Heavy water: use - dangers

Heavy water definition

Heavy water is water with the same chemical formula as regular water (H2O); That is, it also consists of two hydrogen atoms and one oxygen atom, but it does not contain the ordinary isotope of hydrogen called Protium, but rather contains one or two of the isotopes of the hydrogen atom known as Deuterium; This is why heavy water is also known as deuterium oxide (D2O).[1]

Molecular weight of heavy water

It is indicated that the atomic weight of deuterium is 2 while the atomic weight of the ordinary hydrogen isotope protium is 1, and thus the molecular weight of heavy water is completely different from the molecular weight of ordinary water. Where the molecular weight of heavy water is 20 if it contains two deuterium atoms; Which is the sum of twice the atomic weight of deuterium 4 in addition to the atomic weight of oxygen, which is 16, while the molecular weight of ordinary water is 18; Which represents the sum of twice the atomic weight of Protium 2 plus the atomic weight of Oxygen.[2]

The percentage of heavy water in nature

Heavy water is formed naturally, but in small quantities compared to ordinary water; Where the percentage of its presence in nature is equivalent to one molecule of it compared to twenty million molecules of ordinary water, and it is indicated that heavy water does not have any radioactivity; Because deuterium is considered a stable isotope.[3]

Heavy water use

Heavy water has many uses, most notably the following:

1. Nuclear reactor applications

The following are the most important uses of heavy water in nuclear reactors: [4]

1.      slowing down the speed of neutrons in nuclear fission reactors in a process known as neutron quenching; In order to ensure an effective fission chain reaction, it is one of the two intermediates that can be used to allow a nuclear reactor to operate using natural uranium,[3] where it can interact with the isotope of uranium U235 instead of the isotope of uranium U238.[4]

2.     Coolant in nuclear reactors.

3.     Nuclear magnetic resonance spectroscopy to detect magnetic fields around the nuclei of atoms.

4.     Infrared spectroscopy instead of regular water.

5.     The production of tritium, which is one of the radioactive isotopes of hydrogen, as it is an active substance in nuclear fusion reactions, where it is formed by capturing deuterium in heavy water to a neutron.

2. Biological Studies Applications

Heavy water is used in the following biological studies:[4]

1.      It is used as a tracer to study the mechanism of some vital processes; such as respiration and photosynthesis. Interfering with human and animal metabolic rate testing; By mixing a quantity of heavy water with water containing heavy oxygen.

2.     It is involved in the preparation of many analogues of organic compounds.

Dangers of drinking heavy water

It is advised to avoid drinking heavy water because of the damage it causes to the human body as a result of the interaction of deuterium atoms in the biochemical processes inside the cells of the body, and it is noteworthy that the damage it causes depends on the amount that is drunk; Drinking one cup of it or less does not cause any harm, while drinking a large amount causes a feeling of dizziness because its density is higher than the density of normal water, which affects the fluid in the inner ear responsible for maintaining body balance. [5]

Dangers of drinking large amounts of heavy water

Drinking large amounts of heavy water for continuous periods of time leads to an increase in its percentage in the water in the body, and the following is an explanation of the extent of its danger: [5]

·       It does not pose a threat to human life as long as its percentage does not exceed 20% of the water content in the body.

·       cause significant damage if it exceeds 20%; It leads to infertility if it reaches 25%. If it reaches 50% of the water in the body, it leads to death.

·       It should be noted that these effects occur only in mammalian bodies, while the rest of the living organisms are not affected in the same way, for example, bacterial growth can increase only above them.

Heavy water uses

Deuterium oxide (D2O), called heavy water, plays an important role in heavy water nuclear reactors; Where it can be used in cooling, and controlling the movement of neutrons (in English: neutron moderator), and the following are many applications for heavy water: [6]

1.      Heavy water is used to prepare deuterium.

2.     It is used as a tracer to study the mechanism of cellular respiration and photosynthesis.

3.     D2O is used in nuclear magnetic resonance spectroscopy, which is used to study the magnetic field surrounding the nuclei of atoms.

4.     With deuterium oxide, isotopologues can be prepared for many organic compounds.

5.     Heavy water is used instead of regular water in infrared (IR) spectroscopy.

6.     It is used to slow the movement of neutrons in nuclear reactors, and this allows the neutrons to react with uranium (235U) instead of uranium (238U).

7.      The metabolic reactions that occur in the human and animal body can be studied using a solution of deuterium oxide and heavy-oxygen water; It is a type of heavy water that contains the oxygen isotopes 17O and 18O.

8.     Tritium is the active substance used to control nuclear fusion reactions, and is formed when the deuterium in heavy water obtains a neutron.

9.     Heavy water is used instead of regular water in the study of proteins using Fourier Transform Infrared Spectroscopy technology (FTIR: Fourier Transform Infrared Spectroscopy).[7]

Possibility to use heavy water for drinking

Although heavy water is not considered a radioactive substance, it is not suitable for drinking; This is because deuterium does not act like the normal hydrogen isotope known as protium in biochemical reactions, and the body is not affected much if a small amount of heavy water is drunk. negative effects on the body; As replacing 25% of the protium leads to sterility, and replacing 50% of it leads to death.[7]

Biological uses of heavy water

Deuterium oxide (D2O) in high concentrations can reduce high blood pressure caused by salt and ethanol in mice, in addition to protecting mice from gamma rays, and the use of deuterium oxide in high concentrations plays an important role in boron neutron trapping therapy. (in English: boron neutron capture therapy); This allows neutrons to penetrate into boron compounds that bind in malignant cells.[8]

References

1.      Anne Marie Helmenstine (28-1-2020), "Can You Drink Heavy Water?"، www.thoughtco.com, Retrieved 21-10-2020. Edited.

2.     Adam Augustyn (13-11-2019), "Heavy Water"، www.britannica.com, Retrieved 21-10-2020. Edited.

3.     Bethel Afework, Jordan Hanania, Kailyn Stenhouse, Jason Donev (18-5-2018), "Heavy Water"، energyeducation.ca, Retrieved 21-10-2020. Edited.

4.     "Heavy Water - Uses, Properties and Reactions", byjus.com, Retrieved 21-10-2020. Edited.

5.     Juan Ramos (14-11-2017), "Heavy Water: Here’s Why You Shouldn’t Drink Heavy Water"، sciencetrends.com, Retrieved 21-10-2020. Edited.

6.     "What is Heavy Water?", byjus.com, Retrieved 7-5-2019. Edited.

7.      Anne Marie Helmenstine (9-1-2018), "Heavy Water Facts"، www.thoughtco.com, Retrieved 7-5-2019. Edited.

8.     "Pharmacological uses and perspectives of heavy water and deuterated compounds.", www.ncbi.nlm.nih.gov, Retrieved 7-5-2019. Edited.