What is Fluoride?

Fluoride refers to an organic or inorganic compound containing negative-valent fluorine. Like other halogens, fluorine generates a single negative anion (fluoride ion F). Fluorine can form binary compounds with all elements except He, Ne, and Ar. From the lethal toxin sarin to the pharmaceutical efavirenz, from the insoluble calcium fluoride to the highly reactive sulfur tetrafluoride, all belong to the category of fluoride.

Fluoride has important applications in modern technology. Hydrofluoric acid is the most important fluoride produced, and is mainly used in the production of fluorinated hydrocarbons and aluminum fluorides. In addition, hydrofluoric acid has many special applications, such as using it to dissolve glass.

Fluoride liquid

Methods for measuring fluoride include fluorine reagent colorimetry, alizarin sulfonate zirconium colorimetry, ion selective electrode method, ion chromatography, and the like. There are two methods for measuring the fluorine content in water by colorimetric method: discoloration and color enhancement. (Red integrator) was released and discolored, and the colorimetric measurement was performed. This method has a large measurement error; the fluorine reagent colorimetric method is a color increase reaction, the chromaticity is stable, and the method is sensitive.

Fluoride atmosphere

The gaseous fluoride in the atmosphere is mainly HF, and there may be a small amount of SiF ₄ and CF _{4. The} fluorine-containing dust is mainly cryolite (Na ₃ AlF ₆ ), fluorite (CaF ₂ ), and aluminum fluoride (AlF ₃ ). , Sodium fluoride (NaF) and apatite. Fluoride is a highly toxic substance that enters the human body from the respiratory tract, causing mucosal irritation, poisoning and other symptoms, and can affect the normal physiological functions of various tissues and organs, and also cause harm to plant growth and development.

The methods for measuring fluoride in the atmosphere include absorption spectrophotometry, filter membrane (or filter paper) sampling-fluoride ion selective electrode method, and the like.

Filter membrane sampling-fluoride ion selective electrode method: glass fiber filter membrane impregnated with dipotassium hydrogen phosphate solution or glass fiber filter membrane impregnated with sodium bicarbonate-glycerin solution, the gaseous fluoride in the atmosphere is absorbed and fixed, and the dust Fluoride is blocked on the filter at the same time. After sampling, the filter is leached with water or acid and then measured by the fluoride ion selective electrode method.

Fluoride in nature mainly comes from volcanic eruptions, high-fluorine hot springs, arid soils, weathered release of fluorine-containing rocks, and the burning of fossil fuels. These fluorides can be distributed in the air or dissolved in water. Fluoride in the air is mainly divided into gaseous and granular solids.

Fluoride gas is a series of dozens of gaseous compounds such as sulfur hexafluoride, trifluoromethane, and hexafluoroethane. ^[2]