提高了生产效率。(The invention discloses a method for preparing sodium bicarbonate by using an ion exchange membrane reactor, which comprises the following steps: the method comprises the steps of taking waste gas carbon dioxide and waste salt sodium sulfate generated in the vanadium production industry as raw materials, preparing carbon dioxide into a carbonic acid solution, respectively adding the carbonic acid solution and the sodium sulfate solution into different material liquid chambers of an ion exchange membrane reactor, and under the action of an electric field, allowing bicarbonate ions ionized by carbonic acid to pass through an anion exchange membrane and be combined with sodium ions in the sodium sulfate solution through a cation exchange membrane to form a sodium bicarbonate solution in an alkali chamber. The invention provides a novel method for preparing sodium bicarbonate, which effectively introduces greenhouse gas carbon dioxide, is beneficial to reducing the concentration of carbon dioxide in the air and relieving the greenhouse effect, reduces the production energy consumption of sodium bicarbonate and improves the production efficiency.)

1. A method for preparing sodium bicarbonate by adopting an ion exchange membrane reactor is characterized by comprising the following steps:

the ion exchange membrane reactor consists of a reactor membrane stack, and an anode plate and a cathode plate which are arranged on two sides of the reactor membrane stack; the reactor membrane stack is composed of anion exchange membranes and cation exchange membranes which are alternately arranged and added with a flow passage separation net and a sealing gasket; an anode chamber is formed between the anode plate and the adjacent anion exchange membrane, and a cathode chamber is formed between the cathode plate and the adjacent cation exchange membrane; forming one or more repeating units of 'feed chamber 1-alkali chamber-feed chamber 2' in the electrodialysis membrane stack; the anode chamber and the cathode chamber are respectively communicated with a polar chamber liquid storage tank, the material liquid chamber 1 is communicated with a sodium sulfate solution storage tank, the material liquid chamber 2 is communicated with a carbonic acid solution storage tank, and the alkali chamber is communicated with an alkali chamber liquid storage tank; under the drive of a peristaltic pump, feed liquid in the anode chamber, the cathode chamber, the feed liquid chamber 1, the feed liquid chamber 2 and the alkali chamber forms circulating flow between the ion exchange membrane reactor and a connected storage tank;

the method for preparing the sodium bicarbonate by using the ion exchange membrane reactor comprises the following steps:

(1) installing a bubble bottle filled with pure water or polyethyleneimine solution on a bubble machine, and pumping carbon dioxide in a gas tank into the bubble bottle through the bubble machine to obtain a carbonic acid solution with the pH of 3.8-4.0 or 6.5-8.5;

the bubble bottle filled with the carbonic acid solution is used as a carbonic acid solution storage tank to be communicated with the feed liquid chamber 2;

(2) introducing the sodium sulfate solution filled in a sodium sulfate solution storage tank into a material liquid chamber 1 of an ion exchange membrane reactor device, introducing the carbonic acid solution obtained in the step (1) into a material liquid chamber 2, introducing pure water filled in an alkaline chamber liquid storage tank into an alkaline chamber, and introducing an electrode chamber liquid filled in an electrode chamber liquid storage tank into an anode chamber and a cathode chamber;

(3) connecting an anode plate and a cathode plate of the ion exchange membrane reactor with an external power supply, applying constant current, controlling the flow rate of feed liquid in all chambers to be 2-5 cm/s and controlling the current density to be 2-6 mA/cm²Producing sodium bicarbonate;

under the action of an electric field, bicarbonate ions ionized from the carbonic acid solution enter the alkali chamber through an anion exchange membrane, sodium ions in the sodium sulfate solution enter the alkali chamber through a cation exchange membrane, and the bicarbonate ions are combined with the sodium ions, so that the sodium bicarbonate solution is formed in the alkali chamber.

2. The method of claim 1, wherein: conductivity sensors are arranged in the alkali chamber and the feed liquid chamber 1, and a pH sensor is arranged in the feed liquid chamber 2.

3. The method according to claim 1 or 2, characterized in that: in the production process, the pH of the carbonic acid solution in the feed chamber 2 is monitored by a pH sensor, and the pH of the carbonic acid solution is maintained at 3.8-4.0 or 6.5-8.5 by supplementing carbon dioxide.

4. The method according to claim 1 or 2, characterized in that: during production, the conductivity in the feed chamber 1 is monitored by a conductivity sensor and when it drops below 10ms/cm, production is terminated.

5. The method of claim 1, wherein: the cation exchange membrane is CMX manufactured by Astom corporation of Japan, and the anion exchange membrane is AMX manufactured by Astom corporation of Japan.

6. The method of claim 1, wherein: the mass concentration of the polyethyleneimine solution is 2-8%, and the molecular weight of the polyethyleneimine is 600-10000.

7. The method of claim 1, wherein: the concentration of the sodium sulfate solution filled in the sodium sulfate solution storage tank is 0.1-0.3 mol/L.

8. The method of claim 1, wherein: the polar solution is a sodium sulfate solution with the concentration of 0.1-0.3 mol/L.

9. The method of claim 1, wherein: the carbon dioxide and the sodium sulfate are derived from waste gas carbon dioxide and waste salt sodium sulfate generated in the vanadium production industry.

Technical Field

The invention relates to an ion exchange membrane reactor system for sodium bicarbonate production and a production method thereof.

Background

Over the past half century, the rise in atmospheric carbon dioxide concentrations from 280ppm to 406ppm has caused a global rise in temperature of 1 ℃, making the greenhouse effect the most global concern for the environment. According to the signed Paris Agreement regulations, there is a demand for global greenhouse gases to achieve zero emissions before the end of the century. Reducing carbon dioxide emissions is therefore an important goal.

CCS is considered as an important way to reduce carbon dioxide emissions and achieve carbon recycling, and it is divided into two processes, carbon capture and separation. Carbon capture is considered the most costly process in CCS, and therefore reducing carbon dioxide capture costs is a necessary approach to reduce energy consumption. The non-chemical carbon dioxide capture method mainly comprises various methods such as chemical absorption, physical adsorption, membrane adsorption and the like. From a cost and capacity perspective, chemical absorption is considered to be the most promising carbon dioxide capture method.

The chemical adsorbents commonly used are mainly alkaline amine solutions and inorganic base solutions. The energy consumption of the alkanolamine and potassium carbonate solution for capturing carbon dioxide is 0.83-1.11 kWh/kg, and the energy consumption of the alkali solution such as sodium hydroxide for capturing carbon dioxide is 2.4 kWh/kg. The patent CN112791707A prepares the composite material by loading organic amine or organic alcohol amine substances, and finds that the adsorption quantity of the material to carbon dioxide gas is obviously enhanced. Electrochemical capture of carbon dioxide is suitable for all situations, without the need for external energy sources (heat, high pressure) and without the need for adsorbent materials, as opposed to non-chemical capture. An additional advantage of electrochemical capture of carbon dioxide is the ability to integrate the capture and utilization of carbon dioxide. At present, the carbon dioxide needs to be directly captured at 0.98kWh/kg, and the energy consumption for regenerating the carbon dioxide by bipolar membrane electrodialysis can be 0.58kWh/kg at least at present. In the process of electrically reducing carbon dioxide, 13.9kWh/kg is required for the conversion of carbon dioxide into methanol, and more energy is consumed. Therefore, the search for a high-activity selective catalyst, the improvement of faraday efficiency and the improvement of effective carbon dioxide conversion rate are key challenges for carbon dioxide electrocatalytic reduction.

The largest carbon dioxide emissions are also due to the combustion of fossil fuels, such as industrial vanadium production. Roasting leaching and direct leaching are commonly used in industry for extracting vanadium. Sodium roasting is the most mature vanadium extraction process, and mainly uses sodium salts, such as sodium carbonate, sodium sulfate, sodium chloride and the like, to convert vanadium slag or vanadium titano-magnetite into water-soluble or acid-soluble sodium vanadate through high-temperature roasting, and after ammonium sulfate is used to precipitate vanadate, refined vanadium products are obtained through sintering. A large amount of sodium sulfate is generated after the vanadium precipitation and deamination, the large amount of sodium sulfate is stockpiled, and the treatment cost of waste gas carbon dioxide generated in the whole process is high, so that the recycling is difficult to realize. To improve the economic utilization of carbon dioxide, the captured carbon dioxide can be converted into valuable products.

Patent CN112919502A also describes a method for producing food grade sodium bicarbonate by double decomposition, mainly by recycling ammonium chloride and sodium chloride contained in the mother liquor generated in the production process of sodium bicarbonate. At present, the most mature method in industry is to produce high-quality sodium carbonate and sodium bicarbonate by using carbon dioxide as a raw material by using a synthesis method. The synthesis method comprises an ammonia-soda process and a combined soda process, wherein ammonia gas and carbon dioxide are introduced into saturated salt water to react to form sodium bicarbonate and ammonium chloride, and then carbon dioxide is introduced into sodium carbonate obtained by heating sodium bicarbonate to obtain high-purity sodium bicarbonate. Compared with the ammonia-soda process for producing sodium bicarbonate with energy consumption of 4.8kWh/kg, the combined-soda process not only needs energy consumption of 3.6kWh/kg, but also reduces the pollution to the environment while improving the utilization rate of sodium chloride. But the energy consumption is still too high for the production of sodium bicarbonate.

In order to achieve the purposes of reducing the emission of carbon dioxide and reducing the energy consumption for producing sodium bicarbonate, an ion replacement electric membrane technology with high current efficiency, low energy consumption and zero emission can be adopted. The ion replacement electric membrane reaction is a technology that anion-cation exchange membranes are alternately arranged, and anion and cation of two different substances are mutually exchanged to obtain two new salts, and is commonly used in the aspects of chlorine-free potash fertilizer production, salt-containing wastewater softening, clean production of partial organic acid salt and the like. Therefore, the waste salt sodium sulfate and carbon dioxide generated in the vanadium production industry can be converted into sodium bicarbonate and sulfuric acid with commercial value by adopting an ion replacement electric membrane reaction method.

Disclosure of Invention

In view of the above, the present invention aims to provide a method for preparing sodium bicarbonate by using an ion exchange membrane reactor, so as to capture carbon dioxide and utilize waste sodium sulfate, and convert the waste sodium sulfate into a high value-added product.

In order to solve the problems, the invention adopts the following technical scheme:

a method for preparing sodium bicarbonate by adopting an ion exchange membrane reactor is characterized by comprising the following steps:

the ion exchange membrane reactor consists of a reactor membrane stack, and an anode plate and a cathode plate which are arranged on two sides of the reactor membrane stack; the reactor membrane stack is composed of anion exchange membranes and cation exchange membranes which are alternately arranged and added with a flow passage separation net and a sealing gasket; an anode chamber is formed between the anode plate and the adjacent anion exchange membrane, and a cathode chamber is formed between the cathode plate and the adjacent cation exchange membrane; forming one or more repeating units of 'feed chamber 1-alkali chamber-feed chamber 2' in the electrodialysis membrane stack; the anode chamber and the cathode chamber are respectively communicated with a polar chamber liquid storage tank, the material liquid chamber 1 is communicated with a sodium sulfate solution storage tank, the material liquid chamber 2 is communicated with a carbonic acid solution storage tank, and the alkali chamber is communicated with an alkali chamber liquid storage tank; under the drive of a peristaltic pump, feed liquid in the anode chamber, the cathode chamber, the feed liquid chamber 1, the feed liquid chamber 2 and the alkali chamber forms circulating flow between the ion exchange membrane reactor and a connected storage tank; conductivity sensors are arranged in the alkali chamber and the feed liquid chamber 1, and a pH sensor is arranged in the feed liquid chamber 2.

The method for preparing the sodium bicarbonate by using the ion exchange membrane reactor comprises the following steps:

(1) installing a bubble bottle filled with pure water or a polyethyleneimine solution on a bubble machine, and pumping carbon dioxide in a gas tank into the bubble bottle through the bubble machine to obtain a carbonic acid solution with the pH of 3.8-4.0 (when the carbonic acid solution is prepared by pure water) or 6.5-8.5 (when the carbonic acid solution is prepared by the polyethyleneimine solution);

the bubble bottle filled with the carbonic acid solution is used as a carbonic acid solution storage tank to be communicated with the feed liquid chamber 2;

(2) introducing the sodium sulfate solution filled in a sodium sulfate solution storage tank into a material liquid chamber 1 of an ion exchange membrane reactor device, introducing the carbonic acid solution obtained in the step (1) into a material liquid chamber 2, introducing pure water filled in an alkaline chamber liquid storage tank into an alkaline chamber, and introducing an electrode chamber liquid filled in an electrode chamber liquid storage tank into an anode chamber and a cathode chamber;

(3) connecting an anode plate and a cathode plate of the ion exchange membrane reactor device with an external power supply, applying constant current, controlling the flow rate of feed liquid in all chambers to be 2-5 cm/s and controlling the current density to be 2-6 mA/cm²Producing sodium bicarbonate;

under the action of an electric field, bicarbonate ions ionized from the carbonic acid solution enter the alkali chamber through an anion exchange membrane, sodium ions in the sodium sulfate solution enter the alkali chamber through a cation exchange membrane, and the bicarbonate ions are combined with the sodium ions, so that the sodium bicarbonate solution is formed in the alkali chamber.

During the production process, monitoring the pH of the carbonic acid solution in the feed chamber 2 through a pH sensor, and maintaining the pH of the carbonic acid solution at 3.8-4.0 (when the carbonic acid solution is prepared by pure water) or 6.5-8.5 (when the carbonic acid solution is prepared by polyethyleneimine solution) by supplementing carbon dioxide;

during production, the conductivity in the feed chamber 1 is monitored by a conductivity sensor and when it drops below 10ms/cm, production is terminated.

Further, the cation exchange membrane is CMX manufactured by Astom corporation, japan, and the anion exchange membrane is AMX manufactured by Astom corporation, japan. .

Further, the mass concentration of the polyethyleneimine solution is 2-8%, and the molecular weight of the polyethyleneimine is 600-10000.

Further, the concentration of the sodium sulfate solution charged into the sodium sulfate solution tank is 0.1 to 0.3 mol/L.

Furthermore, the polar solution is a sodium sulfate solution with the concentration of 0.1-0.3 mol/L.

Further, the used carbon dioxide and the used sodium sulfate are derived from waste gas carbon dioxide and waste salt sodium sulfate generated in the vanadium production industry.

Compared with the prior art, the invention has the beneficial effects that:

1. the invention uses the waste gas carbon dioxide and waste salt sodium sulfate generated in the vanadium production industry, which not only effectively reduces the emission of carbon dioxide and relieves the greenhouse effect, but also changes waste into valuable, converts the waste into sodium bicarbonate products with high added value, and realizes low-carbon circulation and waste utilization.

2. The invention utilizes the ion exchange membrane reactor, has the advantages of high current efficiency, low energy consumption and the like, can convert two different feed liquids into two products, greatly reduces the production cost, and realizes the greenization and atom economy of the chemical process.

3. Compared with the sodium bicarbonate produced by an industrially adopted synthesis method, the sodium bicarbonate product produced by the invention greatly reduces the energy consumption for producing the sodium bicarbonate and improves the economical efficiency of the process.

4. The invention adopts a bubble machine which is sold in the market and is provided with a carbon dioxide gas tank, the device is portable, and the carbon dioxide gas can be pressed into pure water under the action of about 7 atmospheric pressures, so that the solubility of the carbon dioxide gas in the pure water is increased, and the concentration of bicarbonate ions is increased; and the polyethyleneimine solution is adopted to adsorb the carbon dioxide, wherein the tertiary amine reacts with the carbon dioxide to produce bicarbonate radical, so that the conductance of the carbonate chamber is increased, and the concentration of bicarbonate radical ions is improved.

Drawings

FIG. 1 is a schematic diagram of a membrane stack of an ion exchange membrane reactor according to the present invention;

FIG. 2 is a schematic diagram showing the variation of the sodium bicarbonate concentration in examples 1 to 3 of the present invention;

FIG. 3 is a schematic diagram of the current efficiency and energy consumption of sodium bicarbonate in examples 1 to 3 of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The ion exchange membrane reactor adopted in the following embodiment consists of a reactor membrane stack, and an anode plate and a cathode plate which are arranged at two sides of the reactor membrane stack; as shown in fig. 1, the reactor membrane stack is composed of anion exchange membranes and cation exchange membranes which are alternately arranged and are added with flow passage separation nets and sealing gaskets; an anode chamber is formed between the anode plate and the adjacent anion exchange membrane, and a cathode chamber is formed between the cathode plate and the adjacent cation exchange membrane; one or more repeated units of 'feed chamber 1-alkali chamber-feed chamber 2' are formed in the electrodialysis membrane stack (one unit is used for the electrodialysis membrane stack of the following example); the anode chamber and the cathode chamber are respectively communicated with a polar chamber liquid storage tank, the material liquid chamber 1 is communicated with a sodium sulfate solution storage tank, the material liquid chamber 2 is communicated with a carbonic acid solution storage tank, and the alkali chamber is communicated with an alkali chamber liquid storage tank; under the drive of the peristaltic pump, the feed liquid in the anode chamber, the cathode chamber, the feed liquid chamber 1, the feed liquid chamber 2 and the alkali chamber forms circulating flow between the ion exchange membrane reactor device and the connected storage tank. Conductivity sensors are arranged in the alkali chamber and the feed liquid chamber 1, and a pH sensor is arranged in the feed liquid chamber 2.

Each chamber is separated by a silica gel partition, the cation exchange membrane is a CMX membrane produced by Astom corporation of Japan, the anion exchange membrane is an AMX membrane produced by Astom corporation of Japan, and the effective area of each membrane is 189cm²(21*9cm²) And the thickness of the silica gel clapboard is 0.8 mm.

The bubble machine used in the examples described below was purchased from Wikiosks electronic commerce, Inc., of Foshan.

The carbon dioxide and sodium sulfate used in the following examples are derived from waste gas carbon dioxide and waste salt sodium sulfate generated in the vanadium production industry.

Example 1

In this embodiment, the steps of preparing sodium bicarbonate by using the above ion exchange membrane reactor are as follows:

(1) and (3) installing the bubble bottle filled with 500mL of pure water on a bubble machine, and driving carbon dioxide in the gas tank into the bubble bottle under the action of a certain pressure through the bubble machine to obtain 500mL of carbonic acid solution with the pH value of 3.8-4.0.

The bubble bottle filled with the carbonic acid solution is used as a carbonic acid solution storage tank to be communicated with the feed chamber 2.

(2) And (2) introducing 500mL of 0.1mol/L sodium sulfate solution filled in a sodium sulfate solution storage tank into a material liquid chamber 1 of the ion exchange membrane reactor device, introducing the carbonic acid solution obtained in the step (1) into a material liquid chamber 2, introducing 500mL of pure water filled in an alkaline chamber liquid storage tank into an alkaline chamber, and introducing 500mL of 0.1mol/L sodium sulfate solution filled in an electrode chamber liquid storage tank into the anode chamber and the cathode chamber.

(3) Connecting the anode plate and the cathode plate of the ion exchange membrane reactor device with an external power supply, applying constant current, controlling the flow rate of feed liquid in all chambers to be 3cm/s and controlling the current density to be 2mA/cm²And producing sodium bicarbonate. In the production process, the pH of the solution in the feed liquid chamber 2 is monitored by a pH sensor, and carbon dioxide is supplemented by an external carbon dioxide gas pipe, so that the pH is maintained at about 3.8.

After the reaction is carried out for 150min, the concentration of the produced alkali is 0.058mol/L, the current efficiency is 79 percent, and the energy consumption is 3.6 kWh/kg.

Example 2

This example was carried out in the same manner as in example 1 except that the current density in step (3) was controlled to 4mA/cm²。

After the reaction is carried out for 150min, the concentration of the produced alkali is 0.09mol/L, the current efficiency is 64 percent, and the energy consumption is 11.5 kWh/kg.

Example 3

This example was carried out in the same manner as in example 1 except that the current density in step (3) was controlled to 6mA/cm²。

After the reaction is carried out for 150min, the concentration of the produced alkali is 0.14mol/L, the current efficiency is 66 percent, and the energy consumption is 18.5 kWh/kg.

Example 4

In this embodiment, the steps of preparing sodium bicarbonate by using the above ion exchange membrane reactor are as follows:

(1) a bubble vial containing 500mL of a polyethyleneimine solution having a concentration of 2 wt% (polyethyleneimine having a molecular weight of 1200) was set in a bubble machine, and carbon dioxide in the vial was pumped into the bubble vial by the bubble machine under a constant pressure to obtain 500mL of a bicarbonate ion-containing carbonic acid chamber solution having a pH of 6.5.

The bubble bottle containing the carbonic acid chamber solution is used as a carbonic acid solution storage tank to be communicated with the feed chamber 2.

(2) And (2) introducing 500mL of 0.1mol/L sodium sulfate solution filled in a sodium sulfate solution storage tank into a material liquid chamber 1 of the ion exchange membrane reactor device, introducing the carbonic acid chamber solution obtained in the step (1) into a material liquid chamber 2, introducing 500mL of pure water filled in an alkaline chamber solution storage tank into an alkaline chamber, and introducing 500mL of 0.1mol/L sodium sulfate solution filled in an electrode chamber solution storage tank into the anode chamber and the cathode chamber.

(3) Connecting the anode plate and the cathode plate of the ion exchange membrane reactor device with an external power supply, applying constant current, controlling the flow rate of feed liquid in all chambers to be 3cm/s and controlling the current density to be 4mA/cm²And producing sodium bicarbonate. In the production process, the pH of the solution in the feed liquid chamber 2 is monitored by a pH sensor, and carbon dioxide is supplemented by an external carbon dioxide gas pipe, so that the pH is maintained at about 6.5.

After the reaction is carried out for 150min, the concentration of the produced alkali is 0.104mol/L, the current efficiency is 74 percent, and the energy consumption is 3.8 kWh/kg.

Example 5

This example was carried out in the same manner as in example 4 except that the concentration of the polyethyleneimine solution in step (1) was 4 wt%.

After the reaction is carried out for 150min, the concentration of the produced alkali is 0.11mol/L, the current efficiency is 78 percent, and the energy consumption is 3.7 kWh/kg.

Example 6

This example was carried out in the same manner as in example 4 except that the concentration of the polyethyleneimine solution in step (1) was 8 wt%.

After the reaction is carried out for 150min, the concentration of the produced alkali is 0.11mol/L, the current efficiency is 78 percent, and the energy consumption is 3.2 kWh/kg.

Example 7

This example was carried out in the same manner as in example 6 except that the molecular weight of polyethyleneimine in step (1) was 600.

After the reaction is carried out for 150min, the concentration of the produced alkali is 0.11mol/L, the current efficiency is 78 percent, and the energy consumption is 10.7 kWh/kg.

Example 8

This example was carried out in the same manner as in example 6 except that the molecular weight of polyethyleneimine in step (1) was 1800.

After the reaction is carried out for 150min, the concentration of the produced alkali is 0.124mol/L, the current efficiency is 88 percent, and the energy consumption is 1.2 kWh/kg.

Example 9

This example was carried out in the same manner as in example 6 except that the molecular weight of polyethyleneimine in step (1) was 10000.

After the reaction is carried out for 150min, the concentration of the produced alkali is 0.1mol/L, the current efficiency is 71 percent, and the energy consumption is 1.2 kWh/kg.

Comparative examples 1 to 3 show that: with the increase of the current density, the alkali-producing concentration is greatly increased, because the increase of the electric field can accelerate the migration rate of ions, so that more bicarbonate ions enter the alkali chamber, but the increase of the electric field also obviously increases the energy consumption.

Comparing example 2 with example 4, it can be seen that: the addition of polyethyleneimine molecules can effectively increase the conductivity of the solution, so that the energy consumption of the membrane stack is obviously reduced; and the polyethyleneimine can improve the absorption of carbon dioxide molecules, so that the concentration of sodium bicarbonate is slightly increased, because the concentration of the polyethyleneimine solution is 2 wt%, the concentration is lower, and the concentration for absorbing carbon dioxide is not high.

Comparative examples 4 to 6 show that: the concentration of sodium bicarbonate can be increased and the energy consumption of the membrane stack can be reduced with the increase of the concentration of polyethyleneimine, but the ion migration rate is limited due to the lower current density, so that the further increase of the alkali concentration is slowed down.

Comparative examples 6 to 9 show that: the concentration of the sodium bicarbonate is not obviously improved by the polyethyleneimine solutions with the same mass concentration and different molecular weights, but the energy consumption is greatly reduced along with the increase of the molecular weight, because the membrane pollution is formed when the molecular weight is 600, the integral energy consumption of the membrane stack is increased. And when the molecular weight of the polyethyleneimine is 10000, the coiled structure of the molecule reduces the reaction of active sites and carbon dioxide, so that the energy consumption is the same as that of the molecular weight of 1800.

The embodiments show that the invention provides a method for preparing sodium bicarbonate by adopting an ion exchange membrane reactor, and the method can improve the concentration of the sodium bicarbonate and reduce the energy consumption by optimizing different conditions, can realize the production of the sodium bicarbonate, and can effectively reduce the energy consumption of the production, thereby not only providing a new idea for industrial production of the sodium bicarbonate, but also greatly reducing the energy consumption, leading the process of producing the sodium bicarbonate to be more economic and environment-friendly, and being more suitable for industrial popularization and application.