A testing device and testing method for carbon dioxide permeability of a permeable membrane

Abstract

The application discloses a testing device and a testing method for carbon dioxide permeability of a permeation membrane. The testing device comprises a sample feeding system for feeding and processing a standard solution, a membrane cell system for installing a gas permeation membrane, and a measurement and circulation system for self-cleaning and measuring conductivity. The sample feeding system delivers a sodium carbonate standard solution through a syringe pump and injects phosphoric acid through an acid agent syringe pump to acidify the standard solution to release carbon dioxide. The membrane cell system clamps the membrane to be tested between an upstream chamber and a downstream chamber to simulate a liquid-liquid separation environment. The measurement and circulation system continuously monitors the conductivity change of the downstream solution through a sensor and combines a self-cleaning circuit to ensure measurement accuracy. The testing method indirectly calculates the carbon dioxide permeation flux and permeability based on the conductivity change. The application can realize high sensitivity, low cost and simple operation of the permeation membrane carbon dioxide permeability test in a liquid-liquid environment, and solves the problem of working condition simulation distortion of the existing gas-gas phase testing device.

Description

Technical Field

[0001] This invention relates to the field of membrane separation technology and characterization, and particularly to a testing device and method for measuring the carbon dioxide permeability of a permeable membrane. Specifically, it is a device and method for indirectly measuring carbon dioxide permeability using conductivity under conditions where both sides of the membrane are in a liquid environment. Background Technology

[0002] Membrane technology is a core component of gas separation, with carbon dioxide separation membranes playing a crucial role in carbon capture, greenhouse gas emission reduction, and separation in chemical processes. Accurate laboratory-scale testing techniques and the ability to simulate real-world operating conditions are indispensable for the accurate evaluation and screening of high-performance membrane materials.

[0003] Currently, research on the testing of carbon dioxide permeability of permeable membranes mainly focuses on calculating membrane permeability and selectivity by measuring the rate of increase of gas pressure on the permeate side or by analyzing the composition of the permeate gas using gas chromatography in a gas phase environment (gas-gas or gas-liquid system). However, in many cutting-edge applications, permeable membranes operate in a liquid-liquid environment, which leads to limitations in existing measurement methods, such as distortion of operating conditions and inapplicability of detection technologies.

[0004] Conductivity is a common technique for measuring the concentration of ions in a solution. When CO2 gas dissolves in water to form carbonic acid, it undergoes slight ionization to produce H+. + HCO 3- and CO3 2- Ions cause changes in the conductivity of the solution. This invention cleverly utilizes this principle to accurately deduce the CO2 permeation flux by monitoring changes in the conductivity of the absorbent. Summary of the Invention

[0005] To address the problems existing in the background art, the present invention provides a testing device and method for testing the carbon dioxide permeability of a permeable membrane.

[0006] The technical solution adopted in this invention is: The core of this method is to indirectly and accurately measure the amount of carbon dioxide permeating the membrane using the conductivity method.

[0007] I. A testing device for carbon dioxide permeability of a permeable membrane. It includes a sample introduction system, a membrane tank system, and a measurement and circulation system. The sample introduction system and the membrane tank system are connected by a main pipeline to provide the liquid reagents required for the test and to generate the carbon dioxide gas to be tested. The measurement and circulation system and the membrane tank system are connected by a pipeline to measure the carbon dioxide gas and to clean the membrane tank system.

[0008] The sample injection system includes a standard solution bottle, a first injection pump, an acid storage tank, a second injection pump, and a three-way valve; the main pipeline has two inlet ports and one outlet port, the two inlet ports being the first inlet port and the second inlet port; The standard solution bottle is connected to the first inlet of the main pipeline via a first injection pump, used to pump the liquid in the standard solution bottle into the main pipeline through the first inlet; the second injection pump is selectively connected to the acid storage tank or the second inlet of the main pipeline via the three-way valve, used to extract liquid from the acid storage tank or inject liquid into the main pipeline from the acid storage tank; the outlet of the main pipeline is connected to the membrane tank system; The liquid in the standard solution bottle and the liquid in the acid storage tank come into contact and react chemically to produce carbon dioxide.

[0009] The membrane tank system includes a membrane tank and a gas permeation membrane; The membrane tank is divided into an upper chamber and a lower chamber. The gas permeation membrane is sandwiched between the upper and lower chambers, forming independent upstream and downstream side chambers. Carbon dioxide gas permeates through the gas permeation membrane from the upstream side chamber to the downstream side chamber. The upstream side chamber is provided with an upstream liquid inlet / outlet, and the downstream side chamber is provided with a downstream liquid inlet / outlet. The upstream liquid inlet is connected to the outlet of the main pipeline. The upstream liquid outlet is used to discharge the reacted solution. Both the downstream liquid inlet and the downstream liquid outlet are connected to the circulation system.

[0010] The gas permeation membrane includes various polymer material membranes. When the polymer material membrane does not have the function of isolating water and / or ions, a breathable and hydrophobic protective layer that only allows carbon dioxide gas to pass through but blocks liquid and ions is added to the upstream side of the polymer material membrane. The material of the breathable and hydrophobic protective layer is polydimethylsiloxane.

[0011] The membrane tank system also includes a temperature detection unit, which is located in the downstream side chamber and is used to detect the liquid temperature in the downstream side chamber and provide temperature compensation; the inner surfaces of both the upstream side chamber and the downstream side chamber are provided with spiral flow channels.

[0012] The measurement and circulation system includes a conductivity sensor, a two-way valve, a magnetic pump, a flow choke, a water container, and an ion exchange resin tank. The water container is connected in sequence to the magnetic pump and the ion exchange resin tank, and then returns to the water container through the flow restrictor to form the first liquid circulation pipeline. The two-way valve is connected to the downstream liquid outlet of the downstream side chamber and is used to control the flow or stillness of the liquid flowing out of the downstream side chamber. The outlet of the ion exchange resin tank is connected to the downstream liquid inlet of the downstream side chamber. The downstream liquid outlet of the downstream side chamber is connected to the inlet of the water container through a two-way valve. When the two-way valve is open, the water container is connected to the magnetic pump, the ion exchange resin tank, and the downstream side chamber in sequence, and then returns to the water container through the two-way valve to form a second liquid circulation pipeline. The first liquid circulation pipeline and the second liquid circulation pipeline are both connected. When the two-way valve is closed, the first liquid circulation pipeline is connected, and the second liquid circulation pipeline is not connected. The conductivity sensor is also installed on the pipeline between the downstream side chamber and the two-way valve in the second liquid circulation pipeline. The conductivity sensor is used to monitor the conductivity of the liquid in the downstream side chamber.

[0013] The liquid in the standard solution bottle is a sodium carbonate solution, and the liquid in the acid storage tank is a phosphoric acid solution. The sodium carbonate solution and the phosphoric acid solution react in the main pipeline and the upstream chamber to generate carbon dioxide gas. The carbon dioxide gas permeates from the upstream chamber to the downstream chamber through the gas permeation membrane. The solution discharged from the upstream liquid outlet is a mixed solution of sodium carbonate solution and phosphoric acid solution after the chemical reaction.

[0014] The deionized water stored in the water container is purified by ion exchange resin to obtain ultrapure water for rinsing the downstream side chamber of the membrane tank, so that the conductivity of the liquid inside the downstream side chamber reaches the low level of ultrapure water. The carbon dioxide gas permeates from the upstream side chamber to the downstream side chamber after passing through the gas permeation membrane and dissolves into the ultrapure water. The conductivity of the ultrapure water liquid inside the downstream side chamber reaches a high level as the carbon dioxide gas content increases. The change in the carbon dioxide gas content that has permeated into the downstream side chamber can be obtained by detecting the change in conductivity.

[0015] II. A test method for a carbon dioxide permeability testing device used for permeable membranes. The testing method is as follows: The measurement and circulation system provides ultrapure water to flush the membrane tank system, reducing the conductivity of the liquid inside the membrane tank system to a low level. The sample introduction system provides various test liquids to the membrane tank system. These liquids react to generate carbon dioxide gas. The carbon dioxide gas permeates through the membrane from the upstream chamber to the downstream chamber and dissolves in the ultrapure water, thereby increasing the conductivity of the ultrapure water. By detecting the change in conductivity, the change in the amount of carbon dioxide gas permeating into the downstream chamber can be obtained.

[0016] The specific testing method is as follows: Step 1: Open the two-way valve to connect the second liquid circulation pipeline, start the magnetic pump to pump the deionized water stored in the water container into the ion exchange resin for purification to obtain ultrapure water. Then, the ultrapure water flows into the downstream side chamber of the membrane tank through the second liquid circulation pipeline until the conductivity reading of the ultrapure water flowing out of the downstream side chamber by the conductivity sensor stabilizes to the lowest value. Step 2: Switch the three-way valve to connect the second injection pump and the acid storage tank, and start the second injection pump to extract the phosphoric acid solution from the acid storage tank; after extraction is complete, switch the three-way valve to connect the acid injection pump to the main pipeline, and pump the extracted phosphoric acid solution into the main pipeline. Step 3: Start the first injection pump to pump the sodium carbonate solution from the standard solution bottle into the main pipeline, so that the sodium carbonate solution and phosphoric acid solution are mixed in the main pipeline and then introduced into the upstream chamber of the membrane cell and reacted to generate carbon dioxide gas. Step 4: Close the two-way valve and the second liquid circulation pipeline to allow the ultrapure water in the downstream chamber to stand still. The carbon dioxide gas generated in Step 3 will permeate from the upstream chamber through the gas permeation membrane to the downstream chamber. Record the changes in the conductivity sensor readings. Based on the conductivity change data and the quantitative relationship between conductivity change and carbon dioxide permeation, calculate the carbon dioxide permeation flux and permeability. Step 5: Repeat step 1 to prepare for the next test.

[0017] The beneficial effects of this invention are: This invention constructs a complete liquid-liquid separation testing environment, simulating the actual working condition where both sides of the membrane are liquid media. This solves the problem that traditional gas-gas or gas-liquid testing devices cannot accurately evaluate the true performance of membrane materials in liquid separation systems. Simultaneously, based on a high-precision conductivity sensor and a micro-injection pump, the conductivity method is used to detect dissolved carbon dioxide, which is extremely sensitive to changes in ion concentration and can detect permeate at extremely low concentrations, making it particularly suitable for evaluating high-performance membrane materials. This invention integrates an independent self-cleaning circulation loop, automatically performing deep cleaning and purification of the membrane tank and the entire liquid pipeline before and after testing. This effectively avoids reagent residues and cross-contamination, ensuring that each test begins with an extremely low and stable background conductivity. Its modular design facilitates maintenance and expansion, and the use of conventional conductivity detection instead of an expensive gas chromatograph significantly reduces the overall cost of the device, making it suitable for laboratory deployment. The method offers high testing sensitivity, ease of operation, and low cost in a liquid-liquid separation environment. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the carbon dioxide permeability testing device for a permeable membrane provided by the present invention. Figure 2 The conductivity-time curve is shown for the carbon dioxide permeability testing method for permeable membranes provided by this invention.

[0019] In the diagram: 100 - Sample injection system, 110 - Standard solution bottle, 120 - First injection pump, 130 - Acid storage tank, 140 - Second injection pump, 141 - Microsyringe, 150 - Three-way valve; 200 - Membrane tank system, 210 - Membrane tank, 211 - Upstream chamber, 212 - Downstream chamber, 220 - Gas permeation membrane, 230 - Temperature detection unit; 300 - Measurement and circulation system, 310 - Conductivity sensor, 320 - Two-way valve, 330 - Magnetic pump, 340 - Flow choke, 350 - Water container, 360 - Ion exchange resin tank. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] To enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0022] refer to Figure 1 , Figure 1 This is a schematic diagram of a device for testing the carbon dioxide permeability of a permeable membrane, provided by the present invention.

[0023] This invention provides a testing device for carbon dioxide permeability of a permeable membrane, comprising a sample introduction system 100 for providing and precisely controlling the liquid reagents required for the test, a membrane tank system 200 for installing the gas to be tested permeable membrane 220 and providing a liquid-liquid separation test environment, and a measurement and circulation system 300 for measuring and monitoring conductivity, transporting liquid, and realizing system self-cleaning. The sample introduction system 100 and the membrane tank system 200 are connected by a main pipeline to provide the liquid reagents required for the test and generate the carbon dioxide gas to be tested. The measurement and circulation system 300 and the membrane tank system 200 are connected by a pipeline to measure the carbon dioxide gas and clean the membrane tank system 200.

[0024] The sample injection system 100 includes a standard solution bottle 110, a first injection pump 120, an acid storage tank 130, a second injection pump 140, and a three-way valve 150; the main pipeline has two inlet ports and one outlet port, the two inlet ports being the first inlet port and the second inlet port; The standard solution bottle 110 is connected to the first inlet of the main pipeline via the first injection pump 120, and is used to pump the liquid sodium carbonate solution in the standard solution bottle 110 into the main pipeline at a constant flow rate through the first inlet; the second injection pump 140 is selectively connected to the acid storage tank 130 or the second inlet of the main pipeline via the three-way valve 150, and is used to extract or inject the liquid phosphoric acid solution in the acid storage tank 130 into the main pipeline at a minute and precise flow rate; the outlet of the main pipeline is connected to the membrane tank system 200; Specifically, the three-way valve 150 is installed on the pipeline to guide the mixing of acidic reagents and standard solutions, or to replenish acid to the acid injection pump in different operating modes.

[0025] The liquid sodium carbonate solution in standard solution bottle 110 and the liquid phosphoric acid solution in acid storage tank 130 react to produce carbon dioxide.

[0026] The membrane tank system 200 is used to clamp and fix the gas to be tested and to provide a controlled test environment for the gas permeation process, including the membrane tank 210 and the gas permeation membrane 220; The membrane tank 210 is divided into an upper chamber and a lower chamber. A gas permeation membrane 220 is sandwiched between the upper and lower chambers, forming an independent upstream side chamber 211 and a downstream side chamber 212. Carbon dioxide gas permeates through the gas permeation membrane 220 into the downstream side chamber 212. The upstream side chamber 211 is provided with an upstream liquid inlet / outlet, and the downstream side chamber 212 is provided with a downstream liquid inlet / outlet. The upstream liquid inlet is connected to the outlet of the main pipeline. The upstream liquid outlet is used to discharge the reacted solution. Both the downstream liquid inlet and the downstream liquid outlet are connected to the circulation system 300.

[0027] Specifically, the membrane pool 210 is made of aluminum alloy and has threaded holes on its edges. After screws are screwed in, the gas permeation membrane 220 is clamped.

[0028] Specifically, the upstream liquid inlet and the upstream liquid outlet are located at opposite ends of the upstream chamber 211, respectively, for introducing a carbon dioxide mixed solution of a certain concentration. The downstream liquid outlet is located in the downstream chamber 212, for exporting the gas mixed solution that has permeated to the downstream side to the detection and analysis unit; the downstream liquid inlet is used to clean or empty the downstream chamber 212 before testing.

[0029] The gas permeation membrane 220 includes various polymer material membranes. When the polymer material membrane does not have the function of isolating water and / or ions, a gas-permeable and hydrophobic protective layer that only allows carbon dioxide gas to pass through but blocks liquid and ions from passing through is added on the upstream side of the polymer material membrane. The material of the gas-permeable and hydrophobic protective layer is polydimethylsiloxane.

[0030] The membrane tank system 200 also includes a temperature detection unit 230, which is located in the downstream chamber 212. Temperature changes affect conductivity measurements, and the temperature detection unit 230 is used to accurately detect the liquid temperature in the downstream chamber 212 in real time and provide temperature compensation. The inner surfaces of both the upstream chamber 211 and the downstream chamber 212 are provided with spiral flow channels to evenly distribute the flowing liquid. Specifically, both the upstream chamber 211 and the downstream chamber 212 have spiral flow channels with a depth of 0.5 mm on their inward-facing sides.

[0031] The measurement and circulation system 300 integrates detection, fluid transport and self-cleaning functions, including a conductivity sensor 310, a two-way valve 320, a magnetic pump 330, a flow choke 340, a water container 350 and an ion exchange resin tank 360. After being connected to the magnetic pump 330 and the ion exchange resin tank 360 in sequence, the water container 350 returns to the water container 350 through the flow restrictor 340 to form the first liquid circulation pipeline. The magnetic pump 330 is used to provide liquid circulation power, and the flow restrictor 340 is used to stabilize the liquid flow rate and ensure unidirectional liquid flow. The water container 350 and the ion exchange resin tank 360 are connected to provide and purify deionized water for cleaning. The two-way valve 320 is connected to the downstream liquid outlet of the downstream side chamber 212 and is used to control the flow or stagnation of the liquid flowing out of the downstream side chamber 212. The output port of the ion exchange resin tank 360 is connected to the downstream liquid input port of the downstream side chamber 212. The downstream liquid output port of the downstream side chamber 212 is connected to the input port of the water container 350 through the two-way valve 320. When the two-way valve 320 is open, the water container 350 is connected to the magnetic pump 330, the ion exchange resin tank 360, and the downstream side chamber 212 in sequence, and then returns to the water container 350 through the two-way valve 320 to form a second liquid circulation pipeline. The first liquid circulation pipeline and the second liquid circulation pipeline are both connected. The flow restrictor 340 achieves the function of pressure relief and controls the flow rate of the second liquid circulation pipeline. When the two-way valve 320 is closed, the first liquid circulation pipeline is connected and the second liquid circulation pipeline is blocked. A conductivity sensor 310 is also installed on the pipeline between the downstream side chamber 212 and the two-way valve 320 in the second liquid circulation pipeline. The conductivity sensor 310 is used to monitor the conductivity value of the liquid flowing out of the downstream side chamber 212 in real time and continuously.

[0032] Specifically, the two-way valve 320 is used to control the opening and closing of a specific pipeline, assisting in the switching of working modes.

[0033] The magnetic pump 330 provides stable power for fluid circulation.

[0034] The flow damper 340 is installed in the circulation line to stabilize the liquid flow rate.

[0035] Water container 350 is used to store deionized water.

[0036] The ion exchange resin tank 360 is connected downstream of the water container 350 and upstream of the membrane tank to purify liquids and ensure that the deionized water has an extremely low background conductivity.

[0037] The liquid stored in the standard solution bottle 110 is a sodium carbonate solution, and the liquid stored in the acid storage tank 130 is a phosphoric acid solution. The sodium carbonate solution and the phosphoric acid solution react in the main pipeline and the upstream chamber 211 to generate carbon dioxide gas. The carbon dioxide gas permeates from the upstream chamber 211 to the downstream chamber 212 after passing through the gas permeation membrane 220. The solution discharged from the upstream liquid outlet is a mixed solution of sodium carbonate solution and phosphoric acid solution after chemical reaction.

[0038] Specifically, the standard solution bottle 110 is a 500mL glass volumetric flask with a sodium carbonate solution concentration of 1ppmC; the acid storage tank 130 is a 300mL polyethylene bottle with a phosphoric acid solution of 45%; the first syringe pump 120 has a flow rate of 0.5mL / min; and the second syringe pump 140 has an injection flow rate of 0.2μL / min.

[0039] The acid injection pump 140 is equipped with a 500uL microsyringe 141, which draws acid at a flow rate of 1mL / min and injects it into the main pipeline at a flow rate of 0.2uL / min to mix with the standard solution.

[0040] The three-way valve 150 is normally closed. When the three-way valve 150 is open, the acid injection pump 140 is connected to the acid storage tank 130, and the acid injection pump 140 is in the extraction state. When the three-way valve 150 is closed, the acid injection pump 140 is connected to the main pipeline, and the acid injection pump 140 is in the injection state.

[0041] The deionized water stored in water container 350 is purified by ion exchange resin 360 to obtain ultrapure water rinsing membrane tank 210 downstream side chamber 212, so that the conductivity of the liquid inside the downstream side chamber 212 reaches the low level of ultrapure water. Carbon dioxide gas permeates from upstream side chamber 211 to downstream side chamber 212 after passing through gas permeation membrane 220 and dissolves into ultrapure water. The conductivity of ultrapure water in downstream side chamber 212 reaches a high level as the carbon dioxide gas content increases. By detecting the change in conductivity, the change in the content of carbon dioxide gas permeating into downstream side chamber 212 can be obtained.

[0042] The device also includes a control and data processing unit, which is electrically connected to the first injection pump 120, the second injection pump 140, the three-way valve 150, the two-way valve 320, the magnetic pump 330, the temperature detection unit 230, and the conductivity sensor 310, and is used to automatically control the test process and collect and process data.

[0043] A test method for a testing device for carbon dioxide permeability of a permeable membrane. The testing method is as follows: The core of this method is to indirectly and accurately measure the amount of carbon dioxide permeating the membrane using the conductivity method.

[0044] The ultrapure water rinsing membrane tank system 200 provided by the measurement and circulation system 300 ensures that the conductivity of the liquid inside the membrane tank system 200 is at a low level. Various test liquids are provided to the membrane tank system 200 through the sample introduction system 100. The various test liquids react to generate carbon dioxide gas. After passing through the gas permeation membrane 220, the carbon dioxide gas permeates from the upstream side chamber 211 to the downstream side chamber 212 and dissolves into the ultrapure water, thereby increasing the conductivity of the ultrapure water. By detecting the change in conductivity, the change in the content of carbon dioxide gas permeating into the downstream side chamber 212 can be obtained.

[0045] The specific testing method is as follows: Step 1: Open the two-way valve 320 to connect the second liquid circulation pipeline. Start the magnetic pump 330 to pump the deionized water stored in the water container 350 into the ion exchange resin 360 for purification to obtain ultrapure water. Then, the ultrapure water flows into the downstream side chamber 212 of the membrane tank 210 through the second liquid circulation pipeline. Specifically, the entire liquid pipeline is flushed with the deionized water purified by the ion exchange resin tank 360 until the conductivity reading of the ultrapure water flowing out of the downstream side chamber 212 measured by the conductivity sensor 310 stabilizes to the lowest value. Step 2: Switch the three-way valve 150 to connect the second injection pump 140 and the acid storage tank 130, and start the second injection pump 140 to extract the phosphoric acid solution from the acid storage tank 130; after extraction is completed, switch the three-way valve 150 to connect the acid injection pump 140 to the main pipeline, and pump the extracted phosphoric acid solution into the main pipeline. Step 3: Start the first injection pump 120 to pump the sodium carbonate solution in the standard solution bottle 110 into the main pipeline, so that the sodium carbonate solution and phosphoric acid solution are mixed in the main pipeline and then introduced into the upstream chamber 211 of the membrane tank 210 and react to generate carbon dioxide gas. Step 4: Close the two-way valve 320, shutting off the second liquid circulation pipeline, causing the ultrapure water in the downstream chamber 212 to stagnate. The carbon dioxide gas generated in Step 3 escapes from the upstream chamber 211 and permeates through the gas permeation membrane 220 to the downstream chamber 212. Record the change in the conductivity sensor reading over time as follows: Figure 2As shown; based on the conductivity change data, and the quantitative relationship between conductivity change and carbon dioxide permeation, the permeation flux and permeability of carbon dioxide are calculated. Specifically, the permeation flux is calculated by the slope of the conductivity-time curve, and the total amount of carbon dioxide gas generated is obtained based on the amounts of sodium carbonate solution and phosphoric acid solution provided. Thus, the ratio of the permeation flux to the total amount is the permeability. Step 5: Repeat Step 1 to clean the system in preparation for the next test.

[0046] By controlling the opening and closing of the two-way valve 320, the downstream liquid can switch between three states: "rinsing-stillness-measurement," thereby achieving intermittent conductivity detection and system self-cleaning.

[0047] The foregoing has provided a detailed description of the testing device and method for the pore size of hollow fiber membranes provided by this invention. Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the embodiments above are merely for the purpose of helping to understand the method and core ideas of this invention. It should be noted that those skilled in the art can make various improvements and modifications to this invention without departing from its principles, and these improvements and modifications also fall within the protection scope of the claims of this invention.

Claims

1. A device for testing the carbon dioxide permeability of a permeable membrane, characterized in that: It includes a sample introduction system (100), a membrane pool system (200), and a measurement and circulation system (300). The sample introduction system (100) and the membrane pool system (200) are connected by a main pipeline to provide the liquid reagents required for the test and to generate the carbon dioxide gas to be tested. The measurement and circulation system (300) and the membrane pool system (200) are connected by a pipeline to measure the carbon dioxide gas and to clean the membrane pool system (200).

2. The apparatus for testing the carbon dioxide permeability of a permeable membrane according to claim 1, characterized in that: The injection system (100) includes a standard solution bottle (110), a first injection pump (120), an acid storage tank (130), a second injection pump (140), and a three-way valve (150); the main pipeline has two inlets and one outlet, the two inlets being a first inlet and a second inlet; The standard solution bottle (110) is connected to the first inlet of the main pipeline via the first injection pump (120) for pumping the liquid in the standard solution bottle (110) into the main pipeline through the first inlet; the second injection pump (140) is selectively connected to the acid storage tank (130) or the second inlet of the main pipeline via the three-way valve (150) for drawing liquid from the acid storage tank (130) or injecting liquid into the main pipeline; the outlet of the main pipeline is connected to the membrane tank system (200); The liquid in the standard solution bottle (110) and the liquid in the acid storage tank (130) come into contact and react chemically to produce carbon dioxide.

3. The apparatus for testing the carbon dioxide permeability of a permeable membrane according to claim 2, characterized in that: The membrane tank system (200) includes a membrane tank (210) and a gas permeation membrane (220). The membrane tank (210) is divided into an upper chamber and a lower chamber. The gas permeation membrane (220) is sandwiched between the upper chamber and the lower chamber, forming an independent upstream side chamber (211) and a downstream side chamber (212). Carbon dioxide gas permeates from the upstream side chamber (211) through the gas permeation membrane (220) to the downstream side chamber (212). The upstream side chamber (211) is provided with an upstream liquid inlet / outlet, and the downstream side chamber (212) is provided with a downstream liquid inlet / outlet. The upstream liquid inlet is connected to the outlet of the main pipeline. The upstream liquid outlet is used to discharge the reacted solution. The downstream liquid inlet and the downstream liquid outlet are both connected to the circulation system (300).

4. The apparatus for testing the carbon dioxide permeability of a permeable membrane according to claim 3, characterized in that: The gas permeation membrane (220) includes various polymer material membranes. When the polymer material membrane does not have the function of isolating water and / or ions, a breathable and hydrophobic protective layer that only allows carbon dioxide gas to pass through but blocks liquid and ions from passing through is added on the upstream side of the polymer material membrane. The material of the breathable and hydrophobic protective layer is polydimethylsiloxane.

5. The apparatus for testing the carbon dioxide permeability of a permeable membrane according to claim 4, characterized in that: The membrane pool system (200) also includes a temperature detection unit (230), which is located in the downstream side chamber (212) and is used to detect the liquid temperature in the downstream side chamber (212) and provide temperature compensation; the inner surfaces of the upstream side chamber (211) and the downstream side chamber (212) are provided with spiral flow channels.

6. The apparatus for testing the carbon dioxide permeability of a permeable membrane according to claim 5, characterized in that: The measurement and circulation system (300) includes a conductivity sensor (310), a two-way valve (320), a magnetic pump (330), a flow choke (340), a water container (350), and an ion exchange resin tank (360). The water container (350) is connected in sequence to the magnetic pump (330) and the ion exchange resin tank (360), and then returns to the water container (350) through the flow restrictor (340) to form the first liquid circulation pipeline; The two-way valve (320) is connected to the downstream liquid outlet of the downstream side chamber (212) to control the flow or stillness of the liquid flowing out of the downstream side chamber (212); The outlet of the ion exchange resin tank (360) is connected to the downstream liquid inlet of the downstream side chamber (212). The downstream liquid outlet of the downstream side chamber (212) is connected to the inlet of the water container (350) through a two-way valve (320). When the two-way valve (320) is open, the water container (350) is connected to the magnetic pump (330), the ion exchange resin tank (360), and the downstream side chamber (212) in sequence, and then returns to the water container (350) through the two-way valve (320) to form a second liquid circulation pipeline. The first liquid circulation pipeline and the second liquid circulation pipeline are both connected. When the two-way valve (320) is closed, the first liquid circulation pipeline is connected, and the second liquid circulation pipeline is not connected. The conductivity sensor (310) is also installed on the pipeline between the downstream side chamber (212) and the two-way valve (320) in the second liquid circulation pipeline. The conductivity sensor (310) is used to monitor the conductivity of the liquid in the downstream side chamber (212).

7. The apparatus for testing the carbon dioxide permeability of a permeable membrane according to claim 6, characterized in that: The liquid in the standard solution bottle (110) is a sodium carbonate solution, and the liquid in the acid storage tank (130) is a phosphoric acid solution. The sodium carbonate solution and the phosphoric acid solution react in contact in the main pipeline and the upstream side chamber (211) to generate carbon dioxide gas. The carbon dioxide gas permeates from the upstream side chamber (211) to the downstream side chamber (212) after passing through the gas permeation membrane (220). The solution discharged from the upstream liquid outlet is a mixed solution of sodium carbonate solution and phosphoric acid solution after chemical reaction.

8. The apparatus for testing the carbon dioxide permeability of a permeable membrane according to claim 7, characterized in that: The deionized water stored in the water container (350) is purified by the ion exchange resin (360) to obtain the downstream side chamber (212) of the ultrapure water rinsing membrane tank (210), so that the conductivity of the liquid inside the downstream side chamber (212) reaches the low level of ultrapure water. The carbon dioxide gas permeates from the upstream side chamber (211) to the downstream side chamber (212) after passing through the gas permeation membrane (220) and dissolves into the ultrapure water. The conductivity of the ultrapure water liquid inside the downstream side chamber (212) reaches a high level as the carbon dioxide gas content increases. The change in the carbon dioxide gas content that has permeated into the downstream side chamber (212) can be obtained by detecting the change in conductivity.

9. A test method using the carbon dioxide permeability testing apparatus for a permeable membrane as described in claim 8, characterized in that, The testing method is as follows: The ultrapure water provided by the measurement and circulation system (300) flushes the membrane tank system (200) to reduce the conductivity of the liquid inside the membrane tank system (200) to a low level. The sample introduction system (100) provides various test liquids to the membrane tank system (200). The various test liquids react to generate carbon dioxide gas. The carbon dioxide gas permeates from the upstream side chamber (211) to the downstream side chamber (212) after passing through the gas permeation membrane (220), and then dissolves into the ultrapure water, thereby increasing the conductivity of the ultrapure water. The change in the content of carbon dioxide gas permeating into the downstream side chamber (212) can be obtained by detecting the change in conductivity.

10. The test method for a carbon dioxide permeability testing device for a permeable membrane according to claim 9, characterized in that, The specific testing method is as follows: Step 1: Open the two-way valve (320), connect the second liquid circulation pipeline, start the magnetic pump (330), pump the deionized water stored in the water container (350) into the ion exchange resin (360) for purification to obtain ultrapure water, and then the ultrapure water flows into the downstream side chamber (212) of the membrane tank (210) through the second liquid circulation pipeline until the conductivity sensor (310) measures the conductivity reading of the ultrapure water flowing out of the downstream side chamber (212) and stabilizes to the lowest value; Step 2: Switch the three-way valve (150) to connect the second injection pump (140) and the acid storage tank (130), start the second injection pump (140) to extract the phosphoric acid solution from the acid storage tank (130); after extraction is completed, switch the three-way valve (150) to connect the acid injection pump (140) to the main pipeline, and pump the extracted phosphoric acid solution into the main pipeline; Step 3: Start the first injection pump (120) to pump the sodium carbonate solution in the standard solution bottle (110) into the main pipeline, so that the sodium carbonate solution and phosphoric acid solution are mixed in the main pipeline and then introduced into the upstream side chamber (211) of the membrane tank (210) and react to generate carbon dioxide gas. Step 4: Close the two-way valve (320), shut off the second liquid circulation pipeline, and allow the ultrapure water in the downstream chamber (212) to stand still. The carbon dioxide gas generated in Step 3 permeates from the upstream chamber (211) through the gas permeation membrane (220) to the downstream chamber (212). Record the reading change of the conductivity sensor (310). Based on the conductivity change data, and the quantitative relationship between conductivity change and carbon dioxide permeation, calculate the carbon dioxide permeation flux and permeability. Step 5: Repeat step 1 to prepare for the next test.

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