Simple and efficient polar molecule adsorption measurement device and method thereof

Abstract

The invention discloses a simple and efficient polar molecule adsorption measurement device which comprises a gas supply unit, a switch needle valve, a vacuum gauge, a vacuum tank, a heating system, a vacuum pump, a high-precision balance and a data acquisition and processing unit, one end of the switch needle valve is connected to the gas supply unit through a valve gas pipe, the other end of the switch needle valve is connected with the vacuum tank, the vacuum gauge and the vacuum pump are connected with the vacuum tank through pipelines, and the high-precision balance located in the vacuum tank is connected with the data acquisition and processing unit through an adapter flange; the gas supply unit is used for providing polar water molecules and other mixed gases; the heating system is used for heating the vacuum tank; the high-precision balance is used for measuring the adsorption weight of polar molecules; the data collecting and processing unit is used for collecting and processing data in the experiment process. The invention further discloses a simple and efficient polar molecule adsorption measurement method. According to the invention, the device cost can be reduced on the basis of ensuring the experiment precision and reliability.

Description

Technical Field

[0001] The invention relates to the technical field of gas adsorption amount determination, and in particular to a simple and efficient polar molecule adsorption measurement device and method thereof. Background Art

[0002] The lunar soil water molecule analyzer on board has achieved a highly accurate inversion of the water ice content in the lunar soil by drilling, heating and extracting the lunar soil. However, due to the adsorption of polar water molecules on the surface of the metal pipe, the amount of water vapor entering the analyzer will be reduced, which will lead to an increase in the error of the water ice content inversion result. Therefore, in order to improve the accuracy of the water ice content inversion, it is necessary to carry out a calibration experiment on the adsorption of polar water molecules on the surface of the metal pipe to ensure the accuracy of the measurement results.

[0003] At present, the volumetric method and the gravimetric method are mainly used to determine the amount of gas adsorption. As an indirect measurement technology, the volumetric method is based on the law of conservation of mass. The adsorption amount is determined by calculating the difference in the amount of gas in the free space before and after adsorption. The accuracy of this method is affected by many factors, including the choice of the gas state equation, the accurate calibration of the free space volume, and the measurement accuracy of the pressure and temperature sensors. The gravimetric method is a direct measurement technology that calculates the adsorption amount based on the weight change of the sample before and after adsorption. The accuracy of this method depends on the accuracy of the balance, and the test error is easy to control.

[0004] However, the above methods are currently complicated to operate and have large equipment volumes. At the same time, polar water molecules are different from other non-polar molecules (helium and nitrogen, etc.), and their adsorption effect in metal materials is obvious, especially in vacuum systems. The use of traditional measurement methods will result in large measurement deviations.

[0005] Therefore, there is an urgent need to provide a new, simple and efficient polar molecule adsorption measurement device and method to solve the above problems. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a simple and efficient polar molecule adsorption measurement device and method thereof, which can reduce the device cost on the basis of ensuring the experimental accuracy and reliability.

[0007] In order to solve the above technical problems, a technical solution adopted by the present invention is: to provide a simple and efficient polar molecule adsorption measurement device, including a gas supply unit, a switch needle valve, a vacuum gauge, a vacuum tank, a heating system, a vacuum pump, a high-precision balance, and a data acquisition and processing unit;

[0008] One end of the switch needle valve is connected to the air supply unit through a valve air pipe, and the other end is connected to the vacuum tank. The vacuum gauge and the vacuum pump are connected to the vacuum tank through pipelines. The high-precision balance in the vacuum tank is connected to the data acquisition and processing unit through an adapter flange.

[0009] The gas supply unit is used to provide polar water molecules and other mixed gases; the heating system is used to heat the vacuum tank; the high-precision balance is used to measure the adsorption weight of polar molecules; and the data acquisition and processing unit is used to collect and process data during the experiment.

[0010] In a preferred embodiment of the present invention, a temperature sensor is connected to the outside of the vacuum tank to monitor the temperature inside the vacuum tank.

[0011] In a preferred embodiment of the present invention, the main body of the heating system is a heating belt made of glass fiber material, which is used to heat the vacuum tank.

[0012] In a preferred embodiment of the present invention, the vacuum pump is used to evacuate the vacuum tank, and a solenoid valve is provided between the vacuum pump and the vacuum tank for controlling the opening and closing.

[0013] In a preferred embodiment of the present invention, the high-precision balance includes an electrode sheet, a retaining ring for protecting the electrode sheet, a transfer flange port, and a data interface;

[0014] The electrode sheet is used to measure the adsorption weight of polar molecules and serves as a weighing end;

[0015] The adapter flange is installed on the tank wall of the vacuum tank, one end of the adapter flange port is connected to the weighing end through a crystal bracket, and the other end of the adapter flange port is connected to the data interface through a crystal bracket;

[0016] The data interface is used to connect to the data acquisition and processing unit.

[0017] Furthermore, the electrode sheets are quartz crystal electrode sheets made of different metal materials and with different roughness.

[0018] In a preferred embodiment of the present invention, the data acquisition and processing unit acquires the temperature and pressure of the vacuum tank, and processes and calculates the adsorption amount of polar molecules.

[0019] In order to solve the above technical problems, another technical solution adopted by the present invention is: to provide a polar molecule adsorption measurement method using a simple and efficient polar molecule adsorption measurement device as described in any one of the above items, comprising the following steps:

[0020] S1: Check the airtightness of the measuring device by reading the changes in the vacuum gauge. When the vacuum leakage rate of the system is less than 10 -4 Pa·m3 / s, heating the vacuum tank by the heating system, and starting the test after the air tightness of the device is tested to be good and the temperature of the vacuum tank is kept balanced;

[0021] S2: The gas supply unit provides a single gas or mixed gases in different proportions, the initial pressure is fixed at P0, and the switch needle valve is closed;

[0022] S3: Turn on the vacuum pump and pump air for several minutes to evacuate the air in the vacuum tank and observe the changes in the vacuum gauge. When the pressure is lower than 1Pa, introduce the mixed gas into the vacuum tank;

[0023] S4: Turn on the high-precision balance, let it stand for several minutes, and adjust the balance to zero;

[0024] S5: By adjusting the needle valve, set different pressure points under the experimental pressure. When the set pressure is reached, close the switch needle valve, and record the pressures P1, P2 and the high-precision balance readings m1, m2 after standing for several minutes; m1, m2 represent the adsorption mass of the high-precision balance, and the adsorption amount per unit area m'1 and m'2 is obtained through the fixed area of ​​the high-precision balance;

[0025] S6: After several measurements, the adsorption amount is calculated according to the following formula. When P0 is the same, the adsorption amount per unit area m'1 and m'2 is used to calculate the total adsorption amount of the entire device. The average value of several calculated values ​​is taken as the final total adsorption amount:

[0026] According to the ideal gas state equation PV=nRT, we can get Where P is pressure, the unit is Pa; V is volume, the unit is m 3 ; R is a fixed value, equal to 8.31 J / (mol*K); T is the temperature, the unit is K; m is the mass of the gas, n is the amount of substance, and M is the molar mass of the gas;

[0027]

[0028] Subtracting formula (1) from (2), we get

[0029] Among them, S0 is the area of ​​the high-precision balance electrode, and S1 is the area inside the entire pipeline.

[0030] In a preferred embodiment of the present invention, in step S5, the pressure adjustment range is 10Pa to 1100Pa, and the pressure adjustment error of each switching needle valve is controlled within 1%.

[0031] In a preferred embodiment of the present invention, the adsorption amount of polar molecules at different temperatures can be tested by adjusting the temperature of the vacuum tank.

[0032] The beneficial effects of the present invention are as follows: the simple and efficient polar molecule adsorption measurement device provided by the present invention does not involve the problem of selecting the gas state equation compared to the volumetric adsorption device, and its test accuracy only depends on the accuracy of the balance, and the test error is easier to control; by modifying the high-precision balance, the device cost is reduced on the basis of ensuring the experimental accuracy and reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a structural block diagram of a preferred embodiment of a simple and efficient polar molecule adsorption measurement device of the present invention;

[0034] Figure 2 is a structural schematic diagram of the high-precision balance;

[0035] Figure 3 This is a data graph of gas adsorption measured by the measuring device at different experimental pressures;

[0036] Figure 4 The present invention is a flowchart of a simple and efficient polar molecule adsorption measurement method.

[0037] The components in the accompanying drawings are marked as follows: 1. Air supply unit, 2. Switch needle valve, 3. Vacuum gauge, 4. Vacuum tank, 5. Temperature sensor, 6. Heating system, 7. High-precision balance, 71. Guard ring, 72. Electrode sheet, 73. Adapter flange port, 74. Crystal bracket, 75. Data interface, 8. Solenoid valve, 9. Vacuum pump, 10. Adapter flange, 11. Data acquisition and processing unit. DETAILED DESCRIPTION

[0038] The preferred embodiments of the present invention are described in detail below in conjunction with the accompanying drawings so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making a clearer and more definite definition of the protection scope of the present invention.

[0039] See also Figure 1 , the embodiment of the present invention includes:

[0040] A simple and efficient polar molecule adsorption measurement device comprises a gas supply unit 1, a switch needle valve 2, a vacuum gauge 3, a vacuum tank 4, a heating system 6, a vacuum pump 9, a high-precision balance 7, and a data acquisition and processing unit 11. One end of the switch needle valve 2 is connected to the gas supply unit 1 through a valve air pipe, and the other end is connected to the vacuum tank 4, and the gas enters the vacuum tank 4 through the switch needle valve 2. The vacuum gauge 3 and the vacuum pump 9 are both connected to the vacuum tank 4 through pipelines, and the high-precision balance 7 located in the vacuum tank 4 is connected to the data acquisition and processing unit 11 through an adapter flange.

[0041] In this example, the gas supply unit 1 is a sample tank for providing polar water molecules and other mixed gases. The main body of the heating system 6 is a heating belt made of glass fiber material, which is used to heat the vacuum tank 4. The high-precision balance 7 stored in the vacuum tank 4 is used to test the adsorption weight of polar molecules with an accuracy of up to ng. The vacuum gauge 3 is used to measure the pressure in the vacuum tank 4 and the pipeline, and the measurement accuracy is not less than 3%. The vacuum pump 9 is used to extract the gas in the sample vacuum tank 4, and a solenoid valve 8 is set between the vacuum pump 9 and the vacuum tank 4 for controlling the opening and closing. The vacuum tank 4 is externally connected to a temperature sensor 5 for monitoring the temperature in the vacuum tank 4. The data acquisition and processing unit 11 is used to collect and process data during the experiment.

[0042] The high-precision balance 7 includes an electrode sheet 72, a retaining ring 71 for protecting the electrode sheet 72, an adapter flange port 73, and a data interface 75. The electrode sheet 72 is used to measure the adsorption weight of polar molecules as a weighing end. The adapter flange 10 is installed on the tank wall of the vacuum tank 4, and the adapter flange port 73 at one end is connected to the weighing end through a crystal bracket 74, and the adapter flange port 73 at the other end is connected to the data interface 75 through a crystal bracket 74. The data interface 75 is used to connect the data acquisition and processing unit 11. The adapter flange 10 is used for connection, one end is fixed to the weighing end, and the other end realizes the precise docking of the data transmission interface. This modification measure not only effectively improves the stability and accuracy of weighing and data transmission, but also ensures that the vacuum tank 4 maintains its good vacuum during operation.

[0043] Furthermore, the electrode sheet 72 is a quartz crystal electrode sheet made of different metal materials. In this example, the electrode sheet 72 is a smooth aluminum metal quartz crystal electrode sheet.

[0044] The high-precision balance 7 is a highly sensitive mass detection instrument. Its working principle is based on the relationship between the frequency of a quartz crystal oscillator and the mass loaded on the crystal. When a quartz crystal is subjected to mechanical stress, a piezoelectric effect will occur on its surface. The quartz crystal will resonate at a specific frequency, at which the amplitude is the largest. This frequency is called the natural frequency. When additional mass (such as a molecular layer, a thin film, etc.) is attached to the surface of the crystal, the resonant frequency of the crystal will decrease. Based on the Sauerbrey equation, the relationship between the change in crystal mass and the change in its resonant frequency is described as follows:

[0045]

[0046] Where Δf is the change in the crystal resonant frequency, in Hz; f is the original resonant frequency of the quartz crystal, in Hz; Δm is the mass change, in g; A is the effective area of ​​the crystal electrode, in g; p q is the density of the crystal. The density of quartz is about 2.65g / cm 3;u q The shear modulus of quartz crystal is about 2.947×10^11dyn / cm for quartz. 2 .

[0047] According to the above formula, when a substance is adsorbed on the surface of the crystal, the total mass of the crystal changes, causing a slight change in its resonant frequency. By accurately measuring the frequency change of the electrode sheet, the balance can achieve high-precision detection of trace substances.

[0048] The data acquisition and processing unit 11 acquires the temperature and pressure of the vacuum tank 4 and processes and calculates the adsorption amount of polar molecules.

[0049] Compared with the volumetric adsorption device, the simple and efficient polar molecule adsorption measurement device described in the present invention does not involve the problem of selecting the gas state equation. Its test accuracy only depends on the accuracy of the balance, and the test error is easier to control. By modifying the high-precision balance, the cost of the device is reduced while ensuring the experimental accuracy and reliability.

[0050] See also Figure 4 , a simple and efficient polar molecule adsorption measurement method is provided in the example of the present invention, comprising the following steps:

[0051] S1: Check the airtightness of the measuring device by reading the changes in the vacuum gauge. When the vacuum leakage rate of the system is less than 10 -4 Pa·m 3 / s, the vacuum tank is heated by the heating system, in this example, it is heated to 35°C, and the test is started after the air tightness test of the device is good and the temperature of the vacuum tank is kept balanced;

[0052] S2: The gas supply unit provides a single gas or mixed gases of different proportions, the initial pressure is fixed at P0, the pressure error of each gas injection is controlled within 1%, and the switch needle valve is closed;

[0053] S3: Turn on the vacuum pump and evacuate the air in the vacuum tank for 30 minutes. Observe the changes in the vacuum gauge. When the pressure is lower than 1Pa, introduce the mixed gas into the vacuum tank.

[0054] S4: Turn on the high-precision balance, let it stand for 15 minutes, and adjust the balance to zero;

[0055] S5: By adjusting the needle valve, set different pressure points under the experimental pressure. When the set pressure is reached, close the switch needle valve, and record the pressures P1, P2 and the high-precision balance readings m1, m2 after standing for 15 minutes; m1, m2 represent the adsorption mass of the high-precision balance, the pressure adjustment range is 10Pa to 1100Pa, and the pressure adjustment error of each switch needle valve is controlled within 1%;

[0056] S6: After several measurements, the adsorption amount is calculated according to the following formula, and the average value of the calculated values ​​is taken to finally give the gas adsorption amount under different pressures, such as Figure 3 shown.

[0057] When P0 is the same, the total adsorption amount of the entire device can be calculated by the adsorption amount per unit area m'1 and m'2. The calculation method is as follows:

[0058] According to the ideal gas state equation PV=nRT, we can get Where P is pressure, the unit is Pa; V is volume, the unit is m 3 ; R is a fixed value, equal to 8.31 J / (mol*K); T is the temperature, the unit is K; m is the mass of the gas, n is the amount of substance, and M is the molar mass of the gas;

[0059]

[0060] Subtracting formula (1) from (2), we get Furthermore, we get

[0061] Among them, S0 is the area of ​​the high-precision balance electrode, and S1 is the area inside the entire pipeline.

[0062] Similarly, by adjusting the temperature of the vacuum tank, the adsorption capacity test at different temperatures can be achieved using the same steps.

[0063] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A simple and efficient polar molecule adsorption measurement device, characterized in that: Including gas supply unit, switch needle valve, vacuum gauge, vacuum tank, heating system, vacuum pump, high-precision balance, data acquisition and processing unit; One end of the switch needle valve is connected to the air supply unit through a valve air pipe, and the other end is connected to the vacuum tank. The vacuum gauge and the vacuum pump are connected to the vacuum tank through pipelines. The high-precision balance in the vacuum tank is connected to the data acquisition and processing unit through an adapter flange. The gas supply unit is used to provide polar water molecules and other mixed gases; the heating system is used to heat the vacuum tank; the high-precision balance is used to measure the adsorption weight of polar molecules; and the data acquisition and processing unit is used to collect and process data during the experiment.

2. The simple and efficient polar molecule adsorption measurement device according to claim 1 is characterized in that: The outside of the vacuum tank is connected with a temperature sensor for monitoring the temperature inside the vacuum tank.

3. The simple and efficient polar molecule adsorption measurement device according to claim 1 is characterized in that: The main body of the heating system is a heating belt made of glass fiber material, which is used to heat the vacuum tank.

4. The simple and efficient polar molecule adsorption measurement device according to claim 1 is characterized in that: The vacuum pump is used to evacuate the vacuum tank, and a solenoid valve is arranged between the vacuum pump and the vacuum tank to control opening and closing.

5. The simple and efficient polar molecule adsorption measurement device according to claim 1 is characterized in that: The high-precision balance includes an electrode sheet, a retaining ring for protecting the electrode sheet, a transfer flange port, and a data interface; The electrode sheet is used to measure the adsorption weight of polar molecules and serves as a weighing end; The adapter flange is installed on the tank wall of the vacuum tank, one end of the adapter flange port is connected to the weighing end through a crystal bracket, and the other end of the adapter flange port is connected to the data interface through a crystal bracket; The data interface is used to connect to the data acquisition and processing unit.

6. The simple and efficient polar molecule adsorption measurement device according to claim 5 is characterized in that: The electrode sheets are quartz crystal electrode sheets with different metal materials and different roughness.

7. The simple and efficient polar molecule adsorption measurement device according to claim 1 is characterized in that: The data acquisition and processing unit acquires the temperature and pressure of the vacuum tank, and processes and calculates the adsorption amount of polar molecules.

8. A method for measuring polar molecule adsorption using the simple and efficient polar molecule adsorption measuring device as claimed in any one of claims 1 to 7, characterized in that: The following steps are involved: S1: Check the airtightness of the measuring device by reading the changes in the vacuum gauge. When the vacuum leakage rate of the system is less than 10 -4 Pa·m 3 / s, the vacuum tank is heated by the heating system, and the airtightness of the device is The test starts after the test is good and the temperature of the vacuum tank is balanced; S2: The gas supply unit provides a single gas or mixed gases in different proportions, the initial pressure is fixed at P0, and the switch needle valve is closed; S3: Turn on the vacuum pump and pump air for several minutes to evacuate the air in the vacuum tank and observe the changes in the vacuum gauge. When the pressure is lower than 1Pa, introduce the mixed gas into the vacuum tank; S4: Turn on the high-precision balance, let it stand for several minutes, and adjust the balance to zero; S5: By adjusting the needle valve, set different pressure points under the experimental pressure. When the set pressure is reached, close the switch needle valve, and record the pressures P1, P2 and the high-precision balance readings m1, m2 after standing for several minutes; m1, m2 represent the adsorption mass of the high-precision balance, and the adsorption amount per unit area m'1 and m'2 is obtained through the fixed area of ​​the high-precision balance; S6: After several measurements, the adsorption amount is calculated according to the following formula. When P0 is the same, the adsorption amount per unit area m'1 and m'2 is used to calculate the total adsorption amount of the entire device. The average value of several calculated values ​​is taken as the final total adsorption amount: According to the ideal gas state equation PV=nRT, we can get Where P is pressure in Pa; V is volume in m3; R is a fixed value equal to 8.31 J / (mol*K); T is temperature in K; m is gas mass, n is the amount of substance, and M is gas molar mass; Subtracting formula (1) from (2), we get Among them, S0 is the area of ​​the high-precision balance electrode, and S1 is the area inside the entire pipeline.

9. The simple and efficient polar molecule adsorption measurement method according to claim 8, characterized in that: In step S5, the pressure adjustment range is 10Pa to 1100Pa, and the pressure adjustment error of each switch needle valve is controlled within 1%.

10. The simple and efficient polar molecule adsorption measurement method according to claim 8, characterized in that: By adjusting the temperature of the vacuum tank, the adsorption amount of polar molecules at different temperatures can be tested.

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