A method and system for in-situ detection of heavy water enrichment in electrolyzed water or electrolyzed seawater
Patent Information
- Application Number
- CN202611156470.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-07-31
- Publication Date
- 2026-11-03
AI Technical Summary
Existing technologies cannot achieve in-situ, real-time, non-contact, and highly sensitive detection of heavy water enrichment in electrolyzed water or electrolyzed seawater. Furthermore, conventional spectroscopic methods have low detection sensitivity in complex matrices, making it difficult to meet the needs of early enrichment monitoring.
A quantitative strategy combining Raman spectroscopy and/or infrared spectroscopy with peak area ratio was adopted. By establishing a standard curve of OD vibrational spectrum, the electrolyte thin-layer spectrum was acquired in real time, baseline correction and peak area ratio calculation were performed, and the heavy water enrichment efficiency was evaluated in combination with the cumulative charge of electrolysis.
It achieves real-time, non-contact, and highly sensitive monitoring of heavy water enrichment during electrolysis, with a detection limit of 0.5 at%. It can capture D2O enrichment signals at an early stage and maintain detection stability in complex matrices, making it suitable for various electrolyte systems.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of spectroscopic analysis and electrochemical detection technology, and in particular to a method and system for in-situ detection of heavy water enrichment in electrolyzed water or electrolyzed seawater. Background Technology
[0002] Heavy water (D2O) is an important substance in the nuclear industry, isotope labeling, and optical materials. Electrolysis of natural water (including freshwater and seawater) is one of the classic methods for enriching D2O: due to the hydrogen isotope kinetics (KIE), H2O molecules are more easily reduced to H2 at the electrode surface than D2O molecules, leading to a gradual increase in the D2O concentration in the remaining electrolyte. In the process of producing hydrogen from seawater, in-situ monitoring of D2O formation and enrichment is of great significance for understanding the isotope fractionation mechanism and optimizing the electrolysis process.
[0003] Traditional methods for D2O concentration detection include density methods, mass spectrometry, gas chromatography-mass spectrometry (GC-MS), and droplet methods. These methods typically require offline sampling and destructive analysis of samples, and the instruments are expensive and complex to operate, making in-situ, real-time, and non-contact monitoring during the electrolysis process impossible. Raman spectroscopy and infrared spectroscopy can both identify vibrational differences in OD groups, but existing technologies are mostly used for qualitative or semi-quantitative analysis of static samples. They lack in-situ detection solutions for the dynamic, multiphase (solid-liquid-gas), and high-salt environment of water / seawater electrolysis, and their detection sensitivity is generally low (typically only 1–5 at%), making it difficult to meet the needs of early enrichment monitoring. The following are some of the main detection methods: 1. Density Method: This method is based on the density difference between D₂O and H₂O. At 20℃, the density of pure H₂O is 0.9982 g / cm³. 3 The density of pure D2O is 1.1056 g / cm³. 3 In specific testing, the density of the sample is measured using a specific gravity bottle or digital densitometer under constant temperature conditions (usually controlled within ±0.1℃). The density is then compared with a pre-established density-D₂O concentration standard curve or conversion table to obtain the mole fraction of D₂O. This method has a detection accuracy of approximately 0.1–0.5 at%, but requires several milliliters of sample and must be performed offline.
[0004] 2. Refractive Index Method: This method utilizes the difference in refractive index between D₂O and H₂O. At 20℃ and under sodium D-line (589 nm) conditions, the refractive index of H₂O is 1.3330, while that of D₂O is 1.3284, meaning the refractive index of D₂O is slightly lower than that of H₂O. In practice, the sample is dropped onto the measuring prism of an Abbe refractometer or digital refractometer, the refractive index value is read, and the D₂O content is calculated based on a pre-calibrated refractive index-D₂O concentration curve. This method requires a small sample volume (only a few drops) and is rapid, but due to the small difference in refractive index, the detection accuracy is approximately 0.5–1 at%, and it is easily affected by temperature and impurities, making it an offline detection method.
[0005] 3. Falling Drop Method: This method calculates the density of D2O by measuring the settling velocity of a droplet in an immiscible liquid, thus determining the D2O concentration. In practice, a droplet (approximately 0.01–0.05 mL) of the D2O-H2O mixture to be tested is carefully injected into a vertically graduated tube containing chlorobenzene, o-dichlorobenzene, or other organic solvent. The droplet, being denser than the organic solvent, slowly sinks. The time required for the droplet to settle a fixed distance (e.g., 20 cm) is recorded; the settling time is inversely proportional to the droplet density. A settling time-concentration standard curve is plotted using a standard solution with a known D2O concentration. By comparing the curve, the D2O concentration of the sample can be determined. This method achieves an accuracy of 0.1 at%, but requires the use of toxic organic solvents, is cumbersome, and must be performed offline.
[0006] 4. Nuclear Magnetic Resonance (NMR): This method utilizes deuterium nuclei (… 2 D) No production 1 Quantification is performed based on H signals and differences in chemical shifts. There are two specific methods: one is... 1 1H NMR method for collecting water samples to be tested 1 In the H-ray spectroscopy, the integrated peak intensity of protons in water molecules is directly proportional to the H2O content and inversely proportional to the D2O content. The D2O concentration can be calculated by comparing it with standard samples of known concentrations. 2 DNMR directly detects the resonance signal of deuterium nuclei, and the signal intensity is directly proportional to the D2O concentration. During measurement, the water sample must be transferred to an NMR sample tube and placed inside a high-field NMR spectrometer. NMR can achieve a detection accuracy better than 0.1 at%, but the instruments are expensive, samples must be collected offline, and in-situ continuous monitoring is not possible.
[0007] 5. Gas Chromatography-Mass Spectrometry (GC-MS): This method first converts hydrogen isotopes in the water sample into hydrogen molecules, which are then detected by mass spectrometry. The specific steps are as follows: A trace amount of water sample (usually 1–10 μL) is placed in a reaction tube and reacted with a metal reducing agent (such as uranium, zinc, chromium, or manganese) at a high temperature (approximately 500–800 °C). The water is reduced to hydrogen gas (including H2, HD, and D2). The resulting gas mixture is separated by a gas chromatograph and then enters the mass spectrometer detector. Selective ion monitoring is performed at m / z 2 (H2), 3 (HD), and 4 (D2). The D / H isotope ratio is calculated based on the abundance ratio of each ion current, and then converted to the D2O mole fraction. The detection limit of this method can be as low as 0.01 at%, but it requires complex sample pretreatment, is a destructive, offline detection method, and has a long analysis time (several minutes to tens of minutes).
[0008] 6. Infrared Isotope Mass Spectrometry (IRMS): This method is currently the benchmark for measuring hydrogen isotope ratios. In practice, a water sample reacts with a reducing agent at high temperature to generate hydrogen gas, which then enters a high-resolution magnetic fan mass spectrometer. The instrument simultaneously detects the ion currents at m / z 2 (H2) and m / z 3 (HD) using a Faraday cup, or compares the isotope ratios between the unknown sample and a standard gas using a dual-injection system. IRMS can measure the D / H ratio with an accuracy of ±0.5‰ (corresponding to an accuracy of approximately 0.001 at% for D2O concentration). However, this method requires extremely expensive equipment and demanding sample preparation, making it completely unsuitable for in-situ real-time monitoring during electrolysis.
[0009] 7. Conductivity method: This method is based on H... + and OH - The slight difference in migration rates between H₂O and D₂O (called the isotope effect). Theoretically, H₂O in pure water... + The migration rate in H2O is approximately 1.2 times that in D2O, OH - Similar discrepancies exist. In specific testing, a high-precision conductivity meter is used to measure the conductivity of deionized water samples, and the D2O content is calculated using a standard curve. However, this method only shows a weak response under conditions of extreme purity and the absence of background electrolytes. In actual water or seawater electrolysis systems, the electrolyte contains a large number of ions (such as Na+). + Cl - K + OH - (etc.), the background conductivity is much higher than the small changes caused by the isotope effect, therefore the conductivity method is not suitable for the detection of heavy water in electrolytes.
[0010] 8. Ultrasonic Velocity Method: This method utilizes the difference in sound wave propagation speed between D₂O and H₂O. At 20°C, the speed of sound is approximately 1482 m / s in H₂O and approximately 1408 m / s in D₂O. In practice, ultrasonic transmitting and receiving probes are placed on opposite sides or the same side of the liquid being tested. The transit time of the sound wave over a fixed distance is measured, the speed of sound is calculated, and the D₂O concentration is obtained from the sound speed-D₂O concentration standard curve. The speed of sound is extremely sensitive to temperature (the rate of change is approximately 2–3 m / s·°C). -1 Furthermore, the large number of bubbles generated during electrolysis severely scatters and absorbs ultrasonic waves, leading to measurement failure. Therefore, this method is not suitable for in-situ detection of water / seawater electrolysis systems. Summary of the Invention
[0011] The purpose of this invention is to overcome the technical problems existing in the prior art and provide a method and system for in-situ detection of heavy water enrichment in electrolyzed water or electrolyzed seawater. It aims to utilize the specific response of Raman spectroscopy and / or infrared spectroscopy to OD stretching vibration, combined with a peak area ratio quantitative strategy, to achieve real-time, non-contact, and highly sensitive monitoring of D2O concentration during electrolysis, with a detection limit of 0.5 at%. It also effectively overcomes the interference of bubbles generated during electrolysis, fluctuations in excitation light power, and the complex matrix of seawater on the spectral signal.
[0012] The objective of this invention is achieved through the following technical solution: A first aspect of the present invention provides a method for in-situ detection of heavy water enrichment in electrolyzed water or electrolyzed seawater, comprising the following steps: S1. Establish the standard curve of OD vibration spectrum: Prepare a series of standard solutions with known heavy water mole fraction, collect the Raman spectrum and / or infrared spectrum of each standard solution, calculate the peak area ratio of the OD stretching vibration peak corresponding to the Raman spectrum and / or calculate the peak area ratio of the OD characteristic absorption peak corresponding to the infrared spectrum, and fit the standard curve equation between the peak area ratio and the heavy water mole fraction. S2. In-situ spectral acquisition: The electrolytic cell is placed in the optical path of a Raman spectrometer or an infrared spectrometer, and the excitation light or infrared light is focused onto the thin layer of electrolyte on the surface of the working electrode through the optical window. While electrolysis is in progress, the Raman spectrum and / or infrared spectrum of the thin layer of electrolyte are acquired in real time at set time intervals. S3. Ratio Calculation: Baseline correction is performed on the in-situ spectral data collected in step S2, and the peak area ratio of the OD stretching vibration peak and / or the peak area ratio of the OD characteristic absorption peak are calculated. S4. Concentration Inversion: Substitute the peak area ratio calculated in step S3 into the standard curve equation in step S1 to calculate the mole fraction of heavy water in the electrolyte at the current moment. S5. Enrichment Dynamic Monitoring: Based on the mole fraction calculated in step S4, determine whether heavy water enrichment has occurred based on the preset heavy water concentration detection limit, and output an early warning signal or automatically record the enrichment time point when heavy water enrichment occurs.
[0013] In some embodiments, the acquisition of the infrared spectrum includes: Using the attenuated total internal reflection mode, with a silicon prism as the ATR crystal, infrared light is incident from one side of the silicon prism and undergoes total internal reflection at the interface between the prism and the electrolyte. The resulting evanescent wave penetrates into the electrolyte thin layer. The reflected light signal is collected, and the characteristic absorption peak of OD at 2100 cm⁻¹ is analyzed. -1 ~2800 cm -1 The absorption intensity ratio, with a spectral resolution of 4 cm⁻¹ -1 The number of scans was 32.
[0014] In some embodiments, the acquisition of the Raman spectrum includes: The excitation wavelength is 532 nm, 633 nm or 785 nm, the acquisition adopts confocal mode, the laser power is 25mW, the light intensity is 50%, the integration time is 1 to 30 seconds, and the accumulation is 2 to 5 times.
[0015] In some embodiments, the standard solution in step S1 includes standard solutions with heavy water molar fractions of 0 at%, 0.2 at%, 0.5 at%, 1 at%, 2 at%, 5 at%, 10 at%, and 20 at%. The background electrolyte composition of the standard solution is consistent with that of the actual electrolyte. The standard curve equation is obtained by linear or quadratic function fitting, and it is verified that the spectral signal-to-noise ratio is ≥3 at a concentration of 0.5 at%.
[0016] In some embodiments, the optical window material of the electrolytic cell is selected from quartz, sapphire, or calcium fluoride; the working electrode is a hydrogen evolution electrode, selected from Pt, Ni, stainless steel, Ni-Mo alloy, or transition metal phosphides; and the electrolyte layer thickness is ≤200 μm.
[0017] In some embodiments, the method further includes real-time background subtraction of the in-situ spectrum acquired in step S3, wherein the background subtraction includes subtracting the scattering background of the bubbles generated by electrolysis and the fluorescence background of the seawater matrix; and Lorentz or Gauss-Lorentz mixed function fitting is performed on the OD stretching vibration peak or OD characteristic absorption.
[0018] In some embodiments, the electrolyte temperature is controlled to remain constant at a certain temperature value within the range of 15 to 35°C during the electrolysis process, with fluctuations within ±0.5°C.
[0019] In some embodiments, the electrolyte used for electrolyzing water or seawater includes fresh water, natural seawater, artificial seawater, alkaline aqueous solution, or high-salinity wastewater.
[0020] In some embodiments, the concentration detection limit is 0.5 at% heavy water mole fraction; step S5 further includes: The hydrogen isotope separation factor was calculated by combining the cumulative amount of electricity generated during electrolysis, which was used to evaluate the impact of different electrode materials and electrolysis conditions on the enrichment efficiency of heavy water.
[0021] A second aspect of the present invention provides a system for in-situ detection of heavy water enrichment in electrolyzed water or electrolyzed seawater, comprising: The standard curve construction module is used to prepare a series of standard solutions with known heavy water mole fractions, collect the Raman spectrum and / or infrared spectrum of each standard solution, calculate the peak area ratio of the OD stretching vibration peaks corresponding to the Raman spectrum and / or calculate the peak area ratio of the OD characteristic absorption peaks corresponding to the infrared spectrum, and fit the standard curve equation between the peak area ratio and the heavy water mole fraction. The in-situ spectral acquisition module is used to place the electrolytic cell in the optical path of a Raman spectrometer or an infrared spectrometer, so that the excitation light or infrared light is focused on the electrolyte thin layer on the surface of the working electrode through the optical window. While electrolysis is in progress, the Raman spectrum and / or infrared spectrum of the electrolyte thin layer are acquired in real time at set time intervals. The ratio calculation module is used to perform baseline correction on the acquired in-situ spectral data and to calculate the peak area ratio of the OD stretching vibration peak and / or the peak area ratio of the OD characteristic absorption peak. The concentration inversion module is used to substitute the calculated peak area ratio into the standard curve equation to calculate the mole fraction of heavy water in the electrolyte at the current moment. The enrichment dynamic monitoring module is used to determine whether heavy water enrichment has occurred based on the calculated mole fraction and the preset heavy water concentration detection limit, and to output an early warning signal or automatically record the enrichment time point when heavy water enrichment occurs.
[0022] It should be further noted that the technical features corresponding to the above-mentioned options and embodiments can be combined or substituted with each other to form new technical solutions without conflict.
[0023] Compared with the prior art, the beneficial effects of the present invention are: 1. In-situ real-time monitoring: By directly coupling the electrolytic cell to the optical path of the spectrometer and focusing the optical window on the thin layer on the electrode surface, dynamic change information of D2O concentration near the electrode interface can be obtained directly without sampling, labeling, or disrupting the electrolysis process, overcoming the shortcomings of traditional methods such as offline sampling and response lag.
[0024] 2. Detection limit as low as 0.5 at%: By optimizing spectral acquisition parameters (long integration time, multiple accumulations), adopting peak area ratio quantification and multi-peak fitting strategies, the detection sensitivity is significantly better than conventional spectroscopic methods (1–5 at%), and D2O enrichment signals can be captured at an early stage.
[0025] 3. Strong anti-interference ability: Using OD peak area as a quantitative basis, it effectively offsets interferences such as optical path attenuation, excitation light power fluctuations, electrolysis bubble scattering, and window contamination; high concentrations of Cl in seawater - Mg 2+ SO4 2- Plasma has minimal effect on the position and ratio of the OD vibration peaks, demonstrating the applicability of this method in complex matrices.
[0026] 4. Dual-spectral cross-verification: Raman spectroscopy is sensitive to the hydrogen bond structure of water, while infrared spectroscopy is sensitive to changes in dipole moment. Using the two together can cross-verify the results and improve the reliability of detection.
[0027] 5. Good versatility: Applicable to various electrolyte systems such as fresh water, seawater, and alkaline water, without changing the main steps, providing an effective online monitoring method for optimizing heavy water preparation processes and isotope fractionation research in the process of producing hydrogen from seawater by electrolysis.
[0028] 6. By controlling the electrolyte temperature within 15-35℃ ± 0.5℃, temperature-dependent drift of the OD stretching vibration peak position and width is avoided, ensuring the stability of the spectral ratio. Real-time subtraction of background from electrolytic bubble scattering and seawater fluorescence eliminates dynamic interference; Lorentz or Gaussian-Lorentz mixed function fitting improves peak area integration accuracy, ensuring quantitative accuracy. A thin layer thickness ≤ 200μm greatly reduces light attenuation in the solution, ensuring the signal primarily originates from the heavy water enrichment layer near the electrode interface.
[0029] 7. The hydrogen isotope separation factor can be calculated by combining the cumulative amount of electricity generated during electrolysis. This factor can be directly used to evaluate the impact of different electrode materials and electrolysis conditions on the enrichment efficiency of heavy water, providing a quantitative tool for process optimization. Attached Figure Description
[0030] Figure 1 This is a flowchart illustrating an in-situ detection method for heavy water enrichment in electrolyzed water or electrolyzed seawater, as shown in an embodiment of the present invention. Figure 2 This is a schematic diagram of the Raman detection method shown in the embodiments of the present invention, and Raman spectra of D2O at different concentrations; Figure 3 The integral area and standard curve of the OD bond in the Raman D2O spectrum shown in the embodiments of the present invention; Figure 4 This is a schematic diagram of the infrared detection method shown in the embodiments of the present invention, and infrared spectra of D2O at different concentrations; Figure 5 The integral area and standard curve of the OD bond in the infrared D2O spectrum shown in the embodiment of the present invention. Detailed Implementation
[0031] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0032] It should be noted that the defects in the solutions in the prior art are all the results of the inventors' practice and careful research. Therefore, the discovery process of the above problems and the solutions proposed by the embodiments of this application in the following text should be the inventors' contributions to this application in the process of invention and creation, and should not be understood as technical content known to those skilled in the art.
[0033] In view of the technical problems pointed out in the background art, the present invention provides the following embodiments: Example 1 In one exemplary embodiment, a method for in-situ detection of heavy water enrichment in electrolyzed water or electrolyzed seawater is provided, such as... Figure 1 As shown, it includes the following steps: S1. Establish the standard curve of OD vibration spectrum: Prepare a series of standard solutions with known heavy water mole fraction, collect the Raman spectrum and / or infrared spectrum of each standard solution, calculate the peak area ratio of the OD stretching vibration peak corresponding to the Raman spectrum and / or calculate the peak area ratio of the OD characteristic absorption peak corresponding to the infrared spectrum, and fit the standard curve equation between the peak area ratio and the heavy water mole fraction. S2. In-situ spectral acquisition: The electrolytic cell is placed in the optical path of a Raman spectrometer or an infrared spectrometer, and the excitation light or infrared light is focused onto the thin layer of electrolyte on the surface of the working electrode through the optical window. While electrolysis is in progress, the Raman spectrum and / or infrared spectrum of the thin layer of electrolyte are acquired in real time at set time intervals. S3. Ratio Calculation: Baseline correction is performed on the in-situ spectral data collected in step S2, and the peak area ratio of the OD stretching vibration peak and / or the peak area ratio of the OD characteristic absorption peak are calculated. S4. Concentration Inversion: Substitute the peak area ratio calculated in step S3 into the standard curve equation in step S1 to calculate the mole fraction of heavy water in the electrolyte at the current moment. S5. Enrichment Dynamic Monitoring: Based on the mole fraction calculated in step S4, determine whether heavy water enrichment has occurred based on the preset heavy water concentration detection limit, and output an early warning signal or automatically record the enrichment time point when heavy water enrichment occurs.
[0034] Specifically, in step S1, a series of H2O-D2O mixed standard solutions with known D2O molar fractions are prepared. The D2O molar fractions include at least 0 at%, 0.2 at%, 0.5 at%, 1 at%, 2 at%, 5 at%, 10 at%, and 20 at%. The background electrolyte composition of the standard solutions is consistent with the actual electrolyte system (e.g., 0.5 M NaCl to simulate seawater, or 0.1 M KOH to simulate alkaline water electrolysis conditions). The Raman spectroscopy acquisition range is 2100–2800 cm⁻¹. -1 Pay special attention to the OD stretching vibration peak (characteristic wavenumber 2100–2800 cm⁻¹). -1 The infrared spectral acquisition range is also 2100–2800 cm⁻¹. -1 Focus on the characteristic absorption peaks of OD. Perform baseline correction and peak fitting on the obtained spectra (using Lorentz or Gauss-Lorentz mixture functions), calculate the integral area of the OD peak, and fit the standard curve equation (linear or quadratic function) with the mole fraction of D2O (CD2O) as the independent variable and the integral area of OD. Verify that the spectral signal-to-noise ratio is ≥3 at a concentration of 0.5 at%.
[0035] In step S2, an in-situ spectroscopic-electrochemical measurement environment is constructed, and the acquisition of the infrared spectrum includes: Employing attenuated total internal reflection (AIR) mode, a silicon prism is used as the ATR crystal, directly contacting the electrolyte to enhance the interface signal. Infrared light is incident from one side of the silicon prism and undergoes total internal reflection at the interface between the prism and the electrolyte. The resulting evanescent wave penetrates into the thin electrolyte layer, with a penetration depth of [insert depth here]. d p The OD groups in the electrolyte exhibit characteristic absorption of infrared light at specific wavenumbers. The reflected light (IR), carrying absorption information, exits from the other side of the prism and is received by the detector. Analysis of the OD peak (2100–2900 cm⁻¹) reveals this characteristic absorption. -1 The absorption intensity ratio, with a resolution of 4 cm⁻¹ -1 The concentration of heavy water in the electrolyte can be calculated by scanning 32 times.
[0036] The acquisition of the Raman spectrum includes: The excitation wavelength is 532 nm, 633 nm or 785 nm, the acquisition adopts confocal mode, the laser power is 25mW, the light intensity is 50%, the integration time is 1 to 30 seconds, and the accumulation is 2 to 5 times.
[0037] Specifically, an electrolyte (freshwater or seawater) with a known initial D2O concentration (natural abundance, approximately 0.015 at%) is added to the electrolytic cell, and electrolysis is initiated using a constant current or constant voltage mode. Simultaneously, in-situ Raman and / or infrared spectra of the electrolyte near the electrode interface are acquired at fixed time intervals (30 seconds, 1 minute, or 5 minutes), and the intensity or integrated area of the OD peak is recorded in real time.
[0038] The optical window material of the electrolytic cell is selected from quartz, sapphire, or calcium fluoride; the working electrode is a hydrogen evolution electrode, selected from Pt, Ni, stainless steel, Ni-Mo alloy, or transition metal phosphides; and the electrolyte layer thickness is ≤200 μm.
[0039] Preferably, the in-situ spectrum acquired in step S3 undergoes real-time background subtraction, which includes subtracting the scattering background from bubbles generated during electrolysis and the fluorescence background from the seawater matrix; and the OD stretching vibration peak or OD characteristic absorption is fitted with a Lorentz or Gaussian-Lorentz mixed function. During electrolysis, the electrolyte temperature is controlled to be constant within a certain temperature range of 15–35℃, with fluctuations within ±0.5℃.
[0040] Furthermore, the real-time acquired spectral data is substituted into the standard curve equation established in step one to calculate the mole fraction of D2O in the electrolyte at the current moment. When the calculated D2O concentration reaches or exceeds 0.5 at%, an early warning signal is output or the enrichment time point is automatically recorded. The hydrogen isotope separation factor is calculated in conjunction with the cumulative electrolysis charge to evaluate the impact of different electrode materials and electrolysis conditions on the heavy water enrichment efficiency.
[0041] Example 2 Based on the inventive concept of Example 1, this example achieves in-situ detection of D2O enrichment in electrolyzed alkaline water. Specifically, it includes: Electrolyte: 1.0 M KOH aqueous solution, with initial D2O at natural abundance (approximately 0.015 at%).
[0042] Instrument: Confocal Raman spectrometer (excitation wavelength 532 nm, power 50 mW, grating 600 gr / mm, integration time 10 seconds, 3 accumulations).
[0043] Electrolytic cell: Self-made optical window electrolytic cell (the window is a quartz plate, the working electrode is a Pt plate, the counter electrode is a Pt wire, and the electrode spacing is 2 mm).
[0044] step: Prepare 0.1 M KOH standard solutions with D2O mole fractions of 0%, 0.2%, 0.5%, 1%, 2%, 5%, 10%, and 20%, and collect Raman spectra (e.g., Figure 2 (As shown). Calculate the OD peak (approximately 2100 cm⁻¹).-1 ~2800 cm -1 (Integral area).
[0045] Fitting the standard curve: In 0.5 at% standard solution, the signal-to-noise ratio of the OD peak is 4.2, which meets the detection limit requirement.
[0046] Electrolysis experiment: at -200 mA / cm -2 Electrolysis was performed at a constant current density, and Raman spectra were collected every 60 seconds.
[0047] Results: After 180 minutes of electrolysis, the value increased from the initial 0.015 at% to 0.8 at%; after 240 minutes of electrolysis, the corresponding concentration was 1.0 at%. Even though a large number of H2 bubbles were generated during electrolysis and the spectrum showed short-term fluctuations, the ratio remained stable, proving that the method has strong anti-interference ability.
[0048] Example 3 Based on the inventive concept of Example 1, this example achieves in-situ detection of D2O enrichment in simulated seawater via electrolysis. Compared with Example 2, it also uses Raman spectroscopy, but the difference lies in the use of different electrode materials, specifically including: Electrolyte: Artificial seawater (salinity 35‰, formula: NaCl 24.5 g / L, MgCl2·6H2O 11.1 g / L, Na2SO4 4.1 g / L, CaCl2 1.2 g / L, KCl 0.7 g / L, NaHCO3 0.2 g / L), initial D2O at natural abundance (approximately 0.015 at%).
[0049] Instrument: Confocal Raman spectrometer (excitation wavelength 633 nm, power 40 mW, grating 600 gr / mm, integration time 15 seconds, 4 accumulations).
[0050] Electrolytic cell: Optical window electrolytic cell (window is sapphire), working electrode is Ni-Mo alloy electrode (high hydrogen evolution activity), counter electrode is Pt sheet, reference electrode is Ag / AgCl (saturated KCl), electrode spacing is 3 mm.
[0051] step: Standard solutions with D2O molar fractions of 0%, 0.2%, 0.5%, 1%, 2%, 5%, 10%, and 20% were prepared using the same artificial seawater, and Raman spectra were acquired. Fluorescence background subtraction was performed on the spectra (residual organic matter in the artificial seawater may produce weak fluorescence), and the OD peak (2100 cm⁻¹) was calculated. -1 ~2500 cm -1 The peak area of the standard curve is: Area = 25132 + 391692CD2O, R. 2 = 0.999 (e.g.) Figure 3 (As shown). In 0.5 at% standard solution, the signal-to-noise ratio of the OD peak after background subtraction is 4.0.
[0052] At −100 mA / cm -2 Electrolysis was performed under constant current density, and Raman spectra were collected every 90 seconds while monitoring changes in electrode potential.
[0053] Results: After 240 minutes of electrolysis, the mole fraction of D2O increased from the initial 0.015 at% to 0.6%; after 200 minutes of electrolysis, the concentration reached 1.0 at%. This was despite the presence of various ions and trace amounts of fluorescent substances in the artificial seawater. Compared to Example 2 (Ni foam electrode), the Ni-Mo alloy electrode exhibited a lower hydrogen evolution overpotential, higher electrolysis efficiency, and a longer time required to achieve 0.5 at% heavy water enrichment (200 minutes vs. 300 minutes), which may be related to differences in isotopic fractionation factors on the electrode surface. This further demonstrates that this method can be used to compare the enrichment performance of different electrode materials.
[0054] Example 4 Based on the inventive concept of Example 1, this example achieves in-situ detection of D2O enrichment in electrolyzed natural seawater. Specifically, it includes: Electrolyte: Natural seawater from Bohai Bay (filtered through a 0.45 μm membrane, with no other electrolytes added), with initial D2O at natural abundance.
[0055] Instrument: Attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), with an internal reflection element of ZnSe, and a resolution of 4 cm⁻¹. -1 , scanned 32 times.
[0056] Electrolytic cell: A specially designed electrolytic cell is pressed above the silicon prism crystal of ATR. The working electrode is Ni foam and the counter electrode is Pt sheet.
[0057] step: Standard solutions with different D2O concentrations were prepared using artificial seawater (35‰ salinity). ATR-FTIR spectra were collected, and the OD absorption peak (2100 cm⁻¹) was calculated. -1 ~2500 cm -1 The integral area, the standard curve equation is, and the linear range is 0–20 at%. At -200 mA / cm² -2 Electrolysis was performed under constant current, and the spectrum was collected every 120 seconds. Infrared spectra of D2O at different concentrations are shown below. Figure 4 As shown.
[0058] Result: Although Cl exists in seawater - Mg 2+The OD peak position did not shift significantly after background subtraction, and it remained clearly identifiable even after background removal, containing organic matter. After 500 minutes of electrolysis, the D2O concentration was calculated to be 2 at%, further validating the applicability of this method in complex matrices and the reliability of the 0.5 at% detection limit.
[0059] Example 5 Based on the inventive concept of Example 1, this example achieves in-situ detection (infrared transmission mode) of D2O enrichment in electrolyzed fresh water. Specifically, it includes: Electrolyte: Deionized water (resistivity 18.2 MΩ·cm), initial D2O at natural abundance (approximately 0.015 at%), with no added electrolytes.
[0060] Instrument: Fourier transform infrared spectrometer (FTIR), equipped with a transmission liquid cell, optical path length of 10 μm, resolution of 4 cm⁻¹ -1 32 scans, spectral range 2100 cm⁻¹ -1 ~2800 cm -1 .
[0061] step: Deionized water standard solutions with D₂O molar fractions of 0%, 0.2%, 0.5%, 1%, 2%, 5%, 10%, and 20% were prepared. Transmission infrared spectra of each solution were acquired using a CaF₂ liquid cell with a 10 μm optical path. Baseline correction was performed on the acquired spectra, and the OD absorption peak (2100 cm⁻¹) was calculated. -1 ~2800 cm -1 The peak area of the curve is calculated. The fitted standard curve equation is: Area = 0.04 + 0.88 C D2O, R 2 = 0.999 (e.g.) Figure 5 (As shown). In 0.5 at% standard solution, the absorbance signal-to-noise ratio of the OD peak is 3.5, which meets the detection limit requirement.
[0062] Electrolyte was injected into a micro transmission electrolytic cell and electrolyzed in constant voltage mode (−2.0 V vs. ITO counter electrode). Infrared spectra were collected every 30 seconds, and current changes were recorded simultaneously.
[0063] Results: After 90 minutes of electrolysis, the mole fraction of D2O increased from the initial 0.015 at% to 0.5%; after 240 minutes of electrolysis, the corresponding concentration was 1.0 at%, successfully detecting the enrichment of heavy water. Due to the extremely short optical path of the electrolytic cell and the small electrode spacing, the generated H2 bubbles can escape rapidly, causing minimal interference to the spectrum, thus verifying the feasibility of the infrared transmission mode in pure water systems and the detection limit of 0.5 at%.
[0064] Example 6 Based on the inventive concept of Example 1, this example achieves continuous monitoring and separation factor calculation during long-term electrolysis. Specifically, it includes: Electrolyte: 0.5 M NaCl aqueous solution (simulating high-salt wastewater), with initial D2O at natural abundance (approximately 0.015 at%).
[0065] Instrument: Confocal Raman spectrometer (excitation wavelength 785 nm, power 80 mW, grating 1200 gr / mm, integration time 20 seconds, 5 accumulations, using 785 nm to reduce fluorescence interference).
[0066] Electrolytic cell: Flow-through optical window electrolytic cell (quartz window), working electrode is stainless steel mesh (316L, 100 mesh), counter electrode is titanium mesh, electrode spacing is 5 mm. The electrolyte is continuously circulated by a peristaltic pump at a flow rate of 0.5 mL / min to maintain solution homogeneity and remove generated gases.
[0067] Separation factor: In electrolysis, the separation factor is usually defined as the ratio of hydrogen isotopes in the liquid (water) and gas (hydrogen). For deuterium (D) and hydrogen (H), the most common definition is: α = (D / H)liquid / (D / H)gas (D / H) liquid: indicates the ratio of the number of deuterium atoms to the concentration of hydrogen atoms in the remaining water.
[0068] (D / H) gas: This indicates the ratio of the number of deuterium atoms to the concentration of hydrogen atoms in the produced hydrogen gas.
[0069] This definition intuitively reflects the separation effect: α > 1 means that during electrolysis, hydrogen (H) is more easily reduced to hydrogen gas at the cathode and escapes, while the heavy isotope deuterium (D) is more enriched in the remaining liquid water.
[0070] step: D₂O standard solutions (0, 0.2%, 0.5%, 1%, 2%, 5%, 10%, 20%) were prepared using 0.5 M NaCl solution, and Raman spectra were collected. Standard curve: Area = 25000 + 210000CD₂O, R 2 = 0.999, R 2 = 0.998. The signal-to-noise ratio of the OD peak in the 0.5 at% standard solution is 4.5.
[0071] At a constant current of −200 mA / cm -2 The system was continuously electrolyzed for 12 hours, with Raman spectra automatically acquired every 5 minutes, and the cumulative charge was recorded. During each acquisition, the peristaltic pump was paused for 10 seconds to minimize the impact of flow on the spectrum.
[0072] Results: After 3 hours of electrolysis, the D2O concentration was approximately 0.33 at%; after 6 hours (0.432 Ah), the concentration was 0.55 at%; after 8 hours, the concentration was 1.5 at%; and after a final 12 hours of electrolysis, the concentration was 2 at%. Throughout the process, even under long-term operation, the spectral baseline remained stable, demonstrating that this method is suitable for long-term continuous monitoring.
[0073] The above embodiments cover different electrolytes (alkaline water, fresh water, artificial seawater, high-salinity wastewater), different spectroscopic techniques (Raman confocalization, ATR-FTIR), different electrode materials (Pt, Ni foam, Ni-Mo alloy, stainless steel mesh), and different time scales (short time, long time), comprehensively verifying the in-situ detection capability and anti-interference performance of the method of the present invention at the detection limit of 0.5 at%.
[0074] The above detailed embodiments are a description of the present invention. It should not be considered that the specific embodiments of the present invention are limited to these descriptions. For those skilled in the art, several simple deductions and substitutions can be made without departing from the concept of the present invention, and all of these should be considered to fall within the protection scope of the present invention.
Claims
1. A method for in-situ detection of heavy water enrichment in electrolyzed water or electrolyzed seawater, characterized in that, Includes the following steps: S1. Establish the standard curve of OD vibration spectrum: Prepare a series of standard solutions with known heavy water mole fraction, collect the Raman spectrum and / or infrared spectrum of each standard solution, calculate the peak area ratio of the OD stretching vibration peak corresponding to the Raman spectrum and / or calculate the peak area ratio of the OD characteristic absorption peak corresponding to the infrared spectrum, and fit the standard curve equation between the peak area ratio and the heavy water mole fraction. S2. In-situ spectral acquisition: The electrolytic cell is placed in the optical path of a Raman spectrometer or an infrared spectrometer, and the excitation light or infrared light is focused onto the thin layer of electrolyte on the surface of the working electrode through the optical window. While electrolysis is in progress, the Raman spectrum and / or infrared spectrum of the thin layer of electrolyte are acquired in real time at set time intervals. S3. Ratio Calculation: Baseline correction is performed on the in-situ spectral data collected in step S2, and the peak area ratio of the OD stretching vibration peak and / or the peak area ratio of the OD characteristic absorption peak are calculated. S4. Concentration Inversion: Substitute the peak area ratio calculated in step S3 into the standard curve equation in step S1 to calculate the mole fraction of heavy water in the electrolyte at the current moment. S5. Enrichment Dynamic Monitoring: Based on the mole fraction calculated in step S4, determine whether heavy water enrichment has occurred based on the preset heavy water concentration detection limit, and output an early warning signal or automatically record the enrichment time point when heavy water enrichment occurs.
2. The method for in-situ detection of heavy water enrichment in electrolyzed water or electrolyzed seawater according to claim 1, characterized in that, The acquisition of the infrared spectrum includes: Using the attenuated total internal reflection mode, with a silicon prism as the ATR crystal, infrared light is incident from one side of the silicon prism and undergoes total internal reflection at the interface between the prism and the electrolyte. The resulting evanescent wave penetrates into the electrolyte thin layer. The reflected light signal is collected, and the characteristic absorption peak of OD at 2100 cm⁻¹ is analyzed. -1 ~2800 cm -1 The absorption intensity ratio, with a spectral resolution of 4 cm⁻¹ -1 The number of scans was 32.
3. The method for in-situ detection of heavy water enrichment in electrolyzed water or electrolyzed seawater according to claim 1, characterized in that, The acquisition of the Raman spectrum includes: The excitation wavelength is 532 nm, 633 nm or 785 nm, the acquisition adopts confocal mode, the laser power is 25mW, the light intensity is 50%, the integration time is 1 to 30 seconds, and the accumulation is 2 to 5 times.
4. The method for in-situ detection of heavy water enrichment in electrolyzed water or electrolyzed seawater according to claim 1, characterized in that, The standard solutions mentioned in step S1 include standard solutions with heavy water molar fractions of 0 at%, 0.2 at%, 0.5 at%, 1 at%, 2 at%, 5 at%, 10 at%, and 20 at%. The background electrolyte composition of the standard solutions is consistent with that of the actual electrolyte. The standard curve equation is obtained by linear or quadratic function fitting, and it is verified that the spectral signal-to-noise ratio is ≥3 at a concentration of 0.5 at%.
5. The method for in-situ Raman detection of heavy water enrichment in electrolyzed water or electrolyzed seawater according to claim 1, characterized in that, The optical window material of the electrolytic cell is selected from quartz, sapphire or calcium fluoride; the working electrode is a hydrogen evolution electrode, selected from Pt, Ni, stainless steel, Ni-Mo alloy or transition metal phosphides; the electrolyte layer thickness is ≤200 μm.
6. The method for in-situ detection of heavy water enrichment in electrolyzed water or electrolyzed seawater according to claim 1, characterized in that, It also includes real-time background subtraction of the in-situ spectrum collected in step S3, wherein the background subtraction includes subtracting the scattering background of the bubbles generated by electrolysis and the fluorescence background of the seawater matrix; and Lorentz or Gauss-Lorentz mixed function fitting of the OD stretching vibration peak or OD characteristic absorption.
7. The method for in-situ detection of heavy water enrichment in electrolyzed water or electrolyzed seawater according to claim 1, characterized in that, During the electrolysis process, the electrolyte temperature is controlled to remain constant within a certain temperature range of 15 to 35℃, with fluctuations within ±0.5℃.
8. The method for in-situ detection of heavy water enrichment in electrolyzed water or electrolyzed seawater according to claim 1, characterized in that, The electrolyte used in the electrolysis of water or seawater includes fresh water, natural seawater, artificial seawater, alkaline aqueous solution, or high-salinity wastewater.
9. The method for in-situ detection of heavy water enrichment in electrolyzed water or electrolyzed seawater according to claim 1, characterized in that, The detection limit for the concentration is 0.5 at% molar fraction of heavy water; step S5 further includes: The hydrogen isotope separation factor was calculated by combining the cumulative amount of electricity generated during electrolysis, which was used to evaluate the impact of different electrode materials and electrolysis conditions on the enrichment efficiency of heavy water.
10. A system for in-situ detection of heavy water enrichment in electrolyzed water or electrolyzed seawater, characterized in that, include: The standard curve construction module is used to prepare a series of standard solutions with known heavy water mole fractions, collect the Raman spectrum and / or infrared spectrum of each standard solution, calculate the peak area ratio of the OD stretching vibration peaks corresponding to the Raman spectrum and / or calculate the peak area ratio of the OD characteristic absorption peaks corresponding to the infrared spectrum, and fit the standard curve equation between the peak area ratio and the heavy water mole fraction. The in-situ spectral acquisition module is used to place the electrolytic cell in the optical path of a Raman spectrometer or an infrared spectrometer, so that the excitation light or infrared light is focused on the electrolyte thin layer on the surface of the working electrode through the optical window. While electrolysis is in progress, the Raman spectrum and / or infrared spectrum of the electrolyte thin layer are acquired in real time at set time intervals. The ratio calculation module is used to perform baseline correction on the acquired in-situ spectral data and to calculate the peak area ratio of the OD stretching vibration peak and / or the peak area ratio of the OD characteristic absorption peak. The concentration inversion module is used to substitute the calculated peak area ratio into the standard curve equation to calculate the mole fraction of heavy water in the electrolyte at the current moment. The enrichment dynamic monitoring module is used to determine whether heavy water enrichment has occurred based on the calculated mole fraction and the preset heavy water concentration detection limit, and to output an early warning signal or automatically record the enrichment time point when heavy water enrichment occurs.