Vacuum distillation preparation method of deuterium-tritium-depleted water

Abstract

The invention relates to the technical field of isotope separation and special water treatment, and discloses a vacuum distillation preparation method of low-deuterium and low-tritium water, which comprises the following steps: 1, raw material pretreatment: carrying out sand filtration, activated carbon filtration and ultrafiltration treatment on raw material water to obtain pretreated water; the pretreated water, concentrated sulfuric acid and copper sulfate pentahydrate are mixed according to the mass ratio of 100: (5-15): (0.2-1.0), cooling is conducted in an ice-water bath till the temperature does not exceed 40 DEG C, and uniform stirring is conducted; and 3, low vacuum distillation: transferring the mixed system into a distillation device, adjusting the vacuum degree to 0.02-0.08 MPa, heating to 60-90 DEG C, controlling the distillation rate to be 10-20% of the volume of the raw material liquid per hour, and carrying out constant temperature distillation. The vacuum distillation preparation method of the low-deuterium and low-tritium water is low in energy consumption and low in cost, the low-vacuum-degree condition of 0.02-0.08 MPa is adopted, the distillation temperature is only 60-90 DEG C, and compared with a traditional high-vacuum and high-temperature distillation process, the energy consumption is reduced by 40% or above; meanwhile, complicated multi-stage rectification equipment is not needed, so that the equipment investment and the operation cost are obviously reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of isotope separation and special water treatment, and particularly relates to a vacuum distillation preparation method of low deuterium-tritium water. BACKGROUND

[0002] Protium, deuterium and tritium are three isotopes of hydrogen, and water composed of the three isotopes is respectively called protium water (light water), deuterium water (heavy water) and tritium water (superheavy water). The abundance of deuterium in natural water is about 150x10-6 atom%, and the abundance of tritium is extremely low but shows a growth trend. Low deuterium-tritium water (also called deuterium-tritium-poor water) refers to water with deuterium and tritium abundance lower than that of natural water, and low deuterium-tritium water with deuterium and tritium content less than -150‰ has important application value in high-tech fields such as life science, nuclear science, medicine and agricultural science, and can be used in cell repair research, extraction of effective components of Chinese herbal medicine, and cultivation of crops for yield increase. 4

[0003] At present, the preparation methods of low deuterium-tritium water mainly include electrolysis method, rectification method, chemical exchange method, membrane separation method and porous material adsorption method, etc. Among them, the rectification method is a commonly used basic method in industry because of its simple principle and strong controllability. The core principle of the rectification method is to realize separation by using the difference in vapor pressure of hydrogen isotope compounds. However, the existing rectification technology has obvious defects. On the one hand, the traditional distillation method needs to be carried out under high vacuum degree and high energy consumption conditions, and multi-stage rectification is required, which leads to large equipment investment and high operation cost, and it is difficult to realize large-scale low-cost production. On the other hand, the isotopic separation coefficient of a single distillation system is small, and it is difficult to reduce the deuterium and tritium content to a high purity level of less than -150‰.

[0004] In the prior art, although there are attempts to prepare low deuterium water by vacuum distillation, such as the method for preparing low deuterium-tritium water by high-vacuum vaporization of water disclosed by Ukraine and the technology for obtaining low deuterium water by vacuum distillation of tap water adopted by Romania, there are still problems such as high requirement for vacuum degree (high energy consumption), limited product purity (difficult to reach -150‰) and poor process stability. In addition, the application of the mixed system of sulfuric acid and copper sulfate in the distillation field is mainly concentrated in the sample digestion process in the Kjeldahl nitrogen determination method, and the catalytic action of copper sulfate and the oxidative dehydration action of sulfuric acid are used to accelerate the decomposition of organic matter, but there is no related report on the application of the mixed system to hydrogen isotope separation to improve the preparation efficiency and purity of low deuterium-tritium water.

[0005] Therefore, it is a technical problem to be solved in the field to develop a method for stably preparing low deuterium-tritium water with deuterium and tritium content less than -150‰, which has low energy consumption and simple process. SUMMARY

[0006] ​The present application aims to provide a vacuum distillation preparation method of low deuterium-tritium water, so as to solve the problems of high energy consumption, complex equipment, insufficient product purity and the like in the prior art.

[0007] In order to solve the above technical problems, the present application provides the following technical scheme: a vacuum distillation preparation method of low deuterium-tritium water, comprising the following steps: Step 1: raw material pretreatment: the raw material water is subjected to sand filtration, activated carbon filtration and ultrafiltration treatment to obtain pretreated water; Step 2: mixed system preparation: the pretreated water, concentrated sulfuric acid and copper sulfate pentahydrate are mixed in a mass ratio of 100:5-15:0.2-1.0, and the mixed system is cooled to a temperature not higher than 40 DEG C in an ice water bath and uniformly stirred; Step 3: low vacuum distillation: the mixed system is transferred into a distillation device, the vacuum degree is adjusted to 0.02-0.08 MPa, and the temperature is adjusted to 60-90 DEG C, and the distillation rate is controlled to be 10%-20% of the volume of the raw material per hour, and constant temperature distillation is carried out; Step 4: condensation collection: the distillation vapor is cooled to 20-30 DEG C through a condenser tube, and the initial product is collected; Step 5: purification and detection: after the initial product is treated by ion exchange resin, the deuterium-tritium content is detected, and the fraction with a deuterium-tritium content less than-150‰ is collected as the low deuterium-tritium water.

[0008] Preferably, the conductivity of the pretreated water in step 1 is ≤10 μS / cm, and the total organic matter content is ≤5 mg / L.

[0009] Preferably, the mass fraction of the concentrated sulfuric acid in step 2 is 98%, and the purity of the copper sulfate pentahydrate is analytical pure.

[0010] Preferably, the distillation device in step 3 is a vacuum distillation flask equipped with a precision vacuum gauge and a temperature control system, and the stirring rate during the distillation process is 100-300 r / min.

[0011] Preferably, the ion exchange resin in step 5 is a mixed bed of 001x7 type cation exchange resin and 201x7 type anion exchange resin.

[0012] Preferably, the deuterium-tritium content is detected by a stable isotope ratio mass spectrometry.

[0013] Compared with the prior art, the present application has the following beneficial effects: First, the present application has low energy consumption and low cost: under the condition of a low vacuum degree of 0.02-0.08 MPa, the distillation temperature is only 60-90 DEG C, which is 40% or more lower than that in the traditional high vacuum and high temperature distillation process; and at the same time, no complex multi-stage rectification equipment is needed, so that the equipment investment and operation cost are significantly reduced.

[0014] Second, the separation efficiency of the present application is high, and the product purity is high: through the synergistic effect of the sulfuric acid-copper sulfate mixed system, copper sulfate as a catalyst can accelerate the separation process of hydrogen isotopes, sulfuric acid can reduce the hydrogen bond interaction between water molecules, increase the vapor pressure difference of hydrogen and deuterium, tritium, and make the isotopic separation coefficient increase by more than 30%, which can stably prepare low deuterium and tritium water with deuterium and tritium content less than-150‰, to meet the needs of high-end scientific research and medical fields.

[0015] Third, the process of the present application is simple and stable: the preparation steps of the present application are simple, the key parameters are easy to control, the existence of the mixed system can avoid the problems of violent boiling and scaling during distillation, and the process stability is good, which is suitable for large-scale continuous production. Fourth, the product of the present application is safe: through subsequent ion exchange resin treatment, trace amounts of sulfate and copper ions in the product can be completely removed, and the product meets the secondary water standard specified in GB / T 6682, and can be directly applied in various fields. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 The preparation flowchart of the present application is shown in the following. DETAILED DESCRIPTION

[0017] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0018] Example 1 The following steps are used to prepare low deuterium and tritium water in this embodiment: Step one: raw material pretreatment: take 10L of natural water, and sequentially pass through sand filtration (filter material particle size 0.5-1mm), activated carbon filtration (granular activated carbon particle size 2-4mm), and ultrafiltration (membrane pore size 0.01μm) to remove suspended solids, organic matter and other impurities, to obtain pretreated water, the conductivity of which is 5μS / cm, and the total organic matter content is 2mg / L, to ensure the purity of the raw material to avoid the influence of impurities on the distillation effect; Step two: mixed system preparation: under ice water bath condition, 10L of pretreated water was transferred into a 50L vacuum distillation flask, 1.0kg of 98% concentrated sulfuric acid was slowly added (raw material water to sulfuric acid mass ratio 100:10), after uniform stirring, 50g of analytical pure copper sulfate pentahydrate was added (raw material water to copper sulfate mass ratio 100:0.5), continue to stir until completely dissolved, control the temperature of the mixed solution not to exceed 35℃, prevent the dilution of sulfuric acid from causing water to vaporize in advance due to heat release, among which the copper sulfate acts as a catalyst to improve the isotopic separation efficiency of the distillation process, and the sulfuric acid is used to adjust the acidity of the system, reduce the hydrogen bond interaction between water molecules, and increase the vapor pressure difference of hydrogen, deuterium and tritium isotopes; Step three: low vacuum distillation: install the distillation device, connect the condenser tube and the receiving bottle, start the vacuum pump to adjust the vacuum degree of the distillation system to 0.05MPa, turn on the heating device and the stirrer (stirring rate 200r / min), ensure uniform temperature of the system, heat the mixed system to 75℃, control the distillation rate at 1L / h (10% of the raw material volume), and carry out constant temperature distillation; Step four: condensation collection: the distillation vapor is cooled to 25℃ by the condenser tube, and the initial product low deuterium tritium water is collected; Step five: purification and detection: the initial product is passed through a mixed bed of cation exchange resin (001x7 type strong acid styrene) and anion exchange resin (201x7 type strong base styrene) to ensure the removal of trace sulfate and metal ions, then stable isotope ratio mass spectrometry (according to ISO 13166:2020 standard) is used to detect the deuterium tritium content, the result shows that the deuterium tritium content is -168‰, which meets the target requirements.

[0019] Example 2 This example uses the following steps to prepare low deuterium tritium water: Step one: raw material pretreatment: take 10L of tap water, filter through sand, activated carbon, and ultrafiltration to obtain pretreated water, the conductivity of which is 8μS / cm, and the total organic matter content is 3mg / L; Step two: mixed system preparation: under ice water bath condition, 10L of pretreated water was transferred into a 50L vacuum distillation flask, 1.0kg of 98% concentrated sulfuric acid was slowly added (raw material water to sulfuric acid mass ratio 100:10), after uniform stirring, 50g of analytical pure copper sulfate pentahydrate was added (raw material water to copper sulfate mass ratio 100:0.5), continue to stir until completely dissolved, control the temperature of the mixed solution not to exceed 35℃, prevent the dilution of sulfuric acid from causing water to vaporize in advance due to heat release, among which the copper sulfate acts as a catalyst to improve the isotopic separation efficiency of the distillation process, and the sulfuric acid is used to adjust the acidity of the system, reduce the hydrogen bond interaction between water molecules, and increase the vapor pressure difference of hydrogen, deuterium and tritium isotopes; Step three: low vacuum distillation: start the vacuum pump to adjust the vacuum degree to 0.02MPa, turn on the heating and stirring (stirring rate 100r / min), heat to 90℃, control the distillation rate at 2L / h (20% of the raw material volume), constant temperature distillation; Step four: condensation collection: the vapor is cooled to 30℃ by the condenser tube, and the initial product is collected; Step five: purification detection: after the initial product is treated by the mixed bed of ion exchange resin, the deuterium-tritium content is-156 ‰, which meets the target requirements.

[0020] Example 3 In this embodiment, low deuterium-tritium water is prepared by the following steps: Step one: raw material pretreatment: take 10 L of pure water, which is pretreated by ultrafiltration, as pretreated water, and detect that the conductivity is 2 μS / cm and the total organic matter content is 1 mg / L; Step two: mixed system preparation: under the condition of ice water bath, 10 L of pretreated water is added to a 50 L vacuum distillation flask, 1.5 kg of 98% concentrated sulfuric acid (raw material water to sulfuric acid mass ratio 100:15) is slowly added, 100 g of analytical pure copper sulfate pentahydrate (raw material water to copper sulfate mass ratio 100:1.0) is added after stirring and dissolving, and the temperature is controlled to be not more than 30℃; Step three: low vacuum distillation: start the vacuum pump to adjust the vacuum degree to 0.08 MPa, start heating and stirring (stirring rate 300 r / min), heat to 60℃, control the distillation rate to be 1.5 L / h (15% of the volume of the raw material), and constant temperature distillation; Step four: condensation collection: the steam is cooled to 20℃ by a condenser tube, and the initial product is collected; Step five: purification detection: after the initial product is treated by the mixed bed of ion exchange resin, the deuterium-tritium content is-172 ‰, which meets the target requirements.

[0021] Detection method and standard: In the present application, the deuterium-tritium content of low deuterium-tritium water is detected by stable isotope ratio mass spectrometry (IRMS), according to ISO13166:2020 “Determination of Deuterium Isotopes in Water-Mass Spectrometry” and GB / T 37848-2019 “Water Isotope Measurement Method”, the specific steps are: the purified sample is converted into H2 gas by high temperature cracking, the D / H ratio is measured by high precision mass spectrometer (such as ThermoScientific Delta V), expressed in δD (unit ‰), the deuterium-tritium content is calculated, and the pH value, conductivity, heavy metal content and other physical and chemical indexes of the sample are detected during the detection process to ensure that the product meets the requirements of GB 5749-2006 “Drinking Water Health Standards”.

[0022] Although the embodiments of the present application have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to the embodiments without departing from the principles and spirit of the present application. The scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A method for producing low deuterium-tritium water by vacuum distillation, characterized by: The method comprises the following steps: Step 1: raw material pretreatment: the raw water is treated by sand filtration, activated carbon filtration and ultrafiltration to obtain pretreated water; Step 2: mixed system preparation: the pretreated water, concentrated sulfuric acid and copper sulfate pentahydrate are mixed in a mass ratio of 100:5-15:0.2-1.0, and the mixed system is cooled to a temperature not higher than 40 DEG C in an ice water bath and uniformly stirred; Step 3: low vacuum distillation: the mixed system is transferred into a distillation device, the vacuum degree is adjusted to 0.02-0.08 MPa, heating is performed to 60-90 DEG C, the distillation rate is controlled to be 10%-20% of the volume of the raw material per hour, and constant temperature distillation is performed; Step 4: condensation collection: the distillation vapor is cooled to 20-30 DEG C by a condenser tube, and the initial product is collected; Step 5: purification and detection: after the initial product is treated by ion exchange resin, the deuterium-tritium content is detected, and the fraction with a deuterium-tritium content less than-150 ‰ is collected, which is low deuterium-tritium water.

2. The method of claim 1, wherein the vacuum distillation is performed at a temperature of 100- 200°C and a pressure of 10- 1000 Pa. The conductivity of the pretreated water in step 1 is less than or equal to 10 muS / cm, and the total organic matter content is less than or equal to 5 mg / L.

3. The method for preparing low-deuterium-tritium water by vacuum distillation according to claim 1, characterized in that: In step 2, the mass fraction of the concentrated sulfuric acid is 98%, and the purity of the copper sulfate pentahydrate is analytical pure.

4. The method of claim 1, wherein the vacuum distillation is performed at a temperature of 100- 200°C and a pressure of 10- 1000 Pa. In step 3, the distillation device is a vacuum distillation flask equipped with a precision vacuum gauge and a temperature control system, and the stirring rate during distillation is 100-300 r / min.

5. The method of claim 1, wherein the vacuum distillation is performed at a temperature of 100- 200°C and a pressure of 10- 1000 Pa. In step 5, the ion exchange resin is a mixed bed of 001x7 type cation exchange resin and 201x7 type anion exchange resin.

6. The method of claim 1, wherein the vacuum distillation is performed at a temperature of 100- 200°C and a pressure of 10- 1000 Pa. The deuterium-tritium content detection is performed by using a stable isotope ratio mass spectrometry.

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