Тринатрийфосфат

Описание

Trisodium phosphate (TSP) is an inorganic salt used as industrial detergents, metal treatment and in toilet floor cleaners. TSP is pure cleaning power. Used as a water softener; for the treatment of boiler water; as a paint remover; in photographic developers; for tanning leather; for manufacturing paper; for clarifying sugar.
Also, it is a common laboratory reagent. Use to dissolve dirt, grease, and mildew from siding, decks, masonry, boats, campers. To prepare surfaces before painting or staining wash with TSP. Trisodium phosphate is an approved food additive in the U.S., European Union and other countries of the world. It may be added to foods and beverages or smoothies and green drinks. The primary function of trisodium phosphate is acidity regulation. It is commonly present in dry, extruded cereals. Together with other phosphates, it modifies cereal color, aids the cereal's flow through the extruder and provides phosphorus fortification. It is also commonly present in cheese sauces as an emulsifier. Trisodium phosphate is a strong chemical and can cause severe eye damage and can burn unprotected skin. Poisoning occurs if you swallow, breathe in, or spill large amounts of this substance on your skin.

Химические свойства

Trisodium phosphate (anhydrous) is a white, granular or crystalline solid, highly soluble in water and produces a strong alkaline solution. On exposure to heat, trisodium phosphate decomposes and produces toxic and corrosive fumes including phosphorous oxides.
The major use for trisodium phosphate is as a cleaning agent, food additive, stain remover, and degreaser. Trisodium phosphate of commercial grade is often partially hydrated and ranges from anhydrous trisodium phosphate, Na3PO4, to the dodecahydrate, Na3PO4 · 12H2O. Most often found in white powder form, it is also called trisodium orthophosphate or just plain sodium phosphate. Trisodium phosphate reacts violently with water and acids to liberate heat. Trisodium phosphate is corrosive and in the presence of water attacks many metals.
Trisodium phosphate is an approved flux for use in hard soldering joints in medical grade copper plumbing. The flux is applied as a concentrated water solution and dissolves copper oxides at the temperature used in copper brazing. Residues are fully water soluble and can be rinsed out of plumbing before it is put in service. Also, trisodium phosphate is still in vast use for the cleaning, degreasing, and deglossing of walls prior to painting. In fact, application of trisodium phosphate breaks the gloss of oil-based paints and opens the pores of latex-based paint providing a surface better suited for the adhesion of the subsequent layer of paint.

Физические свойства

The dodecahydrate is a white or colorless hexagonal crystal; density 1.62 g/cm3; melts around 75°C on rapid heating; partially loses water of crystallization at 100°C; retains the last water molecule even at moderate ignition; soluble in water, about 28 g/100 mL at 20°C; the solution is strongly alkaline; the pH of a 0.1M solution 11.5; insoluble in alcohol.

Использование

Trisodium phosphate (TSP) is a cleaning agent, lubricant, food additive, stain remover and degreaser. It is an alkaline cleaning agent that has been used as a household cleaner for many years, but ecological problems have largely ended that practice, at least in the western world. Substitutes are not as effective, but the raw chemical can be bought in bulk to add to other detergents. It works by disrupting the bacterial cell membrane and causing the contents to leak out, though the exact mechanism is not fully elucidated (Oyarzabal, 2005). Trisodium phosphate solutions are approved for treatment of beef carcasses in the US Code of Federal Regulations (21 CFR 182.1778; FDA 2003).
By the end of the 20th century, many products that formerly contained TSP were manufactured with TSP substitutes, which consist mainly of sodium carbonate along with various admixtures of nonionic surfactants and a limited percentage of sodium phosphates. TSP is commonly used after cleaning with mineral spirits in order to remove hydrocarbon residues. TSP may be used with household chlorine bleach in the same solution without hazardous reactions. This mixture is particularly good for removing mildew, but is ineffective at permanently removing mold.

Подготовка

Trisodium phosphate may be prepared in two steps, first by adding a little excess of sodium carbonate to phosphoric acid and then boiling the solution to expel carbon dioxide. Sodium hydroxide is then added to the solution:
Na2CO3+ H3PO4→Na2HPO4+ CO2+ H2O
Na2HPO4+ NaOH →Na3PO4+ H2O
Alternatively, trisodium phosphate may be prepared by complete neutralization of phosphoric acid with sodium hydroxide, followed by evaporation and crystallization:
H3PO4+ 3NaOH →Na3PO4+ 3H2O

Общее описание

Sodium phosphate is a colorless to white crystalline powder or granules. It is prepared by neutralization of phosphoric acid under controlled conditions with sodium hydroxide or sodium carbonate .

Опасность

Toxic by ingestion, irritant to tissue.

Промышленное использование

Different salts of phosphoric and polyphosphoric acids are used in flotation. From this fairly large family of reagents, sodium phosphate is the preferred species. Trisodium phosphate is a white, crystalline substance highly soluble in water. Neutralizing phosphoric acid with soda ash produces trisodium phosphate.
Mono- and disodium phosphates are rarely used.

Механизм действия

TSP is a tribasic orthophosphate with a pH of 10.0–12.0 in aqueous solution, and overall alkalinity aids in its interaction with cell membrane lipids, resulting in membrane leakage . TSP may also increase the sensitivity of some microorganisms to nisin and lysozyme.

Профиль безопасности

Moderately toxic by intravenous route. Mutation data reported. A strong, caustic material. When heated to decomposition it emits toxic fumes of Na2O and POx. See also PHOSPHATES.