CN116338036A - Accurate determination method for total hydrogen content in water body containing hydrogen ultrafine bubbles - Google Patents

Accurate determination method for total hydrogen content in water body containing hydrogen ultrafine bubbles Download PDF

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CN116338036A
CN116338036A CN202310154414.9A CN202310154414A CN116338036A CN 116338036 A CN116338036 A CN 116338036A CN 202310154414 A CN202310154414 A CN 202310154414A CN 116338036 A CN116338036 A CN 116338036A
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hydrogen
water sample
water
headspace
volume
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柳姝
包涵
范文宏
张优
吕爽
杨晓龙
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Beihang University
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Abstract

The invention discloses a method for accurately measuring the total hydrogen content in a water body containing hydrogen ultrafine bubbles, which comprises the following steps: step 1, sealing a water sample to be detected containing hydrogen ultrafine bubbles in an anaerobic bottle; step 2, releasing hydrogen in ultra-fine bubbles in the water sample to the headspace of the anaerobic bottle by utilizing a freeze thawing technology; step 3, determining the percentage of hydrogen in the headspace of the anaerobic bottle by using a gas chromatograph; and 4, accurately measuring the volume of the water sample in the anaerobic bottle, the headspace volume, the air pressure in the bottle and the measured temperature, and calculating the total hydrogen content in the water sample through a formula. The method provided by the invention has no requirement on the concentration of dissolved hydrogen in the sample, and whether redox substances exist in the water sample or not, and has the advantages of high sensitivity, accuracy, convenience in popularization and application and the like.

Description

Accurate determination method for total hydrogen content in water body containing hydrogen ultrafine bubbles
Technical Field
The invention relates to the technical field of hydrogen concentration measurement in a hydrogen-containing water bubble dispersed phase, in particular to an accurate measurement method for total hydrogen content in a water body containing hydrogen ultrafine bubbles.
Background
Hydrogen molecules are recognized as ideal biological antioxidants due to their unique properties of selective oxidation resistance, strong diffusion, biosafety, etc., and are used to relieve 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 the tolerance of plants to external stress, and are widely used in the fields of medicine, botanic and agronomy. However, the use of hydrogen molecules has difficulties, mainly in that their high diffusivity significantly reduces their solubility in water and residence time. Therefore, searching for an efficient technical method, and prolonging the residence time of hydrogen as much as possible while dissolving hydrogen in water quickly becomes a challenging key problem for the large-scale application of hydrogen molecules in the water environment field.
In recent years, the discovery of ultra-fine bubble technology and the appearance of related technical methods open up a new research path for solving the bottleneck problem of hydrogen molecules in water environment, medicine and agriculture application. Compared with the common dissolved hydrogen molecules, the hydrogen molecules in the form of ultrafine bubbles have a number of unique properties and application advantages, which are mainly represented in the following two aspects: first, the ultra-fine bubbles have a large specific surface area and a negatively charged surface, thereby greatly improving the solubility and dissolution time of hydrogen in water. Second, the interior of the ultra-fine bubbles is an extreme environment of high pressure and high density, thereby leading to the hydrogen molecules in the ultra-fine bubbles having higher activity and stronger ability to remove free radicals.
The hydrogen concentration is a key indicator in hydrogen applications, and thus accurate determination of hydrogen concentration is particularly important. Current methods for measuring hydrogen content in water include oxidative titration and gas chromatography using methylene blue platinum colloidal reagent; however, the ultra-fine bubbles have a great influence on the measurement result of the hydrogen content in water, and the existing method may cause great errors in the result because the influence factors of the ultra-fine bubbles are not considered.
Disclosure of Invention
Aiming at the defects in the prior art, the invention provides an accurate determination method for the total hydrogen content in a water body containing hydrogen ultrafine bubbles.
The technical scheme of the invention is as follows:
the accurate determination method for the total hydrogen content in the water body containing the hydrogen ultrafine bubbles is characterized by comprising the following steps of:
step 1, sealing a water sample to be tested containing hydrogen ultrafine bubbles in an anaerobic bottle;
step 2, releasing hydrogen in ultra-fine bubbles in the water sample to the headspace in the anaerobic bottle by utilizing a freeze thawing technology;
step 3, measuring the content of the headspace hydrogen by using a gas chromatograph;
and 4, determining the total hydrogen content in the water sample according to the volume, the headspace volume, the air pressure and the temperature of the water sample in the anaerobic bottle.
The step 1 includes: before sealing a water sample, taking a certain amount of water sample, and carrying out titration measurement on dissolved hydrogen of the water sample by using a methylene blue platinum colloidal reagent to estimate the content of the dissolved hydrogen; then the water sample to be detected containing hydrogen ultrafine bubbles is sealed in an anaerobic bottle through a butyl rubber plug, an aluminum cover and a bottle opener, and the volume of the water sample to be detected is less than or equal to 80% of the volume of the anaerobic bottle.
The freeze thawing technique in the step 2 comprises the following steps: step 2a, horizontally placing the anaerobic bottle in a refrigerator at 4 ℃ for 12 hours; step 2b, transferring the anaerobic bottle into a refrigerator at the temperature of minus 20 ℃ for more than or equal to 24 hours to ensure that the water sample to be tested changes phase and becomes solid ice; and 2c, thawing the solid ice water sample to be detected at room temperature to restore the solid ice water sample to be detected into a liquid water sample to be detected.
The step 3 comprises the steps of adopting a capillary column or a packed column to measure the content of the headspace hydrogen; the operating conditions for the capillary column were as follows: a) Carrier gas: argon or helium, constant flow mode, and measuring flow of the column outlet of 12mL/min; b) Gas sample injection amount: 0.2mL; c) Chromatographic column: molecular sieve of model Msieve5A, 30m long, 0.53mm outside diameter and 50 μm inside diameter; d) Column temperature: 100 ℃; e) The TCD temperature of the thermal conductivity detector is 110 ℃; the operating conditions for the packed column were as follows: a) Carrier gas: argon or helium, constant flow mode, measuring flow rate at the column outlet of 30mL/min; b) Gas sample injection amount: 1ml; c) Chromatographic column: molecular sieve with model Msieve5A, length of 1.83m, outer diameter of 3.1mm, inner diameter of 2mm, mesh of 6080 mesh; d) Column temperature 60 ℃.
The water sample volume V in the step 4 water And a headspace volume V gas The calculation formula of (2) is as follows:
Figure BDA0004092638330000021
Figure BDA0004092638330000022
wherein Ma is the mass of an anaerobic bottle containing a water sample to be detected, mb is the mass of an empty anaerobic bottle, ρ is the density of ultrapure water, and V total Is the total volume of the anaerobic bottle, M T The quality of the ultrapure water corresponding to the filling of the anaerobic bottle with the ultrapure water.
The step 4 comprises the step of converting the headspace hydrogen content obtained by a gas chromatograph from volume percent to mol/m 3 The conversion formula is as follows:
Figure BDA0004092638330000023
wherein i is a gaseous component hydrogen; c (C) i Is the hydrogen concentration; c (C) i，％ Is the volume percentage concentration of hydrogen;
Figure BDA0004092638330000024
is the molar concentration of hydrogen mol/m 3 The method comprises the steps of carrying out a first treatment on the surface of the n is the mole number g/mol of the headspace gas; n is n i Is the mole number g/mol of hydrogen；P 0 Is a standard atmospheric pressure latm; t (T) 0 A standard temperature of 273.15K; p is headspace gas pressure atm; v is the headspace volume mL; r is a gas constant, r= 8.20544 ×10 -5 m 3 atm/mol K; t is the headspace gas temperature K.
The step 4 comprises the following formula to calculate the total hydrogen content in the water sample
Figure BDA0004092638330000031
Figure BDA0004092638330000032
Wherein the method comprises the steps of
Figure BDA0004092638330000033
Molar mass of hydrogen, +.>
Figure BDA0004092638330000034
The step 3 comprises the step of establishing a calibration curve of the relation between the hydrogen concentration and the hydrogen peak area in the gas chromatograph, wherein the calibration curve is used for standard hydrogen with known percentages of 1%,5%,10%,20%, 40%, 60% and 80%, and the peak area signal of the hydrogen is converted into the percentage concentration of the hydrogen by using a nonlinear equation in the standard curve.
The invention has the following technical effects: the method for accurately measuring the total hydrogen content in the water body containing the hydrogen ultrafine bubbles can accurately measure the total hydrogen concentration in the water by utilizing a gas chromatography headspace method, has no requirement on the dissolved hydrogen concentration of a sample and the existence or non-existence of redox substances in the water sample, and has the advantages of high sensitivity, accuracy, convenience in popularization and application and the like.
The technical method of the invention has the following advantages:
(1) The method does not require the presence or absence of dissolved oxygen and contained redox substances in the sample.
(2) The method has no requirement on the concentration range of the hydrogen content in the sample, and the measurement result is accurate.
(3) The method can simultaneously measure dissolved hydrogen molecules in water and hydrogen molecules existing in the form of ultrafine bubbles.
Drawings
FIG. 1 is a schematic diagram of the decomposition and combination of a water sample sealing device involved in the implementation of the method for accurately measuring the total hydrogen content in a water body containing hydrogen ultrafine bubbles. In fig. 1, the device comprises a butyl rubber plug A, an aluminum cover B, an empty anaerobic bottle C, a closed water sample anaerobic bottle D and a cover opener E. In the process of sealing or closing the water sample, the water sample is put into an empty anaerobic bottle C, a butyl rubber plug A covers the bottle mouth, and an aluminum cap B is packaged on the bottle mouth by a cap device E.
FIG. 2 is a graph showing actual color change of a water sample during titration, which is involved in implementing the method for accurately measuring the total hydrogen content in a water body containing hydrogen ultrafine bubbles. The left graph, the middle graph and the right graph are included in fig. 2, wherein the left graph is the condition of adding methylene blue into a water sample, the middle graph is the condition that the added blue methylene blue is reduced to be colorless by hydrogen molecules, and the right graph is the condition that a titration end point solution is changed to be blue. The content of dissolved hydrogen in the water sample can be estimated by titration determination of the dissolved hydrogen in the water sample.
FIG. 3 is a schematic drawing of headspace gas extraction involved in practicing the accurate determination method of total hydrogen content in a hydrogen-containing ultra-fine bubble water body of the present invention. In fig. 3, the headspace gas above the water sample G in the closed water sample anaerobic bottle D is extracted by the sample injection needle F.
FIG. 4 is a flow chart of a method for accurately measuring the total hydrogen content in a water body containing hydrogen ultrafine bubbles. Sample preservation, bubble elimination and gas phase analysis are included in fig. 4. The sample preservation comprises the steps of sealing a water sample to be detected containing hydrogen ultra-fine bubbles in an anaerobic bottle, wherein the lower half part in the anaerobic bottle is an ultra-fine bubble disperse phase, and the upper half part in the anaerobic bottle is air. In the bubble elimination, a freeze thawing technology is adopted to release dissolved hydrogen molecules in a water sample and hydrogen existing in the form of ultra-fine bubbles from a liquid phase to the headspace of an 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, and the method comprises the following steps: step 1, horizontally placing an anaerobic bottle filled with hydrogen ultrafine bubble water in a refrigerator at 4 ℃ for 12 hours; step 2, transferring the anaerobic bottle into a refrigerator at the temperature of minus 20 ℃ and placing for more than 24 hours to ensure that the liquid sample is subjected to phase change and becomes solid ice; and 3, thawing the sample at room temperature to restore the liquid state. The gas phase analysis comprises injecting the headspace gas extracted by the sample needle into a detector through a sample injection hole, wherein the detector is connected with an argon bottle through an MFC (Mass Flow Controller, gas mass flow controller), the detector is provided with a display, the display displays gas chromatography, gas phase analysis parameters comprise flow rate=12 ml/min, sample injection volume=0.2 ml, column temperature=100 ℃, and detector temperature=110 ℃.
FIG. 5 is a calibration curve of standard hydrogen involved in practicing the accurate determination method of total hydrogen content in a body of water containing hydrogen ultra-fine bubbles of the present invention. In FIG. 5, the response intensity (Y-axis, dimensionless) is plotted on the ordinate, and 6e+06 represents 6X10 6 The abscissa in the large scale is the retention time (X axis, min) and the abscissa in the small scale is the standard concentration (X' axis, vol%). The curves in the large coordinates are from top to bottom for gas chromatography of standard hydrogen with different volume concentrations (100% -50% -20% -10% -5% -1% -0.5%). The X-axis represents retention time (min), the Y-axis represents detection response intensity (dimensionless), and X' represents standard concentration (vol%) with the formula y= 11.3052X 3 -3023.59X 2 +558840X, r2=0.9999, where X represents the standard concentration.
FIG. 6 is a flow chart of steps for implementing the method for accurately measuring the total hydrogen content in the water body containing hydrogen ultrafine bubbles. FIG. 6 includes step 1, sealing a water sample to be tested containing ultrafine bubbles in an anaerobic bottle; step 2, removing ultrafine bubbles in water by using a freeze thawing method, and releasing gas in the bubbles into the top of the anaerobic bottle; step 3, measuring the content of the headspace hydrogen by utilizing a gas chromatography; and 4, establishing a hydrogen calibration curve, and calculating the total concentration of hydrogen in the water body by accurately measuring parameters such as the volume of the air body at the top of the bottle.
Detailed Description
The invention is described below with reference to the figures (fig. 1-6) and examples.
FIG. 1 is a schematic diagram of the decomposition and combination of a water sample sealing device involved in the implementation of the method for accurately measuring the total hydrogen content in a water body containing hydrogen ultrafine bubbles. FIG. 2 is a graph showing actual color change of a water sample during titration, which is involved in implementing the method for accurately measuring the total hydrogen content in a water body containing hydrogen ultrafine bubbles. FIG. 3 is a schematic drawing of headspace gas extraction involved in practicing the accurate determination method of total hydrogen content in a hydrogen-containing ultra-fine bubble water body of the present invention. FIG. 4 is a flow chart of a method for accurately measuring the total hydrogen content in a water body containing hydrogen ultrafine bubbles. FIG. 5 is a calibration curve of standard hydrogen involved in practicing the accurate determination method of total hydrogen content in a body of water containing hydrogen ultra-fine bubbles of the present invention. FIG. 6 is a flow chart of steps for implementing the method for accurately measuring the total hydrogen content in the water body containing hydrogen ultrafine bubbles. Referring to fig. 1 to 6, the accurate determination method for total hydrogen content in a water body containing hydrogen ultrafine bubbles is characterized by the advantages of high sensitivity, accuracy, convenience in popularization and application and the like, and has no influence on the accuracy of determination on the dissolved hydrogen concentration of a sample and the existence of oxidative and reductive substances. The method comprises the following steps:
(1) And (3) sealing a water sample containing hydrogen ultrafine bubbles in an anaerobic bottle, wherein the anaerobic bottle is sealed by utilizing hydrogen butyl rubber and an aluminum cover, so that the hydrogen is prevented from escaping from the bottle. Before sealing a water sample, taking a certain amount of water sample, and carrying out titration measurement on dissolved hydrogen of the water sample by using a methylene blue platinum colloidal reagent to estimate the content of the dissolved hydrogen;
(2) Releasing the dissolved hydrogen molecules in the water sample and hydrogen existing in the form of ultra-fine bubbles from the liquid phase to the headspace of the anaerobic bottle by utilizing a freeze thawing technology;
(3) Determining the percentage of hydrogen in the headspace of the anaerobic bottle by utilizing gas chromatography;
(4) The volume of the water sample in the anaerobic bottle, the headspace volume, the air pressure in the bottle and the measured temperature are accurately determined, and the total hydrogen content in the water sample is accurately calculated through a formula.
In the step 1), according to the principle of thermal expansion and cold contraction, in order to ensure that the space in the anaerobic bottle is sufficient after freezing and the bottle body is not burst, the volume of the hydrogen ultra-fine bubble water is controlled to be less than 80% of the volume of the anaerobic bottle. And (3) separating and taking 6mL of water sample before sealing the water sample, titrating with a methylene blue platinum reagent, and adding the methylene blue platinum colloidal reagent into the water sample by using a pipette (20 mu L each time and a sampling range of the pipette is 0-20 mu L) in order to prevent the volume of the dropper from being uneven.
In the step 2), in order to avoid the rupture of the bottle body caused by the sudden temperature drop and uneven stress in the freezing process, the anaerobic bottle filled with the hydrogen ultrafine bubble water is firstly horizontally placed in a refrigerator at 4 ℃ for 12 hours. Then the anaerobic bottle is transferred to a refrigerator with the temperature of minus 20 ℃ for more than 24 hours to ensure that the liquid sample is subjected to phase change and becomes solid ice, and finally the sample is thawed at room temperature to recover the liquid state.
In the step 3), when a capillary column is used, recommended operation conditions are as follows, a) carrier gas is argon or helium, a constant flow mode is adopted, and the measuring flow of a column outlet is 12mL/min; b) The gas sample injection amount is 0.2mL; c) A chromatographic column, namely a molecular sieve (model Msieve 5A), which has the length of 30m, the outer diameter of 0.53mm and the inner diameter of 50 mu m; d) Column temperature is 100 ℃; e) Thermal Conductivity Detector (TCD) temperature 110 ℃.
When the packed column is used, recommended operating conditions are a) carrier gas, argon or helium, constant flow mode, and column outlet measurement flow rate of 30mL/min; b) The gas sample injection amount is 1ml; c) A chromatographic column, namely a molecular sieve (model MolSieve 5A), which has the length of 1.83m, the outer diameter of 3.1mm, the inner diameter of 2mm and the mesh size of 60-80 meshes; d) Column temperature 60 ℃.
In the step 4), the total volume V of the anaerobic bottle water The calculation formula of (2) is as follows:
Figure BDA0004092638330000051
wherein M is a The mass of the anaerobic bottle containing a specific amount of ultrafine bubble dispersion liquid;
M b the quality of the anaerobic bottle;
ρ is the density of ultrapure water.
Anaerobic bottle top air volume V after sample injection gas The calculation formula is as follows:
Figure BDA0004092638330000061
wherein V is total The total volume of the anaerobic bottle;
V water is the volume of the liquid sample;
M T the quality of the ultrapure water corresponding to the filling of the anaerobic bottle with the ultrapure water.
Conversion of percentage hydrogen data from gas chromatography to hydrogen concentration, from volume% to mol/m 3 The unit conversion equation of (2) is shown below. Assuming that the gas is an ideal gas, the gas pressure P is 1atm.
Figure BDA0004092638330000062
Wherein i is a gas component (hydrogen)
C i Is the concentration of the gas component (mol/m) 3 Or%);
C i ， ％ is the volume percent concentration (%)
Figure BDA0004092638330000063
Is the molar concentration (mol/m) of the gas component 3 )
n is the number of moles of gas (g/mol);
n i is the number of moles (g/mol) of the gas component
P 0 Is standard atmospheric pressure (1 atm);
T 0 is at standard temperature (273.15K);
p is the gas pressure (atm) of the headspace of the anaerobic bottle;
v is the headspace volume (mL) of the anaerobic bottle;
r is a gas constant (r= 8.20544 ×10) -5 m 3 atm/mol K)；
T is the detection temperature (K).
The calculation formula of the hydrogen concentration in the water sample is as follows:
Figure BDA0004092638330000064
wherein, the liquid crystal display device comprises a liquid crystal display device,
Figure BDA0004092638330000065
is the molar mass of hydrogen (2.01588 g/mol)
The method can detect the water sample containing the ultrafine bubbles, check the accuracy of the model and provide data support for further optimization of the model.
An accurate determination method for total hydrogen content in a water body containing hydrogen ultrafine bubbles comprises the following steps:
step 1, sealing a water sample to be detected containing hydrogen ultrafine bubbles in an anaerobic bottle; step 2, releasing hydrogen in ultra-fine bubbles in the water sample to the headspace of the anaerobic bottle by utilizing a freeze thawing technology; step 3, determining the percentage of hydrogen in the headspace of the anaerobic bottle by using a gas chromatograph; and 4, accurately measuring the volume of the water sample in the anaerobic bottle, the headspace volume, the air pressure in the bottle and the measured temperature, and calculating the total hydrogen content in the water sample through a formula. The method provided by the invention has no requirement on the concentration of dissolved hydrogen in the sample, and whether redox substances exist in the water sample or not, and has the advantages of high sensitivity, accuracy, convenience in popularization and application and the like.
The method defines a method for evaluating the hydrogen content in the ultrafine bubble dispersion. The oxidation titration method can be used as a method for rapidly measuring the hydrogen content in the ultra-fine bubble dispersion, the detection limit is 0.1mg/L, the accurate range is between 0.2mg/L and 1.6mg/L, and the existence of oxidative or reductive substances in the dispersion affects the measurement accuracy and is suggested to be used as a rough estimation method only. Gas chromatography has a fairly high accuracy range and a minimum detection limit, and the presence of ultra-fine bubbles in water does not affect the measurement results. The presence of oxidizing or reducing substances in the water does not affect the measurement accuracy.
The accurate determination method of the total hydrogen content in the water body containing the hydrogen ultrafine bubbles comprises the following steps of;
(1) A series of hydrogen ultrafine bubble water containing different bubble number densities is prepared by utilizing the dilution effect of hydrogen water. The hydrogen ultrafine bubble water and the hydrogen-rich water (without ultrafine bubbles) are respectively prepared by a hydrogen ultrafine bubble generator (NB-T71A, shanghai nanometer haircut nanometer technology Co., ltd.) and a hydrogen generator (SPH-300A, beijing Zhonghui analysis technology Co., ltd.) and are set to have the volume mixing ratio of 1, 0.8, 0.6, 0.4, 0.2 and 0. According to the volume expansion principle of liquid phase freezing to solid phase, in order to ensure that the space in the anaerobic bottle is sufficient after freezing and the bottle body is not burst, the ratio of the liquid volume in the small bottle to the headspace volume is controlled between 2:1 and 5:1. For example, a 100 milliliter vial should contain less than 80 milliliters of liquid, thus controlling the hydrogen ultra-fine bubble water volume to between 70 and 80 milliliters and sealed in an anaerobic bottle by a butyl rubber stopper, aluminum cap, and bottle opener (fig. 1). Before sealing, 6mL of a corresponding hydrogen ultrafine bubble water sample was separated and titrated with a methylene blue platinum gold colloidal gold reagent until the solution changed from blue to colorless (fig. 2), and in order to prevent the volume of the dropper from being uneven, a pipette gun with a volume ranging from 0 to 20 μl was used to add the methylene blue platinum gold colloidal reagent to the water sample (20 μl each time).
(2) In order to avoid rupture of the anaerobic bottles during freezing, it is preferable to use a stepwise freezing method and the anaerobic bottles should be kept horizontally, according to the freeze-thaw method in ISO 24261-2 to eliminate ultra-fine bubbles in water. First, an anaerobic bottle containing the ultrafine bubble dispersion was horizontally placed in a refrigerator at 4℃for 12 hours. Next, the anaerobic bottles were transferred to a-20 ℃ refrigerator for more than 24 hours to ensure that all liquids became solid. Finally, the samples were thawed at room temperature. After the sample temperature stabilized, a specific volume of headspace gas was accurately withdrawn using a manual closed syringe needle (fig. 3). The number density of bubbles before and after freeze thawing was analyzed by a nanoparticle analyzer (NTA, nanoparticle Tracking Analysis) to examine the elimination efficiency.
(3) The extracted headspace gas was injected into the gas chromatograph for detection (fig. 4). The flow rate of argon (carrier gas) is controlled by a mass flow controller, and TCD (thermal conductivity detector) of the gas chromatograph is capable of converting the separated gas components into electrical signals and transmitting the electrical signals to a signal processing device (computer) to obtain peaks corresponding to the separated gas components and convert into the molar concentration of the gas.
Standard hydrogen gas may be purchased from natural gas companies or generated using hydrogen generators. The standard hydrogen content of the calibration gas was 0.5%,1%,5%,10%,20%,50% and 100% in this order. The experiment was performed using a closed-loop sample injection needle to accurately withdraw 0.2ml of headspace gas.
(4) In order to accurately measure the total amount of hydrogen in a dispersion of hydrogen UFB (Ultra Fine Bubble, ultra-fine bubbles, meaning bubbles having a particle diameter of 1 μm or less), it is necessary to establish a standard curve of the relationship between the hydrogen concentration and the hydrogen peak area in gas chromatography. Calibration curves were used for standard hydrogen at known percentages of 1%,5%,10%,20%, 40%, 60% and 80%. Both capillary columns and packed columns may be used. Because the capillary column has small injection volume, the change of the head space volume can be reduced and avoided, thereby reducing experimental errors. The calibration curve for hydrogen concentration is shown in fig. 5, so a nonlinear equation in the standard curve can be used to convert the peak area signal of hydrogen to percent hydrogen concentration.
And accurately calculating the volume of the solution in the anaerobic bottle by adopting a weighing method. The calculation formula of the total volume of the anaerobic bottle is as follows:
Figure BDA0004092638330000081
wherein M is a The mass of the anaerobic bottle containing a specific amount of ultrafine bubble dispersion liquid;
M b the quality of the anaerobic bottle;
ρ is the density of ultrapure water.
And accurately calculating the top air volume of the anaerobic bottle by adopting a weighing method. The calculation formula is as follows:
Figure BDA0004092638330000082
wherein V is total The total volume of the anaerobic bottle;
V water is the volume of the liquid sample;
M T the quality of the ultrapure water corresponding to the filling of the anaerobic bottle with the ultrapure water.
The percent hydrogen data from gas chromatography was converted to hydrogen concentration and the unit conversion equation from% to mol/m3 is shown below. Assuming that the gas is an ideal gas, the gas pressure (P) is 1atm.
Figure BDA0004092638330000083
Wherein C is i Is the concentration of the gas component (mol/m) 3 Or%);
n is the number of moles of gas (g/mol);
P 0 is standard atmospheric pressure (1 atm);
T 0 is at standard temperature (273.15K);
p is the gas pressure (atm) of the headspace of the anaerobic bottle;
v is the headspace volume (mL) of the anaerobic bottle;
r is a gas constant (R= 8.20544 ×10- 5 m 3 atm/mol K)；
T is the detection temperature (K).
According to the ideal gas equation pv=nrt, the total mole number (n) of the headspace hydrogen can be calculated by utilizing the headspace volume in the anaerobic bottle under certain pressure and temperature. And then the concentration of hydrogen in the water sample is calculated, and the calculation formula is as follows:
Figure BDA0004092638330000091
wherein, the liquid crystal display device comprises a liquid crystal display device,
Figure BDA0004092638330000092
is the molar mass of hydrogen (2.01588 g/mol)
Embodiment-relation of Hydrogen content with ultrafine bubble number concentration and dissolved Hydrogen
The results of hydrogen concentration measurements for 17 liquid samples containing different concentrations of ultrafine bubbles are shown in table 1. The freeze thawing method is effective for eliminating superfine bubbles and has a removal rate of over 99 percent.
TABLE 1 determination of Hydrogen content in different UFB dispersions by two methods
Figure BDA0004092638330000093
The analysis results of samples No. 1 to No. 12 in table 1 are one example of determining the hydrogen content in the hydrogen ultrafine bubble water by titration and gas chromatography. And mixing the hydrogen water and the hydrogen ultrafine bubble water according to different proportions to obtain hydrogen water samples with different bubble concentrations. The concentration and size distribution of the ultra-fine bubbles were analyzed by a nanoparticle analyzer. The measurement results of the content of dissolved hydrogen in different samples are similar to those of the oxidation titration method. When the concentration of the ultrafine bubbles is less than 2.0X10 7 At particle/mL, the titration (oxidation) assay results were close to the true value (samples 1 to 8). But when the bubble concentration is higher than 2.0X10 7 At individual/mL, the bubble itself can affect the accuracy of the measurement (sample number 9 to 12). The embodiment shows that the method for detecting the hydrogen concentration in the liquid containing the ultrafine bubbles based on the gas chromatography combined with the titration method can accurately and effectively detect the total hydrogen content in the water body. Meanwhile, the method is not limited by the properties of the sample, and has the characteristics of accuracy, effectiveness, simplicity in operation, easiness in implementation and the like.
What is not described in detail in the present specification belongs to the prior art known to those skilled in the art. It is noted that the above description is helpful for a person skilled in the art to understand the present invention, but does not limit the scope of the present invention. Any and all such equivalent substitutions, modifications and/or deletions as may be made without departing from the spirit and scope of the invention.

Claims (8)

1. The accurate determination method for the total hydrogen content in the water body containing the hydrogen ultrafine bubbles is characterized by comprising the following steps of:
step 1, sealing a water sample to be tested containing hydrogen ultrafine bubbles in an anaerobic bottle;
step 2, releasing hydrogen in ultra-fine bubbles in the water sample to the headspace in the anaerobic bottle by utilizing a freeze thawing technology;
step 3, measuring the content of the headspace hydrogen by using a gas chromatograph;
and 4, determining the total hydrogen content in the water sample according to the volume, the headspace volume, the air pressure and the temperature of the water sample in the anaerobic bottle.
2. The method for accurately determining the total hydrogen content in a water body containing hydrogen ultrafine bubbles according to claim 1, wherein the step 1 comprises: before sealing a water sample, taking a certain amount of water sample, and carrying out titration measurement on dissolved hydrogen of the water sample by using a methylene blue platinum colloidal reagent to estimate the content of the dissolved hydrogen; then the water sample to be detected containing hydrogen ultrafine bubbles is sealed in an anaerobic bottle through a butyl rubber plug, an aluminum cover and a bottle opener, and the volume of the water sample to be detected is less than or equal to 80% of the volume of the anaerobic bottle.
3. The method for accurately determining the total hydrogen content in a water body containing hydrogen ultrafine bubbles according to claim 1, wherein the freeze thawing technique in the step 2 comprises the following steps: step 2a, horizontally placing the anaerobic bottle in a refrigerator at 4 ℃ for 12 hours; step 2b, transferring the anaerobic bottle into a refrigerator at the temperature of minus 20 ℃ for more than or equal to 24 hours to ensure that the water sample to be tested changes phase and becomes solid ice; and 2c, thawing the solid ice water sample to be detected at room temperature to restore the solid ice water sample to be detected into a liquid water sample to be detected.
4. The method for accurately determining the total hydrogen content in a water body containing hydrogen ultrafine bubbles according to claim 1, wherein the step 3 comprises determining the headspace hydrogen content by using a capillary column or a packed column; the operation condition of the capillary column is that a) carrier gas is argon or helium, the constant flow mode is adopted, and the measuring flow of the outlet of the column is 12mL/min; b) The gas sample injection amount is 0.2mL; c) A chromatographic column, namely a molecular sieve with the model of Msieve5A, which has the length of 30m, the outer diameter of 0.53mm and the inner diameter of 50 mu m; d) Column temperature is 100 ℃; e) The TCD temperature of the thermal conductivity detector is 110 ℃; the operation conditions of the packed column are as follows, a) carrier gas is argon or helium, a constant flow mode is adopted, and the measuring flow rate of the outlet of the column is 30mL/min; b) The gas sample injection amount is 1ml; c) A chromatographic column, namely a molecular sieve with the model of Msieve5A, which has the length of 1.83m, the outer diameter of 3.1mm, the inner diameter of 2mm and the mesh size of 60-80 meshes; d) Column temperature 60 ℃.
5. The method for accurately determining the total hydrogen content in a hydrogen ultra-fine bubble-containing water body according to claim 1, wherein the water sample volume V in the step 4 water And a headspace volume V gas The calculation formula of (2) is as follows:
Figure FDA0004092638310000011
Figure FDA0004092638310000012
wherein Ma is the mass of an anaerobic bottle containing a water sample to be detected, mb is the mass of an empty anaerobic bottle, ρ is the density of ultrapure water, and V total Is the total volume of the anaerobic bottle, M T The quality of the ultrapure water corresponding to the filling of the anaerobic bottle with the ultrapure water.
6. The method for accurately measuring the total hydrogen content in a hydrogen ultra-fine bubble-containing water body according to claim 5, wherein the step 4 comprises converting the headspace hydrogen content obtained by a gas chromatograph from volume% to mol/m 3 The conversion formula is as follows:
Figure FDA0004092638310000021
wherein i is a gasComponent hydrogen; c (C) i Is the hydrogen concentration; c (C) i ， ％ Is the volume percentage concentration of hydrogen;
Figure FDA0004092638310000022
is the molar concentration of hydrogen mol/m 3 The method comprises the steps of carrying out a first treatment on the surface of the n is the mole number g/mol of the headspace gas; n is n i Is the mole number g/mol of hydrogen; p (P) 0 1atm at standard atmospheric pressure; t (T) 0 A standard temperature of 273.15K; p is headspace gas pressure atm; v is the headspace volume mL; r is a gas constant, r= 8.20544 ×10 - 5 m 3 atm/mol K; t is the headspace gas temperature K.
7. The method for accurately determining the total hydrogen content in a water body containing hydrogen ultrafine bubbles according to claim 6, wherein the step 4 comprises calculating the total hydrogen content in the water sample by adopting the following formula
Figure FDA0004092638310000023
Figure FDA0004092638310000024
Wherein the method comprises the steps of
Figure FDA0004092638310000025
Molar mass of hydrogen, +.>
Figure FDA0004092638310000026
8. The method according to claim 1, wherein the step 3 comprises establishing a calibration curve of the relationship between the hydrogen concentration and the hydrogen peak area in the gas chromatograph, wherein the calibration curve is used for standard hydrogen with known percentages of 1%,5%,10%,20%, 40%, 60% and 80%, and the peak area signal of the hydrogen is converted into the percentage concentration of the hydrogen by using a nonlinear equation in the standard curve.
CN202310154414.9A 2023-02-22 2023-02-22 Accurate determination method for total hydrogen content in water body containing hydrogen ultrafine bubbles Pending CN116338036A (en)

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