Do you know, dear readers, that the health and longevity of our body depend on three saving systems: immune, antioxidant and detoxifying?
The activity of each of them is a complex biological mechanism, depending on different components and circumstances.
But the common factor on which the coordinated operation of these systems depends is the presence in them of a universal chemical element. Selenium what is it beneficial features, why the body needs it, what selenium deficiency and its deficiency leads to, today in the article.
The lack of selenium in the body immediately affects the state of health, even the air we breathe becomes a real poison against the background of a lack of selenium, its active forms not only turn into a destroyer of vitamins, but also disrupt the system for removing waste and toxins from the body.
Universal chemical element Selenium was discovered and described in the 19th century. According to their own chemical properties it is a non-metal, although it has an unusually beautiful iridescent metallic tint. It is a semiconductor due to its physical properties.
There is little of it in nature. But in places of volcanic eruptions, in large quantities The presence of selenium in the soil is noted, so both flora and fauna are rich in it.
This amazing element was considered a strong poison for a long time, and was treated with caution until it was rediscovered in 1973 and they found out how important it is for life human body and animals.
Now selenium is rightfully considered a chemical element of health and longevity, because it was found in almost all enzymes and hormones. The functioning of all systems of the human body depends on this substance.
In some cells or systems, selenium is present as a substance, in others - as a component of enzymes. Experts have calculated that it is present in 200 enzymes, and if there is a deficiency of selenium in the body, these enzymes cannot be synthesized.
Selenium is concentrated in different organs in different ways; it is more concentrated in the brain, kidneys, liver, seminal fluid, and cartilage tissue.
Nature has assigned an important role to selenium - protection from the destructive effects of heavy metals (arsenic, cadmium, mercury, lead, thallium) and control of all creative processes in our body.
This essential microelement is considered an element of longevity, which is due to its unique properties. Selenium takes part in the synthesis of the peptide glutathione, which performs the most important role in the course of redox reactions, holds the shield of the immune system, saving us from infections, cancer and early aging.
Selenium protects the human body at the intracellular level, it controls genetic disorders, “monitors” the health of chromosomes. It has antibacterial and antiviral properties, antitumor and anti-inflammatory, anti-stress and antipoptic effects.
Selenium performs numerous functions in the body:
☀ strengthens the body’s immunity (stimulates the formation of antibodies, white blood cells, killer cells, macrophages and interferon, participates in the production of red blood cells),
☀ is a strong antioxidant (prevents the development of tumor processes and aging of the body, neutralizes and removes foreign substances, activates vitamin E),
☀ reduces the risk of developing cardiovascular diseases (prevents muscular dystrophy of the heart, neutralizes toxins, stimulates hemoglobin synthesis, participates in the production of red blood cells and coenzyme Q10),
☀ acts as a strong antitumor factor (prevents and stops the development of malignant tumors),
☀ is part of most hormones, enzymes and some proteins,
☀ stimulates metabolic processes in the body,
☀ protects the body from the toxic effects of mercury, cadmium, lead, thallium and silver,
☀ stimulates reproductive function (part of sperm),
☀ stabilizes work nervous system,
☀ normalizes the functioning of the endocrine system,
☀ reduces the severity of inflammatory processes
☀ has a beneficial effect on the condition of the skin, nails and hair.
How does selenium work in the body? Scientists note that despite the scanty content of selenium in the body, its role in maintaining the vital functions of all systems and organs is great. Everyone knows that a person needs energy to live, move, and work. It has now been precisely established that almost all the energy produced by cell mitochondria occurs only with the participation of selenium (i.e. 85%)! Energy is needed by all organs:
All these processes in the body take place with the participation of selenium, and if there is not enough of it, then the activity of any organ will be disrupted, which is accompanied by a lot of unpleasant symptoms, the appearance of chronic fatigue and the onset of various diseases.
Imagine, in every cell of our body, 1 million flows in just one minute. chemical reactions. And in one second, thousands of free radicals appear. These are defective molecules that lack one electron and they barbarously take it away from other molecules, thereby turning them into the same barbarians - free radicals.
But we remember that for the construction of all cells and tissues, only stable and not defective molecules are needed. But if the process of formation of free radicals progresses, this will cause a response - destruction of tissues and cells of the body.
It inhibits the growth of radicals due to the action of the body's antioxidant system, which includes vitamin C, A, E and the element selenium. And only in the presence of selenium does the synthesis of enzymes involved in antioxidant protection occur. Therefore, selenium is one of the main links for immune strength and detoxification.
It protects the body from contaminated water and food, neutralizes tobacco smoke, exhaust gases, and all heavy metals that quietly accumulate in the body (lead, arsenic, mercury, cadmium).
Now scientists say with confidence that selenium controls the entire life cycle of a cell, from its birth to death.
Scientists have found that in conditions of selenium deficiency, the immune system cannot fully perform its functions. Failure after failure begins:
The process of iodine metabolism and the functioning of the thyroid gland are disrupted, since its coordinated work depends on the presence of iodine. And the thyroid gland regulates metabolic processes, so the process of inhibiting the growth and development of the body occurs.
Selenium deficiency in the body causes many diseases:
We found out that selenium is important element, which is called a biocorrector, since not a single cell is able to work without its presence. Chemical element selenium:
The heart is very sensitive to the selenium content in the cells; if its level drops to 45 mcg/kg, then there is an immediate risk of heart failure. Acute heart failure occurs if selenium levels drop to 20 mcg/kg, resulting in cardiac arrest.
Scientists have established a natural relationship between selenium content in the blood and the development of coronary heart disease. Practical observations have shown that heart disease is 70 times more likely to occur in people with low selenium levels.
Coenzyme Q10, which protects the heart muscle from oxygen deficiency and is involved in the restoration of the heart after a heart attack, is also synthesized in the body only in the presence of the element selenium.
The thyroid gland plays a leading role in the human body in the energy metabolism of cells, regulating the functioning of all organs and systems, and for this it has to synthesize some hormones.
One of these hormones is T4, which, after donating one iodine atom, is converted into the active hormone triiodothyronine, which is involved in energy metabolism. This process occurs with the participation of selenium.
If there is not enough selenium in the thyroid cells, then the hormone triiodothyronine is not synthesized. If this hormone is not present, then there is no energy in the cells of the body. And then the human brain sends a signal to the thyroid gland that its work is unproductive. The thyroid gland responds by working hard and increases in size or forms nodules. But there is still not enough selenium, and problems have appeared in the thyroid gland due to its deficiency.
Recent research by scientists indicates that thyroid diseases are often caused not by iodine deficiency, but by selenium deficiency. The presence of selenium, which has a pronounced antioxidant property, protects thyroid cells and tissues, reduces the inflammatory process, and destroys free radicals.
The chemical element selenium, with the help of the thyroid gland and iodine, controls the vital functions of our body, regulating metabolism, immunity, and the functioning of brain cells...
The incidence of cancer depends on the level of selenium in the body; this relationship has already been proven by scientists. When selenium levels are normal, it inhibits the growth of an emerging tumor.
Atypical or cancerous cells are formed in all people; such cells are born every 10 minutes. But in the presence of selenium, the body immediately produces special enzymes that break down cancer cells.
But if there is a deficiency of selenium in the body, then such enzymes cannot be produced, and atypical cells continue to grow and multiply, forming a tumor. In the process of reproduction cancer cells Toxic substances accumulate, which, also due to a lack of selenium, are not neutralized and continue to accumulate in the body.
Research by American scientists, conducted for more than 10 years, studying the effect of selenium on the human body showed that among people with cancer, in the group taking the element 200 mcg per day, mortality was reduced by 50% compared to those studied who did not take the drug. Among the people studied were patients with colon, lung, and prostate cancer.
This is interesting:
“Scientists have recently found that serum selenium concentrations below 45 μg/L lead to the development of tumors, both benign and malignant.”
Daily requirement of selenium. The fact is that the body is not able to synthesize selenium and receives it from the food it eats. On average, the human body should receive up to 100 mcg/day: adult men require 70 mcg, women require up to 55 mcg, and pregnant and lactating women require up to 75 mcg. If we take into account that a person will receive this amount of selenium daily, then over the course of his entire life, the amount of selenium eaten will not exceed 1/2 teaspoon.
But unfortunately, the statistics for Russia are completely different. Experts emphasize that on average, Russian residents consume only 30 mcg of selenium in food, so 80% of residents are deficient in selenium.
A person's need for selenium is satisfied 90% through food and 10% through water. It is believed that the most a large number of Selenium is found in Brazil nuts, onions and garlic.
It is important to consider whether there is a natural deficiency of selenium? If there is a lack of selenium in the biosphere of your region, then no matter how much you eat garlic and onions grown on your plot, there will be no benefit or it will be negligible.
And the use of chemicals further reduces the level of assimilable selenium in the soil, and therefore in the plants grown on this land. The amount of selenium in environment affected by forest fires, burning grass and dry leaves.
Data from the Research Institute of Nutrition of the Russian Academy medical sciences, they say that almost throughout the entire territory of Russia there is a deficiency of selenium in the soil. Especially in Transbaikalia and Buryatia, studies have confirmed the low level of biologically active selenium in the soil, up to 10 mcg/kg, which causes diseases in humans, animals and plants.
Low levels of selenium are observed in Udmurtia, the Northwestern region of the country (Leningrad region, Karelia), and the Upper Volga region (Ivanovo, Kostroma, Yaroslavl regions).
In people living in areas with low selenium content in the environment, diseases of the stomach and intestines, liver and genitourinary system progress much more often; selenium deficiency manifests itself in the condition of the skin, nails, hair, teeth, and bones.
What are selenium pits? Scientists identify several periods in a person’s life when selenium is very, very necessary for the body:
- “newborns, from birth to 2 years;
- at puberty from 11-20 years;
- “Christ’s age” (30 - 33 years), when the aging process of the body begins;
- the period of pregnancy is especially dangerous if this period coincides with the age of Christ;
- climacteric periods in women and men and beyond, when the content of selenium in the blood plasma and connective tissue becomes low (after 70 years).”
These periods, coinciding with selenium deficiency, are a huge risk factor for the onset of various diseases.
Therefore, scientists are raising the question of carrying out the selenization of the country, as is done in other countries. CEO Cardiology Center of Moscow, Academician E. Chazov, claims that if we launch a program in our country to replenish selenium deficiency, then in just one year, about 600 thousand people suffering from heart disease can be saved.
But in Finland this program operates on a national scale. There, selenium is added during food production and cooking. The statistics show amazing results:
To maintain your health and well-being in good condition, you need a certain balance of the chemical element selenium in the body. The point is that this unique element shows his cunning. Not only a lack of selenium, but also an excess of selenium in the body can lead to poor health.
Therefore, you need to be careful and try to comply with the daily requirement of selenium, which was mentioned above.
Excess selenium in the body can occur in workers who come into contact with this element: in the electronics, glass, paint and varnish industries. For those who permanently live in areas of the country with active volcanoes (Kuril Islands, Kamchatka).
Selenium overdoses occur when taking dietary supplements, when a person takes several nutritional supplements containing selenium at once.
It must be remembered that long-term consumption of selenium in high doses, up to 200 mcg/day, can cause poisoning, which manifests itself in nausea and abdominal pain, accompanied by diarrhea. Irritability and neuropathy, a characteristic garlicky breath odor and a metallic taste often occur.
Excess selenium is also reflected on the skin in the form of peeling and dermatitis, hair may fall out, nails may peel, and tooth enamel may be damaged.
Health problems associated with excess selenium in the body are extremely rare. And yet, accepting nutritional supplements, do not forget about a possible overdose, strictly follow the instructions, or consult your doctor.
I wish you health, dear readers!
☀ ☀ ☀
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Selenium(Selenium), Se, chemical element of group VI of the periodic system of Mendeleev; atomic number 34, atomic mass 78, 96; predominantly non-metallic. Natural Selenium is a mixture of six stable isotopes - 74 Se (0.87%), 76 Se (9.01%), 77 Se (7.58%), 78 Se (23.52%), 80 Se (49. 82%), 82 Se (9.19%). From radioactive isotopes highest value has 75 Se with a half-life of 121 days. The element was discovered in 1817 by I. Berzelius (the name is given from the Greek selene - Moon).
Distribution of Selenium in nature. Selenium is a very rare and trace element, its content is earth's crust(clark) 5·10 -6% by weight. The history of selenium in the earth's crust is closely related to the history of sulfur. Selenium has the ability to concentrate and, despite its low clarke, forms 38 independent minerals - natural selenides, selenites, selenates and others. Isomorphic impurities of Selenium in sulfides and native sulfur are characteristic.
Selenium migrates vigorously in the biosphere. The source for the accumulation of Selenium in living organisms are igneous rocks. rocks, volcanic smoke, volcanic thermal waters. Therefore, in areas of modern and ancient volcanism, soils and sedimentary rocks are often enriched with Selenium (on average in clays and shales - 6·10 -5%).
Physical properties of Selenium. Configuration of the outer electron shell of the Se atom 4s 2 4p 4 ; two p-electrons have paired spins, and the other two have unpaired spins, so Selenium atoms are able to form Se 2 molecules or chains of Se n atoms. Chains of Selenium atoms can be closed into ring molecules Se 8 . The diversity of the molecular structure determines the existence of Selenium in various allotropic modifications: amorphous (powdery, colloidal, glassy) and crystalline (monoclinic α- and β-forms and hexagonal γ-forms). Amorphous (red) powdered and colloidal Selenium (density 4.25 g/cm 3 at 25 ° C) is obtained by reduction from a solution of selenous acid H 2 SeO 3, rapid cooling of Selenium vapor and other methods. Glassy (black) Selenium (density 4.28 g/cm 3 at 25 °C) is obtained by heating any modification of Selenium above 220 °C, followed by rapid cooling. Vitreous Selenium has a glassy luster and is fragile. Thermodynamically, hexagonal (gray) Selenium is the most stable. It is obtained from other forms of Selenium by heating until melting with slow cooling to 180-210 ° C and holding at this temperature. Its lattice is built from parallel spiral chains of atoms. The atoms within the chains are bonded covalently. Lattice constants a = 4.36 Å, c = 4.95 Å, atomic radius 1.6 Å, ionic radii Se 2- 1.98 Å and Se 4+ 0.69 Å, density 4.807 g/cm 3 at 20 °C, melting point 217 °C, boiling point 685 °C. Selena vapors are yellowish in color. In pairs, four polymer forms Se 8 = Se 6 = Se 4 = Se 2 are in equilibrium. Above 900 °C Se 2 dominates. The specific heat capacity of hexagonal Selenium is 0.19-0.32 kJ/(kg K), at -198 - + 25 °C and 0.34 kJ/(kg K) at 217 °C; thermal conductivity coefficient 2.344 W/(m K), temperature coefficient of linear expansion at 20 °C: hexagonal monocrystalline Selenium along the c-axis 17.88·10 -6, perpendicular to the c-axis 74.09·10 -6, polycrystalline 49, 27·10 -6; isothermal compressibility β 0 = 11.3·10 -3 kbar -1 ; coefficient of electrical resistance in the dark at 20 °C 10 2 -10 12 ohm cm. All modifications of Selenium have photoelectric properties. Hexagonal Selenium up to the melting point is an impurity semiconductor with hole conductivity. Selenium is diamagnetic (its vapors are paramagnetic).
Chemical properties of Selenium. Selenium is stable in air; oxygen, water, salt and dilute sulfuric acid have no effect on it, soluble in concentrated nitric acid and aqua regia, dissolves in alkalis with oxidation. Selenium in compounds has oxidation states -2, + 2, + 4, +6. Ionization energy Se 0 → Se 1+ → Se 2+ → Se 3+, respectively, 0.75; 21.5; 32 ev.
With oxygen, Selenium forms a series of oxides: SeO, Se 2 O 3, SeO 2, SeO 3. The last two are anhydrides of selenic H 2 SeO 3 and selenic H 2 SeO 4 acids (salts - selenites and selenates). SeO 2 is the most stable. With halogens, Selenium gives compounds SeF 6, SeF 4, SeCl 4, SeBr 4, Se 2 Cl 2 and others. Sulfur and tellurium form a continuous series of solid solutions with Selenium. With nitrogen, Selenium gives Se 4 N 4, with carbon -CSe 2. Compounds with phosphorus P 2 Se 3, P 4 Se 3, P 2 Se 5 are known. Hydrogen interacts with Selenium at t>=200 °C, forming H 2 Se; a solution of H 2 Se in water is called hydroselenic acid. When interacting with metals, Selenium forms selenides. Numerous complex compounds of Selenium have been obtained. All selenium compounds are poisonous.
Getting Selenium. Selenium is obtained from waste from sulfuric acid, pulp and paper production and anode sludge from electrolytic refining of copper. Selenium is present in sludge along with sulfur, tellurium, heavy and noble metals. To extract Selenium, the sludge is filtered and subjected to either oxidative roasting (about 700 °C) or heating with concentrated sulfuric acid. The resulting volatile SeO 2 is captured in scrubbers and electrostatic precipitators. Technical selenium is precipitated from solutions with sulfur dioxide. Sintering of sludge with soda is also used, followed by leaching of sodium selenate with water and separating selenium from the solution. To obtain high purity Selenium used as semiconductor material, rough Selenium is refined by vacuum distillation, recrystallization and others.
Application of Selenium. Due to its low cost and reliability, Selenium is used in converter technology in rectifying semiconductor diodes, as well as for photoelectric devices (hexagonal), electrophotographic copying devices (amorphous Selenium), the synthesis of various selenides, as phosphors in television, optical and signal devices, thermistors, etc. n. Selenium is widely used for decolorizing green glass and producing ruby glasses; in metallurgy - to give cast steel a fine-grained structure, improve mechanical properties stainless steels; V chemical industry- as a catalyst; Selenium is also used in pharmaceutical industry and other industries.
Selenium in the body. Most living creatures contain from 0.01 to 1 mg/kg Selenium in their tissues. It is concentrated by some microorganisms, fungi, marine organisms and plants. Legumes (for example, astragalus, neptunia, acacia), cruciferous, madder, and asteraceae are known to accumulate Selenium up to 1000 mg/kg (on a dry weight basis); Selenium is an essential element for some plants. Various organoselenium compounds, mainly selenium analogues of sulfur-containing amino acids - selencysthionine, selenhomocysteine, methylselenomethionine, were found in concentration plants. An important role in the biogenic migration of selenium is played by microorganisms that reduce selenites to metallic selenium and oxidize selenides. There are biogeochemical provinces of Selene.
The requirement of humans and animals for Selenium does not exceed 50-100 mcg/kg of diet. It has antioxidant properties, increases the perception of light by the retina, and affects many enzymatic reactions. When Selenium content in the diet is more than 2 mg/kg, acute and chronic forms of poisoning occur in animals. High concentrations of Selenium inhibit redox enzymes, disrupt the synthesis of methionine and the growth of supporting tissues, and cause anemia. The lack of Selenium in feed is associated with the appearance of so-called white muscle disease of animals, necrotizing liver degeneration, and exudative diathesis; Sodium selenite is used to prevent these diseases.
The metal received its own name in 1817 - selenium. Chemical element called in Greek, translated means “Moon”. The name is tellurium ancient language personified the Earth. So, even after the elements were officially separated, they remained together.
How did it happen discovery of selenium? It was discovered in sediment during a study of sulfuric acid produced in the town of Grisholm. The red-brown mass was calcined. It smelled like radish. Its aroma was also present in pyrite mines - a storehouse of tellurium. Scientists thought it was his smell.
But it was not possible to isolate tellurium from the sediment. Chemists Jens Berzelius and Gottlieb Hahn realized that they had discovered a new element. It's clear what it smells like. What are the other properties of metal? Are there any practical use?
Chemical and physical properties Selena
Selenium – element 16th group of the periodic table. The column contains chalcogens, that is, ore-forming substances. Such is selenium, which occupies 34th place in the table.
Along with it is not only tellurium, which is similar in properties, but also sulfur. Selenium has also been confused with it more than once. Elements tend to occur together. The 34th metal is an impurity in native and sulfide minerals.
Five stable isotopes of selenium, that is, its varieties, have been found in nature. Scientists call them modifications. Only one of them is metallic - this gray selenium. Its crystal lattice is hexagonal.
It consists of hexagonal prisms. The atoms are located at the center of their bases. Externally, the material resembles, the color is darkened, the shine is pronounced.
The metal quickly sinks in water, unlike the amorphous modification. It is in a powdery state. The last one is fine particles, suspended in a homogeneous medium. This is what water becomes. The powder can remain on its surface for several hours, only then slowly settles.
If color characteristics of selenium metallic - “gray”, then the amorphous element is purely red, or with a brown, almost black tint. The substance darkens when heated. To soften, 50 degrees Celsius is enough. In heat, amorphous selenium becomes sticky and viscous.
Chemical element selenium It can also be glassy. The same 50 degrees is no longer an indicator of softening, but, on the contrary, of hardening of the substance. Its glass, black color, conchoidal fracture. This means that the depressions formed when the surface is damaged resemble the shape of a shell.
The modification liquefies, heating up to 100 degrees. In a plastic state glassy selenium easily stretches into thin threads, similar to how confectionery caramel hardens.
The 4th type of element is colloidal. Selenium formula allows it to dissolve in water. That is, the modification is not solid, but is represented by a solution. It is reddish and capable of fluorescing, that is, spontaneously glowing. To do this, you need a constant source of rays, for example, emanating from.
It also occurs crystalline selenium. In the form of metal, the element resembles nuggets. The crystalline modification is associated with yields precious stones. The aggregates are monoclinic, that is, inclined in one direction.
The color of the crystals is scarlet or cherry. The modification is destroyed at a temperature of 120 degrees Celsius, becoming hexagonal. The metallic form of the 34th element is, in general, the most dynamically stable of the 5. All isotopes tend towards it.
Electronic form of the element selenium in any of the modifications is the same - 4s 2 4p 4. This determines the typical oxidation state of the substance – 2. Electronic formula of selenium atom, more precisely, its external level, makes it predictable and chemical interactions 34th element.
It reacts with all metals, forming selenides. Easily compatible with halogens. The interaction takes place when room temperature. In concentrated sulfuric acid, the 34th element dissolves even at minus. A green solution is formed.
Uses of selenium
Though selenium solution in sulfuric acid and green, but industrialists use the element precisely to neutralize this color. We are talking about the glass industry and ceramics production.
Many enamels have a greenish tint due to the presence of iron. Selenium discolors materials. If you add to the 34th element, you get the famous ruby.
Selenium in the periodic table metallurgists also highlight. The element serves as a ligature when casting steels. Previously, sulfur was added to them, but its metallic properties were not so pronounced. Selenium makes it finely crystalline, without pores. The possibility of casting defects is eliminated and the fluidity of steel increases.
Electronic formula of selenium- part of electronics. The element can be extracted, for example, from televisions. They contain the 34th metal in photocells and rectifiers alternating current. Its inherent asymmetric conductivity allows selenium to control it.
That is, the substance passes current only in a certain direction. The technology is as follows: selenium layer applied to an iron plate, cadmium sulfide is placed on top. Now the flow of electrons will go exclusively from the iron to the cadmium compound.
The semiconductor properties of element 34 are the reason that more than half of its reserves are used for the needs of the technical industry. The metal is also used as a catalyst in organic synthesis reactions. They are part of the photographic and copying industry.
The “heart” of the well-known Xerox machines - selenium drums. When exposed to light, they begin to conduct electricity, acquiring a positive charge. The original image is reflected and projected onto the drum. This is how copies are made.
The use of element 34 is limited by its toxicity. So, selenium oxide formula useful in -ion batteries. However, it is better not to bring the substance to the skin, as it will corrode the tissue. Although, doctors have adapted selenium to fight cancer.
Selenium extraction
Since selenium is mixed with sulfur, the element is extracted from ferrous sulfate. You don’t even need to do anything special for this. The 34th metal accumulates in dust cleaning chambers of sulfuric acid plants. Selenium is also taken from copper electrolysis plants.
It leaves behind anode sludge. It is from this that the 34th element is isolated. It is enough to treat the sludge with solutions of hydroxide and sulfur dioxide. The resulting selenium must be purified. For this purpose, the distillation method is used. Afterwards, the metal is dried.
Selenium price
Over the past 3 months selenium cost fell from 26 to 22 dollars per kilogram. This is data from the London Non-Ferrous Metals Exchange. Experts predict that the decline in prices will again be replaced by its growth. Outside of exchanges, metal is traded at a cost that depends on the modification of the element and its shape.
So, for a kilogram of gray granules they ask for 4,000-6,000 rubles. Technical, that is, powdery, bad purified selenium, you can buy around 200 rubles for 1,000 grams.
The price range also depends on the delivery distance and the volumes ordered. If selenium is included in medicines, a few grams can cost as much as a whole kilogram. What is important here is the complex effect of the drug, and not the cost of its parts.
Black metallic selenium crystals formed on a burning coal dump. Image width is 1.8 mm. Germany, North Rhine-Westphalia, Aachen, Alsdorf, Anna mine
A brittle, shiny, black non-metal (stable allotropic form, unstable form - cinnabar-red). Refers to chalcogens. It is part of the active centers of some proteins in the form of the amino acid selenocysteine. The human body contains 10-14 mg of selenium, most of it is concentrated in the liver, kidneys, spleen, heart, testicles and spermatic cords in men. Selenium is part of muscle tissue proteins and myocardial proteins.
See also:
There are two modifications of selenium:
1. Crystalline (monoclinic selenium a- and b-forms, hexagonal selenium g-form).
2. Amorphous (powdery, colloidal and glassy forms of selenium).
The amorphous red modification of selenium is one of the unstable modifications of the element. Powdered and colloidal forms of selenium are obtained by reducing the substance from a solution of selenous acid H 2 SeO 3.
Black glassy selenium can be obtained by heating an element of any modification to a temperature of 220 degrees Celsius with rapid cooling. Hexagonal selenium has grey colour. This modification, which is the most thermodynamically stable, can also be obtained by heating to the melting point with further cooling to a temperature of 180-210 degrees Celsius. It is necessary to maintain this temperature regime for some time.
The melting point of the substance is 217 (α-Se) and 170–180 degrees Celsius (β-Se), and it boils at a temperature of 685 0.
Oxidation states that selenium exhibits in reactions: (-2), (+2), (+4), (+6), it is resistant to air, oxygen, water, hydrochloric acid and dilute sulfuric acid.
It can be dissolved in high concentration nitric acid, “regia vodka”, and dissolves for a longer time in an alkaline environment with oxidation. Is diamagnetic.
Since selenium is mixed with sulfur, the element is extracted from ferrous sulfate. You don’t even need to do anything special for this. The 34th metal accumulates in dust cleaning chambers of sulfuric acid plants. Selenium is also taken from copper electrolysis plants. It leaves behind anode sludge. It is from this that the 34th element is isolated. It is enough to treat the sludge with solutions of sodium hydroxide and sulfur dioxide. The resulting selenium must be purified. For this purpose, the distillation method is used. Afterwards, the metal is dried.
Excellent glossy crystals from burning coal dumps. Image width is 1.8 mm. Germany, North Rhine-Westphalia, Aachen, Alsdorf, Anna mine
The selenium content in the earth's crust is about 500 mg/t. The main features of the geochemistry of selenium in the earth's crust are determined by the proximity of its ionic radius to the ionic radius of sulfur. Selenium forms 37 minerals, among which first of all should be noted ashavalite FeSe, clausthalite PbSe, timannite HgSe, guanajuatite Bi 2 (Se, S) 3, hastite CoSe 2, platinite PbBi 2 (S, Se) 3, associated with various sulfides , and sometimes also with cassiterite. Native selenium is occasionally found. Sulfide deposits are of major industrial importance for selenium. The selenium content in sulfides ranges from 7 to 110 g/t. Selenium concentration in sea water 4·10 -4 mg/l.
One of the most important areas of its technology, production and consumption is the semiconductor properties of both selenium itself and its numerous compounds (selenides), their alloys with other elements in which selenium began to play a key role. IN modern technology Selenides of many elements are used in semiconductors, for example, tin, lead, bismuth, antimony, and lanthanide selenides. The photoelectric and thermoelectric properties of both selenium itself and selenides are especially important.
The stable isotope selenium-74 made it possible to create a plasma laser with colossal amplification in the ultraviolet region (about a billion times). Radioactive isotope selenium-75 is used as powerful source gamma radiation for flaw detection.
Potassium selenide together with vanadium pentoxide is used in the thermochemical production of hydrogen and oxygen from water (selenium cycle). Semiconductor properties of selenium in pure form were widely used in the mid-20th century to make rectifiers, especially in military equipment for the following reasons: unlike germanium, silicon, selenium is insensitive to radiation, and, in addition, the selenium rectifier diode has the unique property of self-healing in the event of a breakdown: the breakdown site evaporates and does not lead to a short circuit, the permissible current of the diode is slightly reduced, but the product remains functional. The disadvantages of selenium rectifiers include their significant dimensions.
Selenium is used as a powerful anticancer agent, as well as for the prevention wide range diseases. According to studies, taking 200 mcg of selenium per day reduces the risk of rectal and colon cancer by 58%, prostate tumors by 63%, lung cancer by 46%, and reduces overall mortality from cancer by 39%.
Small concentrations of selenium suppress histamine and due to this have an antidystrophic effect and antiallergic effect. Selenium also stimulates tissue proliferation, improves the function of the gonads, heart, thyroid gland, and immune system.
In combination with iodine, selenium is used to treat iodine deficiency diseases and thyroid pathologies.
Selenium salts help restore low blood pressure with shock and collapse
Selenium - Se
Hey's CIM Ref1.53
| Strunz (8th edition) | 1/B.03-30 |
| Nickel-Strunz (10th edition) | 1.CC.10 |
| Dana (7th edition) | 1.3.3.1 |
| Dana (8th edition) | 1.3.4.1 |
Global trends are such that people are increasingly thinking about the state of their body and health in general. Research is being conducted and theories of the influence of certain chemical compounds on organs and systems are being proven. Selenium was no exception, since the benefits of this chemical element for living organisms are invaluable.
Selenium is one of the chemical elements present in periodic table D. I. Mendeleev. Refers to non-metals. Its atomic number is 34. Selenium minerals can be black, red or gray in color.
Natural selenium is found in the earth's crust. It got its name from the Greek word “Selene” (Moon). Found in mineral waters and sea water. Its properties are similar to sulfur, but its chemical activity is less.
Selenium is one of the elements necessary for life, as it is part of proteins. In proteins it is represented by the amino acid selenocysteine. Selenium deficiency (especially in children) is fatal.
In the human body, this element performs several functions:
Interesting fact
Selenium is also present in the nuclei of living cells. It promotes the metabolism of nucleic acids. A nucleic acids(DNA and RNA) are found in all living organisms and are responsible for the transmission of hereditary information.
For the human body, this element plays an invaluable role. But you should be careful with it, since its deficiency (as well as its excess) can lead to the death of a living organism. The recommended daily dose of the substance for normal human life is 70-100 mcg.
Why is this microelement so necessary for any organism?
On a note
Selenium is also extremely important for men's health: the microelement helps enhance reproductive function, significantly increasing the activity of male germ cells.
This element increases the activity of the immune system, which is extremely important in childhood. Selenium deficiency can lead to endemic cretinism and mental retardation. And in combination with the Coxsackie virus, which Lately spreads across to the globe, microelement deficiency can provoke Keshan disease. This pathology leads to degeneration of myocardial tissue with further necrosis. Without qualified help, it causes death.
Unfortunately, malignant neoplasms are increasingly affecting people in all corners of the planet. Cancer treatment is expensive and does not always lead to positive results. Taking certain substances helps reduce the risk of developing cancer. One of these substances is selenium.
This trace element helps reduce the risk of tumor development by almost 40%. It seems incredible, but a sufficient amount of selenium-rich foods in your diet will help prevent cancer. And selenium therapy during oncology can almost halve the mortality rate of patients.
Many developed countries have long adopted programs for the “selenization” of the population. The main objectives of such programs are aimed at preventing pathologies among residents. Research recent years show that the benefits of selenium in the process of such programs are obvious: the risk of developing oncology is significantly reduced, as well as pathologies of the cardiovascular and immune systems.
Despite positive traits Selenium, this microelement can cause enormous harm to the body. Doctors strongly recommend using it in doses so as not to cause excess.
Negative impact chemical substance on the skin is as follows.
All selenium compounds are toxic. Hydrogen selenide is especially dangerous in this regard. Gray, or metallic, selenium is the least dangerous, but even 1 gram of the substance ingested can cause poisoning. Symptoms: abdominal pain, nausea, vomiting, diarrhea. After some time, the symptoms go away.
For women, a sufficient amount of micronutrients in the diet plays an important role. It provides many vital processes:
Thanks to a sufficient amount of this microelement, the risk of developing uterine and mammary gland cancer is reduced. If oncology has begun, then the chemical element can successfully cure the tumor. Taking selenium reduces the risk of having to remove the uterus, which allows you to preserve reproductive function.
During pregnancy, the microelement is also very important. It helps to cope with many difficulties of bearing a child:
It is very important to consume enough selenium during breastfeeding. It ensures good health of the mother and good health of the child. But you should not choose vitamin complexes with increased content selenium - give preference to natural sources of this substance.
How does a substance deficiency manifest itself? Its deficiency can be understood by the following symptoms:
But the following symptoms indicate an overabundance of the substance:
To understand how much of a substance is contained in certain products, just look at the comparison table. It presents herbal products– record holders for selenium content.
| The product's name | Microelement content in mcg per 100 g of raw product |
|---|---|
| Bertholetia (Brazil nut) grains | 1500 |
| Dates | 400 |
| Oyster mushroom (mushrooms) | 130 |
| Coconut pulp | 70-100 |
| Sunflower seeds | 50 |
| Corn | 30 |
| Broccoli | 2,5 |
The following table shows animal foods rich in selenium.
To get the required amount of microelement, you should not stuff yourself with chemicals. It is enough to review your diet and enrich it with the necessary products. And resort to pharmaceutical products only as a last resort. Take care of your health!
