Disodium phosphate

Disodium phosphate (DSP), or sodium hydrogen phosphate, is an inorganic compound with the formula Na2HPO4. It is one of several sodium phosphates, which are primarily used in commercial applications. DSP is available in both anhydrous and hydrated forms, the most common of which are the dodecahydrate (Na2HPO4·12H2O) and heptahydrate (Na2HPO4·7H2O).

Properties

Disodium phosphate has a molar mass of 141.96 g/mol for the anhydrous form. It is highly soluble in water, forming an alkaline solution. The solubility varies with the temperature and the presence of other salts. In its hydrated forms, it contains a significant amount of water of crystallization.

Production

Disodium phosphate is produced by the neutralization of phosphoric acid with sodium carbonate or sodium hydroxide, resulting in the sodium phosphate and water. The specific reaction conditions, such as temperature and pH, determine the exact form of sodium phosphate produced.

Uses

Disodium phosphate has a wide range of uses in both food and industrial applications. In the food industry, it is used as an emulsifier, buffering agent, and sequestrant. It helps to maintain the texture and appearance of processed foods. It is also used in the production of powdered products, such as cheese powders and creamers, to prevent caking.

In industrial applications, DSP is used in the manufacture of detergents, ceramics, and glass. It also serves as a fire retardant, a corrosion inhibitor, and a textile processing agent. In water treatment, disodium phosphate is used to soften water by removing calcium ions.

Health and Safety

While disodium phosphate is generally recognized as safe (GRAS) by the Food and Drug Administration (FDA) when used in accordance with good manufacturing practices, excessive intake can lead to an imbalance of phosphate levels in the body, potentially causing harm to kidney function. Individuals with kidney disease or similar health conditions should avoid excessive consumption of foods containing phosphate additives.

Environmental Impact

The use of disodium phosphate in detergents and other cleaning agents has raised environmental concerns. Phosphates can contribute to eutrophication of water bodies, leading to algal blooms that deplete oxygen in water and harm aquatic life. As a result, the use of phosphates in detergents has been restricted or banned in some jurisdictions.

See Also

• Sodium phosphate
• Phosphoric acid
• Eutrophication
• Food additive

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