The first information about compounds containing mercury reaches us from the depths of centuries. Aristotle mentions it for the first time in 350 BC, but archaeological finds indicate an earlier period of use. The main areas of use of mercury were medicine, painting and architecture, the manufacture of Venetian mirrors, metal processing, etc. People found out its properties only experimentally, which required a lot of time and cost many lives. The fact that mercury is dangerous to humans is known from the moment it began to be used. Modern research methods and methods are much more effective and safer, but people still do not know much about this metal.
Chemical element
Under normal conditions, mercury is a heavy white-silver liquid; its affiliation with metals was proved by M.V. Lomonosov and I.A. Brown in 1759. Scientists have proven that in a solid state of aggregation, it is electrically conductive and can be forged. Mercury (Hydrargyrum, Hg) in the periodic system of D. I. Mendeleev has an atomic number of 80, is located in the sixth period, group 2 and belongs to the zinc subgroup. Translated from Latin, the name literally means "silver water", from Old Russian - "roll". The uniqueness of the element lies in the fact that it is the only liquid metal that is found in nature in dispersed form and is found in the form of compounds. A drop of mercury rolling down a rock is an impossible phenomenon. The molar mass of the element is 200 g / mol, the radius of the atom is 157 pm.
The properties
At a temperature of 20 ° C, the specific gravity of mercury is 13.55 g / cm 3 , -39 ° C is required for the melting process, 357 ° C for boiling, and 38.89 ° C for freezing. An increased saturated vapor pressure gives a high evaporation rate . With increasing temperature, mercury vapors become the most dangerous for living organisms, and for this process, water or any other liquid is not an obstacle. The most popular property in practice is the production of amalgam, which is formed as a result of dissolution of the metal in mercury. With its large amount, the alloy is obtained in a semi-liquid state of aggregation. Mercury easily leaves the compound, which is used in the process of extracting precious metals from ore. Amalgamation is not amenable to metals such as tungsten, iron, molybdenum, vanadium. Chemically, mercury is a fairly stable element that easily goes into a native state and reacts with oxygen only at high temperatures (300 ° C). When interacting with acids, dissolution occurs only in nitric acid and aqua regia. Metallic mercury is oxidized by sulfur or potassium permanganate. It actively reacts with halogens (iodine, bromine, fluorine, chlorine) and non-metals (selenium, phosphorus, sulfur). Organic compounds with a carbon atom (alkyl-mercury) are the most stable and form under natural conditions. Methyl mercury is considered one of the most toxic organometallic compounds with a short chain of bonds. In this state, mercury is the highest danger to humans.
Being in nature
If we consider mercury as a mineral, which is used in many industries and spheres of human economic activity, then this is a rather rare metal. According to experts, the surface layer of the earth's crust contains only 0.02% of the total amount of the mentioned element. Most of the mercury and its compounds are in the waters of the oceans and scattered in the atmosphere. Recent studies show that a large content of this element contains the mantle of the Earth. In accordance with this statement, a concept such as “mercury respiration of the Earth” arose. It consists in the process of degassing during further evaporation from the surface. The largest mercury release occurs when volcanoes erupt. Subsequently, natural and man-made emissions are included in the cycle, which occurs due to the combination with other elements under favorable natural conditions. The process of formation and decomposition of mercury vapor is poorly studied, but the participation of some types of bacteria is considered the most likely hypothesis. But the main problem is methyl and demityl derivatives, which are actively formed in nature - in the atmosphere, water (bottom muddy areas or sectors of the highest pollution by organic substances) - without the participation of catalysts. Methyl mercury has a very high similarity with biological molecules. What is dangerous about mercury is the possibility of accumulation in any living organism due to the ease of penetration and adaptation.
Place of Birth
There are more than 100 mercury-containing and mercury minerals, but cinnabar is the main compound that ensures the profitability of production. In percentage terms, it has the following structure: sulfur 12-14%, mercury 86-88%, while native mercury, faded ores, metacinabarite, etc. are associated with the main sulfide mineral. The sizes of cinnabar crystals reach 3-5 cm (maximum), the most common are 0.1-0.3 mm in size and may contain impurities of zinc, silver, arsenic, etc. (up to 20 elements). There are about 500 ore deposits in the world; the most productive deposits are in Spain, Slovenia, Italy, and Kyrgyzstan. For ore processing, two main methods are used: oxidation at high temperature with the release of mercury and enrichment of the initial material with subsequent processing of the resulting concentrate.
Areas of use
Due to the fact that the danger of mercury has been proven, its use in medicine has been limited since the 70s of the XX century. An exception is merthiolate, used for preserving vaccines. Silver amalgam is still found in dentistry today, but is actively replaced by reflective fillings. The most widespread use of hazardous metal is recorded in the creation of instruments and precision tools. Mercury vapor is used to operate fluorescent and quartz lamps. In this case, the result of exposure depends on the coating of the light transmitting body. Due to the unique heat capacity, metallic mercury is in demand in the production of high-precision measuring instruments - thermometers. Alloys are used for the manufacture of position sensors, bearings, sealed switches, electric drives, valves, etc. Biocidal paints previously also contained mercury and were used to cover the hulls of the vessel, which prevented them from fouling. The chemical industry in large quantities uses salts of this element as a catalyst for the release of acetaldehyde. In the agro-industrial complex, sublimate and calomel are used to process the seed stock - toxic mercury protects grain and seeds from pests. In metallurgy, amalgams are most in demand. Mercury compounds are often used as an electrolytic catalyst for the production of chlorine, alkali and active metals. Gold miners use this chemical element to process ore. Mercury and its compounds are used in jewelry, in the manufacture of mirrors and in the recycling of aluminum.
Toxicity (why mercury is dangerous)
As a result of human activities in our environment, the concentration of toxic substances and pollutants increases. One of these elements, designated in the first positions by toxicity, is mercury. Danger to humans are its organic and inorganic compounds and vapors. This is a cumulative highly toxic poison that can accumulate in the human body for years or come at a time. The central nervous system, the enzymatic and hematopoietic systems are affected, and the degree and outcome of poisoning depends on the dose and method of penetration, toxicity of the compound, exposure time. Chronic mercury poisoning (accumulation of a critical mass of a substance in the body) is characterized by the presence of an asthenovegetative syndrome, a violation of the nervous system. The first signs are: trembling of the eyelids, fingertips, and then the limbs, tongue and the whole body. With the further development of poisoning, insomnia, headaches, nausea, a violation of the digestive tract, neurasthenia are manifested, memory is impaired. If mercury vapor poisoning occurs, then respiratory tract diseases are characteristic symptoms. With the continuous exposure to the poisonous substance, the excretory system fails, which can lead to death.
Mercury salt poisoning
The fastest and most difficult process. Symptoms: headache, metallic taste, bleeding gums, stomatitis, increased urination with its gradual reduction and complete cessation. In severe form, damage to the kidneys, gastrointestinal tract, and liver is characteristic. If a person survives, then he will forever remain disabled. The action of mercury leads to the deposition of proteins and hemolysis of blood red blood cells. Against the background of these symptoms, an irreversible lesion of the central nervous system takes place. Such an element as mercury is a danger to humans in any form of interaction, and the consequences of poisoning can be irreparable: exerting an effect on the whole organism, they can affect the next generations.
Venom Penetration Methods
The main sources of poisoning are air, water, food. Mercury can enter through the respiratory tract when the substance evaporates from the surface. The skin and the gastrointestinal tract have good throughput. For poisoning, it is enough to swim in a body of water that is contaminated with industrial discharges containing mercury; to eat foods with a high content of a chemical element that can get into them from infected biological species (fish, meat). Mercury vapor poisoning is received, as a rule, as a result of professional activity - in case of non-observance of safety measures in the industries associated with this element. Poisoning in the domestic environment is no exception. This occurs during improper use of instruments and tools containing mercury and its compounds.
The danger of mercury from a thermometer
The most commonly used high-precision medical instrument is a thermometer, which is available in every home. Under normal living conditions, most people do not have access to highly toxic compounds that include mercury. “Smashed thermometer” - this is the most likely situation of interaction with the poison. Most of our compatriots still use mercury thermometers. This is primarily due to the accuracy of their testimonies and the distrust of the population in new technologies. If the thermometer is damaged, mercury is a danger to humans, of course, but illiteracy is even more dangerous. If you quickly, efficiently and effectively carry out a series of simple manipulations, then if harm is done to the health, then the minimum
.
Stage 1
First of all, it is necessary to collect all parts of the broken thermometer and mercury. This is the most time-consuming process, but the health of all family members and pets depends on its implementation. For proper disposal, it is necessary to take a glass vessel, which must be tightly closed. Before starting work, all tenants are removed from the premises, it is best to go outside or to another room where there is the possibility of constant ventilation. The process of collecting drops of mercury cannot be carried out using a vacuum cleaner or a broom. The latter can crush larger fractions of the metal and provide a large area of their distribution. When working with a vacuum cleaner, the danger lies in the process of heating the engine during operation, and the influence of temperature will accelerate the evaporation of particles, and this household appliance can not be used after that, it will only be disposed of.
Sequencing
- Wear disposable rubber gloves, a medical mask, shoe covers or plastic bags on shoes.
- Carefully inspect the place where the thermometer was broken; if there is a chance of mercury getting on textiles, clothing, carpets, they are hermetically packed in a garbage bag and disposed of.
- Glass parts are collected in prepared containers.
- Large drops of mercury are collected from a floor surface using a sheet of paper, a needle or knitting needles.
- Armed with a flashlight or enhancing the illumination of a room, it is necessary to expand the search for smaller particles (due to the color of the metal it is easy to find).
- Carefully inspect the floor cracks, joints of the parquet, plinth to exclude the possible ingress of smaller drops.
- In hard-to-reach places, mercury is collected by a syringe, which is then subject to disposal.
- Small drops of metal can be collected with adhesive tape, adhesive.
- During the entire time of work, it is necessary to go to a ventilated room or to the street every 20 minutes.
- All items and improvised items used in the collection of mercury must be disposed of with the contents of the thermometer.
Stage 2
After thorough mechanical assembly, it is necessary to chemically treat the room. You can use potassium permanganate (potassium permanganate) - a solution of high concentration (dark color) in the amount necessary for the treated area. Be sure to wear new rubber gloves and a mask. All surfaces are treated with the resulting solution using rags, and the existing recesses, cracks, cracks and joints are best filled with the solution. For the next 10 hours, it is better to leave the surface intact. After the specified time, the solution of potassium permanganate is washed off with clean water, then cleaning is carried out using detergents in the whole apartment. The next 6-7 days, it is imperative to regularly air the premises and daily wet cleaning. To make sure mercury is not available, you can invite specialists with special equipment from epidemiology centers.
Methods of treatment of intoxication
WHO identifies the 8 most hazardous substances whose contents in the atmosphere, food and water should be carefully monitored, due to their danger to human life and health. These are lead, cadmium, arsenic, tin, iron, copper, zinc and, of course, mercury. The hazard class of these elements is very high, and the consequences of poisoning by them cannot be completely stopped. The basis of treatment is to protect a person from further contact with poison. In mild and non-chronic cases of mercury poisoning, it is excreted from the body with feces, urine, sweat. The toxic dose is 0.4 ml, the lethal - from 100 mg. If you suspect an interaction with poison, you should contact a specialist who, based on the results of the tests, will determine the degree of intoxication and prescribe therapy.