Heavy water (Deuterium oxide) is produced bydeuteriumandoxygenCompound composed of, also called deuterium oxide, molecular formula DtwoO，Relative molecular weight 20.0275, specific water (HtwoO) Ofrelative molecular mass18.0153 is about 11% higher,densityIt is also larger than ordinary water[2]Therefore, it is called heavy water.Since deuterium and hydrogen belong to the same element[2]，chemical propertyThe difference is very small, so the chemical properties of heavy water and ordinary water are also very similar,.In natural water, the content of heavy water is about 0.02%.The electrolytic rate of heavy water is lower than that of ordinary water, and it can be extracted from water by electrolysis[1]。The boiling point of heavy water is different from that of ordinary water, so it can also be purified by distillation.
In 1931, HC. Yuri and FG. Brikveld discovered deuterium in liquid hydrogen.
In 1933, GN. Lewis and RT. MacDonald obtained 0.5 ml heavy water by electrolysis,purity65.7%electrolysis0.1 g of nearly pure heavy water is obtained.
In 1934,NorwayThe world's first heavy water production plant was built by using cheap hydropower.
Physical and chemical properties
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physical property
Molecular structure data
1. Molar refractive index: 3.67
2. Molar volume (cmthree/mol）：18.0
3. Isotonic specific volume (90.2K): 52.6
4. Surface tension (dyne/cm): 72.2
5. Polarization (10-24cmthree）：1.45
No decomposition if used and stored according to specifications
Avoid contact with moisture/wet aqueous solutions andalkali metalAlkali earth metals are not miscible with many organic and inorganic active chemicals.The density at 25 ℃ is 1.1044kg/L, and the temperature at maximum density is 11.2 ℃.pKa=14.955（25 ℃）[3]。
chemical property
Calculate chemical data
1. Drainage parameter calculation reference value (XlogP)[2]：-0.5
11. Determine the number of atomic structure centers[2]：0
12. Number of uncertain atomic structure centers[2]：0
13. Determine the number of chemical bond stereocenters[2]：0
14. Uncertain number of chemical bond structural centers[2]：0
15. Number of covalent bond units[2]：1
Ecological data
Heavy water is slightly harmful. Do not discharge materials into the surrounding environment without government permission[3]。
application area
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Atomic energy technology
The main purpose of heavy water is toAtomic energy technologyIn application, it is necessary to produce powerfulnuclear weaponHeavy water is needed as an atomNuclear fissionRetarder in reaction, reducingneutronSpeed, control the nuclear fission process, and alsocoolant。Light water can also be used as a retarder, but because light water will absorb neutrons, light water reactors must be usedenriched uranium, instead of using ordinary uranium, otherwise it will not reachCritical mass。Heavy water reactorNot only ordinary uranium can be used[4]And will convert uranium-238 into nuclear bombplutonium。India, Pakistan, Israel and North Korea all make nuclear fuel in this way.To preventnucleonThe proliferation of weapons and the production and sale of heavy water are restricted in many countries.
Heavy water has a very important use in cutting-edge technology[4]。The heart of the atomic power station is the atomic reactor. In order to control the normal progress of the nuclear fission reaction in the atomic reactor, heavy water is needed as the neutronRetarderHeavy hydrogen can be obtained by electrolysis of heavy water. Heavy hydrogen is the raw material of hydrogen bomb. China has successfully exploded the first hydrogen bomb on June 17, 1967, which has increased the morale of the Chinese people. More importantly, heavy hydrogen can release huge energy when conducting nuclear fusion reaction, and will not pollute the environment. Some calculations speculate that if heavy hydrogen in seawater is used for thermonuclear reaction power generation,Its total energy is equivalent to all the oceans being turned into oil.
Tracer material
Heavy water and deuterium are valuable in studying chemical and physiological changesTracerMaterials, such as irrigating trees with dilute and heavy water, can measure that water in these plants can run for tens to tens of meters per hour[11]。Determination ofdeuteriumThe average retention time of water molecules in human body is 14 days.Replacing ordinary hydrogen with deuterium can study animal and plant digestion andthe new supersedes the oldProcess.Concentrated or pure heavy water cannot maintain the life of animals and plants, and the lethal concentration of heavy water to general animals and plants is 60%.As a component of water or other compounds, deuterium can be safely applied to patients as a beverage or injection.When water or compounds are treated by human body, the existence of deuterium will tell doctors and patients how to metabolize deuterium.At the same time, deuterium is also used for drug metabolismnuclear magnetic resonance(NMR) measured marker.Both hospital diagnostic laboratories and university laboratories use deuterium compounds in medical research (including cancer research).
After heavy water is injected into the groundwater level, the movement and distribution of groundwater in the aquifer can be directly observed[11]。A small amount of deuterium can be detected to inform scientists of the amount of water and flow at a particular location (groundwater hydrology).Hydrology using deuterium as a tracer has been used in environmental studies, water and wastewater mapping, and more recently in hydraulic fracturing monitoring (also known as "fracturing").Deuterium is used for hydraulic fracturing in natural gas exploration process of oilfield service and applicationDrilling fluidIt is used as a tracer (to determine whether the drilling fluid penetrates into the core) and in geological research.Since there is no harmful chemical substance related to deuterium oxide, and it is stableisotope。
Pharmaceutical industry
Deuterium atom (D) can slow down the speed of drug metabolism in human body.It naturally exists in the human body and can be safely used as a component of therapeutic drugs.Due to the very similar chemical properties of deuterium and Pro, deuterium can be replaced in the production of some drugs.Therefore, deuterium will not change the therapeutic effect of drugs.Research shows that deuterium containing drugs or deuterized drugs usually retain their full potency and effect, and slower metabolism of deuterium containing drugs usually brings longer effective benefits, smaller or fewer doses and fewer drugsside effect。 Deuterium oxide is used to manufacture many deuterium labeled compounds, including deuterization for drugsintermediate[12]。
Semiconductor industry
Deuterium gas (Dtwo）Used to manufacture silicon commonly found in circuit boardssemiconductorandMicrochip[13]。After deuterium annealing, deuterium atoms are replaced with deuterium to prevent chip circuits fromChemical corrosionandHot carrier effectandDeterioration。This process greatly extends and improves the semiconductor andMicrochipAnd make them smaller and have high circuit density (high-density chips).The use of deuterium instead of Pro (a common isotope of hydrogen) in semiconductors offers several benefits.First, the vibration of Si-D bondRelaxation timeIt is much shorter than the traditional Si-H bond.This means that the compound reaches the vibration equilibrium point faster.The reason is due to the quantum coupling with Si Si bond in the depth of silicon crystal.In general, the lifetime of D doped devices is much longer than that of H doped devices.It is found that there is synchronization of abnormal quantity between deuterium and silicon.This means that the two elements are very fast and very firmly combined.All these are beneficial to semiconductor chips andMicrochipIt has been found that deuterium can reduce the severity of the hot carrier effect on semiconductors and reduce the stress inducedleakage current 。Hot carrier effect and stress induced leakage current can greatly control the life of semiconductor, and are usually the main cause of on-chip faults.
Production method
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Heavy water can be produced by many methods.The original method was to useElectrolytic methodBecause the discharge rate of deuterium on the electrode is slower than that of hydrogen, it is possible to concentrate heavy water by electrolysis. Another simple method is to use heavy waterboiling pointHigher than ordinary water through repeateddistillationGet.However, these two methods are very energy consuming and have been abandoned. Later, some other better methods have been developed.Such as water hydrogen sulfide exchange method, ammonia hydrogen exchange method, hydrogen/methylamine exchange method, water hydrogen exchange method, water ammonia exchange method, etc[5]。
The water hydrogen sulfide exchange method (GS method) is the most economical heavy water production method.GS method is based on the exchange of hydrogen and deuterium between water and hydrogen sulfide.In this process, water flows to the tower bottom, andhydrogen sulfideGas circulates from tower bottom to tower top.A series of porous trays are used to promote the mixing of hydrogen sulfide gas and water.At low temperature, deuterium migrates to water, and at high temperature, deuterium migrates to hydrogen sulfide.Hydrogen sulfide gas or water with concentrated deuterium[6]。The reaction is as follows:
Water is discharged from the junction of the hot section and cold section of the first stage tower, and this process is repeated in the next stage tower.The product of the last stage (deuterium is concentrated to up to 30% water) is sent to a distillation unit for preparationreactorGrade heavy water (i.e. 99.75% deuterium oxide)[6]。
The ammonia hydrogen exchange method iscatalyzerIn the presence of, deuterium is extracted from synthesis gas through the contact between water and liquid ammonia[7]。SyngasIt is sent to the exchange tower and then to the ammonia converter.In the exchange tower, the gas flows from the tower bottom to the tower top, while the liquid ammonia flows from the tower top to the tower bottom.Deuterium is washed down from the hydrogen of synthesis gas and concentrated in liquid ammonia.The liquid ammonia then flows into the ammonia cracker at the bottom of the tower, while the gas flows into the ammonia converter at the top of the tower.It is further concentrated in later stages, and then reactor grade heavy water is produced through distillation.Synthetic gas feed can be provided by ammonia plant, which can also be built together with ammonia hydrogen exchange heavy water plant.The ammonia hydrogen exchange method can also use ordinary water as the deuterium feed source.
About 1/3200 of the water on the earth isSemiheavy water（HDO）。Semi heavy water can penetrateelectrolysisanddistillationOr chemically extracted from ordinary water.Chemical methods can be used because heavy hydrogen and ordinary hydrogen atoms have different masses, so the speed of chemical reaction is different.When the half weight water in the water reaches a certain levelconcentrationHeavy water will slowly appear due to the exchange of hydrogen atoms between water molecules.To refine pure heavy water from semi heavy water, electrolysis can also be used[1]Distillation and chemical methods.However, the energy required for electrolysis and distillation will be very huge, so generally only chemical methods will be used in this step.
toxicity
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Although heavy water is a valuable resource in cutting-edge technology, it is harmful to people. People cannot drink heavy water,microorganism、fishIn pure heavy water or water with more heavy water (more than 80%), people will die within a few hours. On the contrary, light water with less heavy water, such asSnow water, but it can stimulate biological growth[8]。
It is generally believed that heavy water does not belong toToxic SubstancesHowever, some metabolism in the human body needs light water, so if you only drink heavy water, you will get sick.Because D in heavy water has one more neutron than H, and the weight of D is twice that of Hchemical propertyCertain changes and substantial changes in physical properties occur.The various bonds of D are stronger than H, and the transfer rate of heavier D is much slower than H, resulting in thechemical reactionIt will decelerate and interfere with normal organismmetabolize[8]。
Animal experimentIt is found that heavy water can inhibit themitosis, causing deterioration of body tissues requiring rapid metabolism.After drinking only heavy water for several days, about half of the body fluid in the mice became heavy water;At this time, the symptoms begin to appear, and it needs to be quicklycell divisionThe root of hair and the gastric membrane were the first to develop problems.Originally fast growingcancer cellThe growth rate also slowed down, but the extent of the slowdown was not enough to make heavy water feasibletreatmentmethod[8]。
testing
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The concentration of heavy water can be measured by the concentration test method of equal volume mass, and the measuring device is shown in the figure[9]：
Heavy water concentration measuring device
During measurement, the same sampling tube is used, and the measured mass is equal volume mass.The test steps are[9]：
(1) Use compressed air to blow out the residual water vapor in the sampling pipe[9]；
(2) Measure the temperature of sample water with a thermometer and record it[9]；
(3) Use a micro syringe to inject sample water into the sampling tube, and stop the sample injection when the water continuously flows out from the tail end;Wipe off the residual water on the outer surface of the sampling tube outlet end with absorbent paper[9]；
(4) Remove the syringe at the inlet of the sampling tube, and wipe off the residual water on the external surface of the inlet end of the sampling tube with absorbent paper[9]；
(5) Use tweezers to place the sampling tube on the electronic balance for weighing, and then subtract the initial mass of the sample tube to get the sample mass[9]；
(6) Single component light water (H) according to the corresponding temperaturetwoO) And heavy water (DtwoO) Mass, the concentration of heavy water in the sample can be obtained by the conversion relationship between the equal volume mass and the concentration[9]。
emergency measure
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First aid measures
Inhalation: If inhaled, move the patient to fresh air[10]。
Skin contact: Take off the contaminated clothes and wash the skin thoroughly with soapy water and clean water.Get medical attention if you feel unwell[10]。
Eye contact: separate the eyelids and flush with flowing water or physiological saline.Get medical attention immediately[10]。
Ingestion: Rinse mouth, do not induce vomiting.Get medical attention immediately[10]。
Advice for protecting the rescuer: transfer the patient to a safe place.Consult a doctor.Show this chemical safety data sheet to the doctor on site[10]。
Fire fighting measures
Extinguishing agent: use water mist, dry powder, foam or carbon dioxide extinguishing agent to extinguish the fire.Avoid using direct water to extinguish the fire. Direct water may cause splashing of flammable liquid and spread the fire[10]。
Precautions and protective measures for fire fighting: firefighters must wear breathing apparatus and full body fire-fighting clothes, and extinguish the fire upwind[10]。
Move the container from the fire site to an open place as far as possible[10]。
If the container in the fire site has changed color or sounds from the safety relief device, it must be evacuated immediately[10]。
Isolate the accident site and prohibit irrelevant personnel from entering[10]。
Receive and treat fire water to prevent environmental pollution[10]。
Leakage emergency treatment
Protective measures, protective equipment and emergency response procedures for operators[10]：
It is recommended that emergency treatment personnel wear gas breathing apparatus, anti-static clothing and rubber oil resistant gloves.
Do not touch or cross the leakage.
All equipment used in operation shall be grounded.
Cut off the leakage source as much as possible.Eliminate all ignition sources.
The warning area shall be demarcated according to the influence area of liquid flow, steam or dust diffusion, and irrelevant personnel shall evacuate from crosswind and upwind to the safety area.
Environmental protection measures[10]: Collect leakage to avoid environmental pollution.Prevent leakage into sewers, surface water and groundwater.
Receiving and removal methods of leaked chemicals and disposal materials used[10]：
Small amount of leakage: collect the leaked liquid in a sealable container as far as possible.Absorb with sand, activated carbon or other inert materials and transfer to a safe place.Do not flush into the sewer.
Large amount of leakage: build a dike or dig a pit to receive.Close the drainage pipe.Cover with foam to inhibit evaporation.Use explosion-proof pump to transfer to tank car or special collector for recycling or transport to waste disposal site.
Storage and transportation
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Storage method
Keep the container sealed, put it in a tight container, and store it in a cool, dry place[3]。
Transport method
Packing method: packing according to the method recommended by the manufacturer, such as open steel drum.Ordinary wooden case outside the ampoule bottle.Screw mouth glass bottle, iron cap pressure mouth glass bottle, plastic bottle or ordinary wooden case outside metal bucket (can), etc[10]。
Transportation precautions[10]：
Transport vehicles shall be equipped with fire-fighting equipment and leakage emergency treatment equipment of corresponding types and quantities.
It is strictly prohibited to mix with oxidants, edible chemicals, etc.
The exhaust pipe of the vehicle transporting this article must be equipped with fire arresting device.
When tank (tank) trucks are used for transportation, there should be grounding chains, and hole partitions can be set in the tank to reduce static electricity generated by vibration.
It is prohibited to use mechanical equipment and tools that are easy to generate sparks for loading and unloading.
It is better to transport in the morning and evening in summer.
During transportation, it shall be protected from sun exposure, rain and high temperature.
Keep away from kindling, heat source and high temperature area during stopover.
Road transportation shall be carried out according to the specified route, and do not stay in residential areas and densely populated areas.
It is forbidden to slip during railway transportation.
It is strictly prohibited to transport in bulk by wooden boat or cement boat.Danger signs and announcements shall be posted on the means of transport according to relevant transport requirements.
