Title of article
Hydrofluoric acid; Hydrofluoric acid; CAS number: 7664-39-3
physicochemical property
Hydrofluoric acid is an aqueous solution of hydrogen fluoride gas, which is a colorless, transparent to yellowish fuming liquid. There is a pungent smell. The molecular formula is HF-H2O. The relative density is1.15 ~1.18. The boiling point is 1 12.2℃ (38.2% by weight). Common concentration in the market: about 47%. It is a weak acid.
Invasive pathway
It can be absorbed through skin, and hydrofluoric acid mist can be inhaled through respiratory tract.
Introduction to toxicology
It is strongly irritating and corrosive to the skin. Hydrogen ions in hydrofluoric acid can dehydrate and corrode human tissues, and fluorine is one of the most active nonmetallic elements. After the skin is in contact with hydrofluoric acid, fluoride ions continue to freely penetrate into deep tissues and dissolve cell membranes, resulting in liquefaction and necrosis of epidermis, dermis, subcutaneous tissue and even muscle layer. Fluorine ions can also interfere with the activity of enolase and inhibit the oxygen uptake ability of skin cells. It is estimated that people who ingest 1.5g hydrofluoric acid can die immediately. Inhalation of high concentration hydrofluoric acid mist can cause bronchitis and hemorrhagic pulmonary edema. Hydrofluoric acid can also be absorbed through the skin, leading to serious poisoning.
clinical picture
The degree of skin damage is related to hydrofluoric acid concentration, contact time, contact site and treatment method. The higher the concentration, the longer the contact time, the softer or denser the damaged tissue, and the faster and stronger the effect. Contact with hydrofluoric acid with a concentration of more than 30% often leads to immediate pain and skin lesions. When exposed to low concentrations, pain and skin burns usually occur after a few hours. Local skin lesions first appear erythema, then turn into white edema with redness, then turn into light blue-gray necrosis, and then cover with thick brown or black scab, and form ulcers after scabbing. Finger injury often turns into bulla, the deck is often involved at the same time, and the nail bed and nail circumference are red and swollen. In severe cases, the subungual blister forms and the nail bed is separated from the deck. High-concentration burns often show progressive necrosis and slow ulcer healing. If it is serious, it will involve local bones, especially phalanges. It is characterized by narrow interphalangeal joint, rough articular surface, uneven edge, cortical hyperplasia, narrow medullary cavity and even osteomyelitis. Hydrofluoric acid mist can cause skin itching and dermatitis. When the dose is large, it can also cause burns to the skin, gastrointestinal tract and respiratory mucosa. After the eyes are exposed to high concentration hydrofluoric acid, local severe pain quickly forms white pseudomembranous opacity, which may lead to corneal perforation if not treated in time. Fluorosis caused by hydrofluoric acid burn has attracted attention. The patient developed convulsions due to hypocalcemia, prolonged Q-T interval of electrocardiogram and ventricular fibrillation.
deal with
Immediately after skin contact, rinse thoroughly with plenty of flowing water for a long time, and dilute hydrofluoric acid as soon as possible. This is the most effective measure and the key to treatment. There are many neutralization methods after hydrofluoric acid combustion. The general principle is that some soluble calcium and magnesium salts combine with fluoride ions to form insoluble calcium fluoride or magnesium fluoride, thus deactivating fluoride ions. The field application of lime water soaking or wet compress is easy to popularize. Ammonia reacts with hydrofluoric acid to produce corrosive amine difluoride, so it is not suitable as a neutralizer. Soak or wet compress with hydrofluoric acid burn treatment solution (20 ml of 5% calcium chloride, 20 ml of 2% lidocaine and 5 mg of dexamethasone). Soak in magnesium matte saturated solution. Direct current penetration of calcium ions. With the action of direct current, sufficient calcium ions can be directly introduced into the parts to be treated, so as to improve the local medication effect. For burns of 1 ~ 3 days, 1 ~ 2 times a day for 20 ~ 30 minutes each time. The treatment time of severe cases can be extended as appropriate. Hydrofluoric acid splashes into eyes, immediately separate eyelids, and rinse continuously with plenty of clean water for about 15 minutes. 2 ~ 3 drops of local anesthetic eye drops can relieve pain. At the same time, send it to ophthalmology for diagnosis and treatment.
Reaction with hydrofluoric acid:
Summary: Silicon is chemically inactive.
(1) anhydrous hydrogen fluoride molecular formula: HF molecular weight: 20.0 1 physical and chemical properties: anhydrous hydrogen fluoride is a colorless and transparent liquid at low temperature, with a boiling point of 19.4℃, a melting point of -83.37℃ and a density of 1.008g/cm3 (25 It is easy to volatilize into smoke at room temperature and normal temperature. Its chemical properties are very active, it can react with alkali, metal, oxide and silicate, and it can be freely mixed with water to form hydrofluoric acid under certain conditions. It has a strong pungent smell and has a strong corrosive effect on the mucous membranes of eyes, ears, nose and throat, and has a serious corrosive effect on people's teeth and bones, making them calcified. Anhydrous hydrogen fluoride technical index index name index excellent Acura (a) Acura (b) hydrogen fluoride content% 99.95 99.87 moisture content% 0.03 0.06 fluosilicic acid content% 0.0 1.03 sulfur dioxide content% 0.007 0.0 15 nonvolatile acid 0. 0.005 0.03 (based on H2SO4)% Usage: Anhydrous hydrogen fluoride has been widely used in atomic energy, chemical industry, petroleum and other industries. It is a strong oxidant and a basic raw material for preparing common fluorine, various fluorine refrigerants, inorganic fluorides and various organic fluorides. It can be prepared into water hydrofluoric acid for various purposes, catalysts for manufacturing graphite and organic compounds, and glass etchants. (2) industrial hydrofluoric acid molecular formula: HF molecular weight: 20.0 1 physical and chemical properties: industrial hydrofluoric acid is an anhydrous clear aqueous solution with a hydrogen fluoride content of less than 60%, also called hydrous hydrofluoric acid. Volatile in an open container, with strong corrosiveness and toxicity, it has the general generality of acid and the particularity of chemical reaction with silicon dioxide, silicate and glass. Technical index name of industrial hydrofluoric acid -Acura (I) Hydrogen fluoride content% 40.0-55.50 fluosilicic acid content% 0.03 sulfuric acid% 0.03 iron% 0.008 Usage: mainly used for manufacturing organic or inorganic fluoride, desilication and purification of rare metals, stainless steel, picture tubes, high and low carbon graphite, boiler and pipeline cleaning, glass instrument calibration, rock stratum corrosive agent, etc.