Accurate Determination Method for Total Hydrogen Content in Water Body Containing Ultra-Fine Hydrogen Bubbles

Abstract

The present invention discloses an accurate determination method for the total hydrogen content in a water body containing ultrafine hydrogen bubbles. This method comprises the following steps: Step 1, sealing a water sample containing ultrafine hydrogen bubbles to be measured in an anaerobic bottle; Step 2, using the freeze-thaw technique to release the hydrogen in the ultrafine bubbles in the water sample into the headspace of the anaerobic bottle; Step 3, using a gas chromatograph to measure the percentage of hydrogen in the headspace of the anaerobic bottle; Step 4, accurately measuring the volume of the water sample in the anaerobic bottle, the headspace volume, the air pressure inside the bottle, and the measurement temperature, and calculating the total hydrogen content in the water sample through a formula. The method proposed by the present invention has no requirements for the dissolved hydrogen concentration of the sample and the presence or absence of redox substances in the water sample, and has the advantages of high sensitivity, accuracy, convenience for popularization and application, etc.

Description

Technical Field

[0001] The invention relates to the technical field of hydrogen concentration determination in a dispersed phase of hydrogen-containing water bubbles, in particular to a method for accurately determining the total hydrogen content in a water body containing ultrafine hydrogen bubbles. Background Art

[0002] Hydrogen molecules are recognized as ideal biological antioxidants due to their unique properties such as selective antioxidant, strong diffusivity and biosafety. They are used to alleviate oxidative damage caused by external stress and free radicals to organisms. To date, hydrogen molecules have been shown to have therapeutic effects on a variety of human diseases and animal models related to oxidative stress, and can effectively regulate plant growth and development and improve plant tolerance to external stress. They are widely used in medicine, botany, agronomy and other fields. However, there are difficulties in the application of hydrogen molecules, mainly because their high diffusivity significantly reduces their solubility and residence time in water. Therefore, finding efficient technical methods to quickly dissolve hydrogen in water while extending its residence time as much as possible has become a challenging key issue for the large-scale application of hydrogen molecules in the field of water environment.

[0003] In recent years, the discovery of ultrafine bubble technology and the emergence of related technical methods have opened up a new research path to solve the bottleneck problem of hydrogen molecules in water environment, medicine and agricultural applications. Compared with ordinary soluble hydrogen molecules, hydrogen molecules in the form of ultrafine bubbles have many unique properties and application advantages, which are mainly manifested in the following two aspects: First, ultrafine bubbles have a large specific surface area and negative surface charge, which greatly improves the solubility and storage time of hydrogen in water. Second, the interior of ultrafine bubbles is an extreme environment of high pressure and high density, which leads to the high activity of hydrogen molecules inside ultrafine bubbles and their ability to remove free radicals is stronger.

[0004] Hydrogen concentration is a key indicator in hydrogen applications, so it is particularly important to accurately measure hydrogen concentration. The current methods for measuring hydrogen content in water include oxidation titration using methylene blue platinum colloid reagent and gas chromatography; however, ultrafine bubbles have a great influence on the measurement results of hydrogen content in water, and the existing methods may cause large errors in the results because they do not consider the influence of ultrafine bubbles. Summary of the invention

[0005] The present invention aims at the deficiencies in the prior art and provides a method for accurately determining the total hydrogen content in water containing ultrafine hydrogen bubbles.

[0006] The technical solution of the present invention is as follows:

[0007] A method for accurately determining the total hydrogen content in water containing ultrafine hydrogen bubbles, characterized in that it comprises the following steps:

[0008] Step 1: Seal the water sample to be tested containing ultrafine hydrogen bubbles in an anaerobic bottle.

[0009] Step 2: Use the freeze-thaw technique to release the hydrogen in the ultrafine bubbles in the water sample into the headspace in the anaerobic bottle.

[0010] Step 3: Use a gas chromatograph to measure the hydrogen content in the headspace.

[0011] Step 4: Determine the total hydrogen content in the water sample based on the volume of the water sample in the anaerobic bottle, the volume of the headspace, the air pressure, and the temperature.

[0012] In Step 1, before sealing the water sample, take a certain amount of the water sample and titrate and measure the dissolved hydrogen in the water sample using methylene blue platinum colloid reagent to estimate the dissolved hydrogen content; then seal the water sample to be tested containing ultrafine hydrogen bubbles in an anaerobic bottle through a butyl rubber stopper, an aluminum cap, and a bottle opener, and the volume of the water sample to be tested accounts for ≤ 80% of the volume of the anaerobic bottle.

[0013] The freeze-thaw technique in Step 2 includes the following steps: Step 2a: Place the anaerobic bottle horizontally in a refrigerator at 4°C for 12 hours; Step 2b: Transfer the anaerobic bottle to a refrigerator at -20°C and place it for ≥ 24 hours to ensure that the water sample to be tested undergoes a phase change and becomes solid ice; Step 2c: Thaw the solid ice water sample to be tested at room temperature to make it return to the liquid water sample to be tested.

[0014] In Step 3, a capillary column or a packed column is used to measure the hydrogen content in the headspace; the operating conditions for using a capillary column are as follows: a) Carrier gas: argon or helium, constant flow mode, column outlet measurement flow rate is 12 mL / min; b) Gas injection volume: 0.2 mL; c) Chromatographic column: molecular sieve with model Msieve5A, length 30 m, outer diameter 0.53 mm, inner diameter 50 μm; d) Column temperature: 100°C; e) Thermal conductivity detector TCD temperature 110°C; the operating conditions for using a packed column are as follows: a) Carrier gas: argon or helium, constant flow mode, column outlet measurement flow rate is 30 mL / min; b) Gas injection volume: 1 ml; c) Chromatographic column: molecular sieve with model Msieve5A, length 1.83 m, outer diameter 3.1 mm, inner diameter 2 mm, mesh 60 - 80 mesh; d) Column temperature 60°C.

[0015] The volume V of the water sample in Step 4 water and the volume V of the headspace gas are calculated as follows:

[0016]

[0017]

[0018] Where Ma is the mass of the anaerobic bottle containing the water sample to be measured, Mb is the mass of the empty anaerobic bottle, ρ is the density of ultrapure water, and V total is the total volume of the anaerobic bottle, and M T is the mass of ultrapure water corresponding to when the anaerobic bottle is filled with ultrapure water.

[0019] In step 4, it includes converting the headspace hydrogen content obtained by the gas chromatograph from volume % to mol / m 3 , and the conversion formula is as follows:

[0020]

[0021] Where i is the gas component hydrogen; C i is the hydrogen concentration; C i，％ is the volume percentage concentration of hydrogen; is the molar concentration of hydrogen mol / m 3 ; n is the number of moles of the headspace gas g / mol; n i is the number of moles of hydrogen g / mol; P0 is the standard atmospheric pressure latm; T0 is the standard temperature 273.15K; P is the pressure of the headspace gas atm; V is the volume of the headspace mL; R is the gas constant, R = 8.20544×10 -5 m 3 atm / mol K; T is the temperature of the headspace gas K.

[0022] In step 4, it includes calculating the total hydrogen content in the water sample using the following formula

[0023]

[0024] Where is the molar mass of hydrogen,

[0025] In step 3, it includes establishing a calibration curve for the relationship between the hydrogen concentration and the hydrogen peak area in the gas chromatography. The calibration curve is used for standard hydrogen with known percentages of 1%, 5%, 10%, 20%, 40%, 60%, and 80%. The peak area signal of hydrogen is converted into the hydrogen percentage concentration using the non-linear equation in the standard curve.

[0026] The technical effects of the present invention are as follows: The present invention provides an accurate determination method for the total hydrogen content in a water body containing hydrogen ultrafine bubbles. By using the gas chromatography headspace method, the total hydrogen concentration in water can be accurately measured, and there are no requirements for the dissolved hydrogen concentration of the sample and the presence or absence of redox substances in the water sample. It has the advantages of high sensitivity, accuracy, convenient promotion and application, etc.

[0027] The advantages of the technical method of the present invention are as follows:

[0028] (1) This method has no requirements for the dissolved oxygen of the sample and the presence or absence of redox substances contained therein.

[0029] (2) This method has no requirements for the concentration range of hydrogen content in the sample, and the measurement results are accurate.

[0030] (3) This method can simultaneously measure the dissolved hydrogen molecules in water and the hydrogen molecules existing in the form of ultrafine bubbles. Description of the Drawings

[0031] Figure 1 It is an exploded combination schematic diagram of a water sample sealing device involved in the accurate measurement method for the total hydrogen content in a water body containing ultrafine hydrogen bubbles of the present invention. Figure 1 It includes a butyl rubber stopper A, an aluminum cap B, an empty anaerobic bottle C, a sealed water sample anaerobic bottle D, and a bottle opener E. During the water sample sealing or closing, the water sample is placed in the empty anaerobic bottle C, the butyl rubber stopper A is covered on the bottle mouth, and then the aluminum cap B is sealed on the bottle mouth with the bottle opener E.

[0032] Figure 2 It is an actual change diagram of the water sample color during the titration process involved in the accurate measurement method for the total hydrogen content in a water body containing ultrafine hydrogen bubbles of the present invention. Figure 2 It includes a left figure, a middle figure, and a right figure. The left figure shows the situation of adding methylene blue to the water sample. The middle figure shows that the added blue methylene blue is reduced to colorless by hydrogen molecules. The right figure shows that the solution turns blue at the titration end point. By titrating and measuring the dissolved hydrogen in the water sample, the dissolved hydrogen content in the water sample can be estimated.

[0033] Figure 3 It is a schematic diagram of the extraction of headspace gas involved in the accurate measurement method for the total hydrogen content in a water body containing ultrafine hydrogen bubbles of the present invention. Figure 3 The headspace gas above the water sample G in the sealed water sample anaerobic bottle D is extracted by a sampling needle F.

[0034] Figure 4 It is a schematic flow diagram of the accurate measurement method for the total hydrogen content in a water body containing ultrafine hydrogen bubbles of the present invention. Figure 4It includes sample preservation, bubble elimination, and gas phase analysis. Sample preservation includes sealing the water sample to be tested containing ultra-fine hydrogen bubbles in an anaerobic bottle. The lower half inside the anaerobic bottle is the ultra-fine bubble dispersion phase, and the upper half is air. In bubble elimination, the freeze-thaw technique is used to release the dissolved hydrogen molecules and hydrogen in the form of ultra-fine bubbles in the water sample from the liquid phase to the headspace of the anaerobic bottle, so that the headspace gas in the anaerobic bottle contains air and hydrogen, and the hydrogen is fully released from the water body in the anaerobic bottle, including the following steps: Step 1, horizontally place the anaerobic bottle filled with ultra-fine hydrogen bubble water in a refrigerator at 4°C for 12 hours; Step 2, transfer the anaerobic bottle to a refrigerator at -20°C and place it for more than 24 hours to ensure that the liquid sample undergoes a phase change and becomes solid ice; Step 3, thaw the sample at room temperature to restore it to the liquid state. Gas phase analysis includes injecting the headspace gas extracted by a syringe through an injection port into a detector. The detector is connected to an argon gas cylinder through an MFC (Mass Flow Controller), and the detector has a display, and the display shows a gas chromatogram. The gas phase analysis parameters include flow rate = 12 ml / min, injection volume = 0.2 ml, column temperature = 100°C, and detector temperature = 110°C.

[0035] Figure 5 It is the calibration curve of standard hydrogen involved in the accurate determination method of the total hydrogen content in the water body containing ultra-fine hydrogen bubbles of the present invention. Figure 5 In it, the ordinate is the response intensity (Y-axis, dimensionless), and 6e+06 represents 6×10 6 , in the large coordinate, the abscissa is the retention time (X-axis, min), and in the small coordinate, the abscissa is the standard concentration (X'-axis, volume %). In the large coordinate, the curves from top to bottom are the gas chromatograms of standard hydrogen with different volume concentrations % (100% - 50% - 20% - 10% - 5% - 1% - 0.5%). The X-axis represents the retention time (min), the Y-axis represents the detection response intensity (dimensionless), X' represents the standard concentration (volume %), and the formula is Y = 11.3052X 3 - 3023.59X 2 + 558840X, R2 = 0.9999, and X in the formula represents the standard concentration.

[0036] Figure 6 It is the step flow chart of the accurate determination method of the total hydrogen content in the water body containing ultra-fine hydrogen bubbles of the present invention. Figure 6 It includes Step 1, sealing the water sample containing ultra-fine bubbles to be tested in an anaerobic bottle; Step 2, using the freeze-thaw method to eliminate the ultra-fine bubbles in the water and release the gas in the bubbles to the headspace of the anaerobic bottle; Step 3, using gas chromatography to measure the hydrogen content in the headspace; Step 4, establishing a hydrogen calibration curve, and calculating the total hydrogen concentration in the water body by accurately measuring parameters such as the volume of the headspace gas in the bottle. Detailed implementation mode

[0037] The present invention will be described below with reference to the accompanying drawings ( Figures 1-6 ) and embodiments.

[0038] Figure 1 is a schematic diagram of the disassembly and combination of a water sample sealing device involved in an accurate determination method for the total hydrogen content in a water body containing hydrogen ultrafine bubbles according to the present invention. Figure 2 is an actual change diagram of the color of a water sample during the titration process involved in an accurate determination method for the total hydrogen content in a water body containing hydrogen ultrafine bubbles according to the present invention. Figure 3 is a schematic diagram of the extraction of headspace gas involved in an accurate determination method for the total hydrogen content in a water body containing hydrogen ultrafine bubbles according to the present invention. Figure 4 is a schematic process diagram of an accurate determination method for the total hydrogen content in a water body containing hydrogen ultrafine bubbles according to the present invention. Figure 5 is a calibration curve of standard hydrogen involved in an accurate determination method for the total hydrogen content in a water body containing hydrogen ultrafine bubbles according to the present invention. Figure 6 is a step flow chart of an accurate determination method for the total hydrogen content in a water body containing hydrogen ultrafine bubbles according to the present invention. Refer to Figures 1 to 6 As shown, an accurate determination method for the total hydrogen content in a water body containing hydrogen ultrafine bubbles is characterized by high sensitivity, accuracy, convenience for popularization and application, etc., and the dissolved hydrogen concentration of the sample and the presence of oxidizing and reducing substances have no influence on the accuracy of the determination. The method comprises the following steps:

[0039] (1) Seal the water sample containing hydrogen ultrafine bubbles in an anaerobic bottle, and the anaerobic bottle is sealed with a hydrogen butyl rubber and an aluminum cap to prevent hydrogen from escaping from the bottle. Before sealing the water sample, take a certain amount of the water sample and titrate and determine the dissolved hydrogen in the water sample using a methylene blue platinum colloid reagent to estimate the dissolved hydrogen content;

[0040] (2) Use the freeze-thaw technique to release the dissolved hydrogen molecules and the hydrogen existing in the form of ultrafine bubbles in the water sample from the liquid phase to the headspace of the anaerobic bottle;

[0041] (3) Use gas chromatography to determine the percentage of hydrogen in the headspace of the anaerobic bottle;

[0042] (4) Accurately determine the volume of the water sample, the headspace volume, the air pressure in the bottle and the measurement temperature in the anaerobic bottle, and accurately calculate the total hydrogen content in the water sample through a formula.

[0043] In step 1), according to the principle of thermal expansion and contraction, to ensure that there is sufficient space in the anaerobic bottle after freezing and prevent the bottle body from bursting, the volume of the hydrogen ultra-fine bubble water needs to be controlled below 80% of the volume of the anaerobic bottle. Before sealing the water sample, 6 mL of the water sample is separated and titrated with methylene blue platinum reagent. To prevent uneven dropper volume, a pipette gun is used to add the methylene blue platinum colloid reagent to the water sample (20 μL each time, and the sampling range of the pipette gun is 0–20 μL).

[0044] In step 2), to avoid the bottle body from cracking due to sudden temperature drop and uneven stress during the freezing process, first, the anaerobic bottle filled with hydrogen ultra-fine bubble water is placed horizontally in a 4°C refrigerator for 12 hours. Then, the anaerobic bottle is transferred to a -20°C refrigerator and placed for more than 24 hours to ensure that the liquid sample undergoes a phase change and becomes solid ice. Finally, the sample is thawed at room temperature to restore it to a liquid state.

[0045] In step 3), when using a capillary column, the recommended operating conditions are as follows: a) Carrier gas: argon or helium, constant flow mode, and the measured flow rate at the column outlet is 12 mL / min; b) Gas injection volume: 0.2 mL; c) Chromatographic column: molecular sieve (model Msieve5A), length 30 m, outer diameter 0.53 mm, inner diameter 50 μm; d) Column temperature: 100°C; e) Thermal conductivity detector (TCD) temperature: 110°C.

[0046] When using a packed column, the recommended operating conditions are as follows: a) Carrier gas: argon or helium, constant flow mode, and the measured flow rate at the column outlet is 30 mL / min; b) Gas injection volume: 1 ml; c) Chromatographic column: molecular sieve (model MolSieve 5A), length 1.83 m, outer diameter 3.1 mm, inner diameter 2 mm, mesh 60 - 80; d) Column temperature: 60°C.

[0047] In step 4), the total volume V of the anaerobic bottle water is calculated as follows:

[0048]

[0049] where M a is the mass of the anaerobic bottle containing a specific amount of ultra-fine bubble dispersion liquid;

[0050] M b is the mass of the anaerobic bottle;

[0051] ρ is the density of ultrapure water.

[0052] The volume V of the headspace gas in the anaerobic bottle after injecting the sample gas is calculated as follows:

[0053]

[0054] Among them, V total is the total volume of the anaerobic bottle;

[0055] V water is the volume of the liquid sample;

[0056] M T is the mass of ultrapure water corresponding to when the anaerobic bottle is filled with ultrapure water.

[0057] Convert the hydrogen percentage content data obtained by gas chromatography into hydrogen concentration. The unit conversion equation from volume % to mol / m 3 is as follows. Assume the gas is an ideal gas and the gas pressure P is 1 atm.

[0058]

[0059] Among them, i is the gas component (hydrogen)

[0060] C i is the gas component concentration (mol / m 3 or %);

[0061] C i , ％ is the volume percentage concentration (%) of the gas component

[0062] is the molar concentration (mol / m 3 )

[0063] n is the number of moles of the gas (g / mol);

[0064] n i is the number of moles of the gas component (g / mol)

[0065] P0 is the standard atmospheric pressure (1 atm);

[0066] T0 is the standard temperature (273.15 K);

[0067] P is the gas pressure (atm) in the headspace of the anaerobic bottle;

[0068] V is the headspace volume (mL) of the anaerobic bottle;

[0069] R is the gas constant (R = 8.20544×10 -5 m 3 atm / mol K);

[0070] T is the detection temperature (K).

[0071] The calculation formula for the hydrogen concentration in the water sample is as follows:

[0072]

[0073] Among them, is the molar mass of hydrogen (2.01588 g / mol)

[0074] This method can detect water samples containing ultrafine bubbles, verify the accuracy of the test model and provide data support for the further optimization of the model.

[0075] An accurate determination method for the total hydrogen content in a water body containing ultrafine hydrogen bubbles, this method includes the following steps:

[0076] Step 1, seal the water sample containing ultrafine hydrogen bubbles to be tested in an anaerobic bottle; Step 2, use the freeze-thaw technique to release the hydrogen in the ultrafine bubbles in the water sample into the headspace of the anaerobic bottle; Step 3, use a gas chromatograph to measure the percentage of hydrogen in the headspace of the anaerobic bottle; Step 4, accurately measure the volume of the water sample, the headspace volume, the air pressure in the bottle and the measurement temperature in the anaerobic bottle, and calculate the total hydrogen content in the water sample through a formula. The method proposed by the present invention has no requirements for the dissolved hydrogen concentration of the sample and the presence or absence of oxidizing and reducing substances in the water sample, and has the advantages of high sensitivity, accuracy, convenient popularization and application, etc.

[0077] This method stipulates the evaluation method for the hydrogen content in the ultrafine bubble dispersion. The oxidation titration method can be used as a method for quickly determining the hydrogen content in the ultrafine bubble dispersion, with a detection limit of 0.1 mg / L and an accurate range between 0.2 mg / L and 1.6 mg / L. The presence of oxidizing or reducing substances in the dispersion affects the measurement accuracy, and it is recommended to be used only as a rough estimation method. The gas chromatography method has a quite high accuracy range and the lowest detection limit, and the presence of ultrafine bubbles in water does not affect the measurement result. The presence of oxidizing or reducing substances in water also does not affect the measurement accuracy.

[0078] An accurate determination method for the total hydrogen content in a water body containing ultrafine hydrogen bubbles, including the following steps;

[0079] (1) A series of hydrogen ultra-fine bubble waters with different bubble number densities were prepared using the dilution effect of hydrogen water. Among them, hydrogen ultra-fine bubble water and hydrogen-rich water (without ultra-fine bubbles) were prepared by a hydrogen ultra-fine bubble generator (NB-T71A, Shanghai Nami Barber Nano Technology Co., Ltd.) and a hydrogen generator (SPH-300A, Beijing Zhonghui Pu Analysis Technology Co., Ltd.) respectively. The volume mixing ratios of hydrogen ultra-fine bubble water and hydrogen-rich water were set to 1, 0.8, 0.6, 0.4, 0.2, and 0. According to the principle of volume expansion when liquid freezes into solid, to ensure sufficient space in the anaerobic bottle after freezing and prevent the bottle body from bursting, the ratio of the liquid volume to the headspace volume in the small bottle needs to be controlled between 2:1 and 5:1. For example, the liquid volume in a 100 mL small bottle should be less than 80 mL. Therefore, the volume of hydrogen ultra-fine bubble water was controlled between 70 - 80 mL and sealed in an anaerobic bottle with a butyl rubber stopper, an aluminum cap, and a bottle opener ( Figure 1 ). Before sealing, 6 mL of the corresponding hydrogen ultra-fine bubble water sample was separated and titrated with methylene blue platinum colloid gold colloid reagent until the solution changed from blue to colorless ( Figure 2 ). To prevent uneven dropper volume, a pipette gun with a volume range of 0–20 μL was used to add the methylene blue platinum colloid reagent to the water sample (20 μL each time).

[0080] (2) According to the freeze-thaw method in ISO 24261-2, the ultra-fine bubbles in water were eliminated. To avoid the anaerobic bottle from bursting during freezing, it is best to use the step-by-step freezing method, and the anaerobic bottle should be kept horizontally placed. First, the anaerobic bottle containing the ultra-fine bubble dispersion was horizontally placed in a 4 °C refrigerator for 12 hours. Secondly, the anaerobic bottle was transferred to a -20 °C refrigerator and frozen for more than 24 hours to ensure that all the liquid became solid. Finally, the sample was thawed at room temperature. After the sample temperature stabilized, a specific volume of headspace gas was accurately extracted using a manual closed injection needle ( Figure 3 ). The bubble number density before and after freeze-thaw was tracked and analyzed using a nanoparticle analyzer (NTA, Nanoparticle Tracking Analysis) to investigate its elimination efficiency.

[0081] (3) The extracted headspace gas was injected into a gas chromatograph for detection ( Figure 4 ). The flow rate of argon (carrier gas) was controlled by a mass flow controller. The TCD (thermal conductivity detector) of the gas chromatograph could convert the separated gas components into electrical signals and send the electrical signals to a signal processing device (computer) to obtain the peaks corresponding to the separated gas components and convert them into the molar concentration of the gas.

[0082] Standard hydrogen can be purchased from a natural gas company or generated using a hydrogen generator. The contents of standard hydrogen in the calibration gas are 0.5%, 1%, 5%, 10%, 20%, 50%, and 100% in sequence. Use a syringe with a sealed plug to accurately extract 0.2 ml of headspace gas for the experiment.

[0083] (4) To accurately measure the total amount of hydrogen in a hydrogen UFB (Ultra Fine Bubble, referring to bubbles with a particle size ≤ 1 μm) dispersion, a standard curve for the relationship between hydrogen concentration and hydrogen peak area in gas chromatography needs to be established. The calibration curve is used for standard hydrogen with known percentages of 1%, 5%, 10%, 20%, 40%, 60%, and 80%. Both capillary columns and packed columns can be used. Since the injection volume of the capillary column is small, it can reduce and avoid changes in the headspace volume, thereby reducing experimental errors. The calibration curve of hydrogen concentration is as Figure 5 shown, so the peak area signal of hydrogen can be converted into the hydrogen percentage concentration using the non-linear equation in the standard curve.

[0084] Use the weighing method to accurately calculate the volume of the solution in the anaerobic bottle. The calculation formula for the total volume of the anaerobic bottle is as follows:

[0085]

[0086] where M a is the mass of the anaerobic bottle containing a specific amount of ultrafine bubble dispersion;

[0087] M b is the mass of the anaerobic bottle;

[0088] ρ is the density of ultrapure water.

[0089] Use the weighing method to accurately calculate the volume of the headspace gas in the anaerobic bottle. The calculation formula is as follows:

[0090]

[0091] where V total is the total volume of the anaerobic bottle;

[0092] V water is the volume of the liquid sample;

[0093] M T is the mass of the ultrapure water corresponding to when the anaerobic bottle is filled with ultrapure water.

[0094] Convert the hydrogen percentage content data obtained by gas chromatography into hydrogen concentration. The unit conversion equation from % to mol / m3 is shown as follows. Assume the gas is an ideal gas and the gas pressure (P) is 1 atm.

[0095]

[0096] Among them, C i is the gas component concentration (mol / m 3 or %);

[0097] n is the number of moles of the gas (g / mol);

[0098] P0 is the standard atmospheric pressure (1 atm);

[0099] T0 is the standard temperature (273.15 K);

[0100] P is the gas pressure at the headspace of the anaerobic bottle (atm);

[0101] V is the headspace volume of the anaerobic bottle (mL);

[0102] R is the gas constant (R = 8.20544×10- 5 m 3 atm / mol K);

[0103] T is the detection temperature (K).

[0104] According to the ideal gas equation PV = nRT, at a certain pressure and temperature, the total number of moles of hydrogen in the headspace (n) can be calculated using the headspace volume in the anaerobic bottle. Furthermore, the hydrogen concentration in the water sample can be calculated, and the calculation formula is as follows:

[0105]

[0106] Among them, is the molar mass of hydrogen (2.01588 g / mol)

[0107] Implementation case - Relationship between hydrogen content and number concentration of ultrafine bubbles and dissolved hydrogen

[0108] The measurement results of hydrogen concentration of 17 liquid samples containing different ultrafine bubble concentrations are shown in Table 1. For the elimination effect of ultrafine bubbles, the freeze-thaw method is effective and the removal rate is above 99%.

[0109] Table 1 - Measurement of hydrogen content in different UFB dispersions by two methods

[0110]

[0111] The analysis results of samples No. 1 to No. 12 in Table 1 are an example of measuring the hydrogen content in hydrogen ultrafine bubble water by titration method and gas chromatography. Hydrogen water and hydrogen ultrafine bubble water are mixed in different proportions to obtain hydrogen water samples with different bubble concentrations. The ultrafine bubble concentration and bubble size distribution are analyzed by a nanoparticle analyzer. The measurement results of dissolved hydrogen content in different samples are similar to those measured by the oxidation titration method. When the ultrafine bubble concentration is lower than 2.0×107 When the bubble concentration is higher than 2.0×10 7 The above implementation cases show that the method of the present invention, which uses gas chromatography combined with titration to detect the hydrogen concentration in a liquid containing ultrafine bubbles, can accurately and effectively detect the total hydrogen content in water. At the same time, the method is not limited by the nature of the sample and has the characteristics of accuracy, effectiveness, simple operation, and easy implementation.

[0112] The contents not described in detail in the specification of the present invention belong to the prior art known to the professional and technical personnel in the field. It is pointed out here that the above description helps those skilled in the art to understand the invention, but does not limit the protection scope of the invention. Any equivalent replacement, modification and / or simplification of the above description without departing from the essence of the invention falls within the protection scope of the invention.

Claims

1. An accurate determination method for the total hydrogen content in a water body containing ultrafine hydrogen bubbles, characterized in that, It includes the following steps: Step 1: Seal the water sample to be tested containing ultrafine hydrogen bubbles in an anaerobic bottle; Step 2: Use the freeze-thaw technique to release the hydrogen in the ultrafine bubbles in the water sample into the headspace inside the anaerobic bottle; Step 3: Use a gas chromatograph to measure the hydrogen content in the headspace; Step 4: Determine the total hydrogen content in the water sample according to the volume of the water sample, the headspace volume, the air pressure and the temperature in the anaerobic bottle; The water sample volume V in step 4 water and the headspace volume V gas are calculated by the following formulas: Where Ma is the mass of the anaerobic bottle containing the water sample to be measured, Mb is the mass of the empty anaerobic bottle, ρ is the density of ultrapure water, and V total is the total volume of the anaerobic bottle, and M T is the mass of ultrapure water corresponding to when the anaerobic bottle is filled with ultrapure water; In step 4, it includes converting the headspace hydrogen content obtained by the gas chromatograph from volume % to mol / m 3 , and the conversion formula is as follows: where i is the gas component hydrogen; C i is the hydrogen concentration; C i，％ is the hydrogen volume percentage concentration; is the hydrogen molar concentration mol / m 3 ; n is the mole number of the headspace gas g / mol; n i is the mole number of hydrogen g / mol; P0 is the standard atmospheric pressure 1 atm; T0 is the standard temperature 273.15 K; P is the headspace gas pressure atm; V is the headspace volume mL; R is the gas constant, R = 8.20544×10 -5 m 3 atm / mol K; T is the headspace gas temperature K; In step 4, the total hydrogen content in the water sample is calculated using the following formula wherein is the molar mass of hydrogen gas, 2. The accurate determination method of the total hydrogen content in the water body containing ultrafine hydrogen bubbles according to claim 1, characterized in that In Step 1, it includes: before sealing the water sample, take a certain amount of the water sample and titrate the dissolved hydrogen in the water sample using methylene blue platinum colloid reagent to estimate the dissolved hydrogen content; then seal the water sample to be tested containing ultrafine hydrogen bubbles in an anaerobic bottle through a butyl rubber stopper, an aluminum cap and an opener, and the volume of the water sample to be tested accounts for ≤80% of the volume of the anaerobic bottle.

3. The accurate determination method of the total hydrogen content in the water body containing ultrafine hydrogen bubbles according to claim 1, characterized in that, The freeze-thaw technique in Step 2 includes the following steps: Step 2a: Place the anaerobic bottle horizontally in a refrigerator at 4°C for 12 hours; Step 2b: Transfer the anaerobic bottle to a refrigerator at -20°C and place it for a time ≥24 hours to ensure that the water sample to be tested undergoes a phase change and becomes solid ice; Step 2c: Thaw the solid ice water sample to be tested at room temperature to make it return to the liquid water sample to be tested.

4. The accurate determination method of the total hydrogen content in the water body containing ultrafine hydrogen bubbles according to claim 1, characterized in that, In Step 3, it includes using a capillary column or a packed column to measure the hydrogen content in the headspace; The operating conditions for using a capillary column are as follows: a) Carrier gas: argon or helium, constant flow mode, the measured flow rate at the column outlet is 12 mL / min; b) Gas injection volume: 0.2 mL; c) Chromatographic column: molecular sieve of model Msieve5A, 30 m long, 0.53 mm outer diameter, 50 μm inner diameter; d) Column temperature: 100°C; e) Thermal conductivity detector TCD temperature 110°C; The operating conditions for using a packed column are as follows: a) Carrier gas: argon or helium, constant flow mode, the measured flow rate at the column outlet is 30 mL / min; b) Gas injection volume: 1 ml; c) Chromatographic column: molecular sieve of model Msieve5A, 1.83 m long, 3.1 mm outer diameter, 2 mm inner diameter, mesh 60 - 80 mesh; d) Column temperature 60°C.

5. The accurate determination method of the total hydrogen content in the water body containing ultrafine hydrogen bubbles according to claim 1, characterized in that, In Step 3, it includes establishing a calibration curve for the relationship between the hydrogen concentration and the hydrogen peak area in gas chromatography, and the calibration curve is used for standard hydrogen with known percentages of 1%, 5%, 10%, 20%, 40%, 60% and 80%, and uses the non-linear equation in the standard curve to convert the peak area signal of hydrogen into the hydrogen percentage concentration.

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