fosfát

Fosfát, or phosphate, is a chemical species with the formula PO4^3−. It forms a wide range of salts and esters and is central to biology, agriculture, and industry. Inorganic phosphate exists mainly as orthophosphate (PO4^3−), dihydrogen phosphate (H2PO4−), and hydrogen phosphate (HPO4^2−), with the relative proportions determined by pH.

In aqueous solution, phosphoric acid (H3PO4) dissociates in three steps, giving pKa values around 2.15, 7.20, and 12.35. This buffering behavior means phosphate acts as a pH buffer in natural waters and biological systems. Phosphate is essential for life: it is a component of nucleic acids (DNA and RNA), ATP and other energy carriers, phospholipids, and many metabolites. It also participates in cellular signaling through phosphorylation and dephosphorylation reactions.

Geologically and industrially, phosphates are found in minerals such as apatite. The principal industrial use is in fertilizers. Phosphate rock is processed to produce phosphoric acid, which is then converted into various phosphate salts, including mono-, di-, and triple superphosphates, for agricultural application. Organic phosphates, or phosphate esters, are common in chemistry and biochemistry, including sugars and nucleotides linking through phosphate groups.

Environmental considerations are significant. Runoff and leaching of phosphates from agricultural land and wastewater can cause eutrophication, leading to algal blooms and hypoxic waters. Wastewater treatment and regulations in many regions aim to reduce phosphate discharges. Phosphate additives also appear in food processing and cleaning products, where regulatory limits may apply to minimize environmental impact.