Diammonium phosphate

Diammonium phosphate (DAP) is a chemical compound with the formula (NH₄)₂HPO₄. It is one of a series of water-soluble ammonium phosphate salts that can be produced when ammonia reacts with phosphoric acid. Diammonium phosphate is used as a fertilizer, fire retardant, yeast nutrient in winemaking and mead brewing, and as an additive in some brands of cigarettes. Additionally, it is used in the production of some textiles and in the metal finishing industry. As a fertilizer, it is particularly effective for use at the beginning of the growth season, when plants are developing their root systems.

Production

Diammonium phosphate is manufactured by the reaction of ammonia with phosphoric acid. The process involves the neutralization of phosphoric acid with ammonia under controlled conditions to form diammonium phosphate. The chemical reaction can be represented as: \[2 NH_3 + H_3PO_4 \rightarrow (NH_4)_2HPO_4\]

Properties

Diammonium phosphate is a white, crystalline powder. It is highly soluble in water, with its solubility increasing with temperature. The compound is relatively stable, but it can decompose when heated, releasing ammonia gas.

Uses

Fertilizer

Diammonium phosphate is a popular fertilizer because it provides crops with the essential nutrients phosphorus (P) and nitrogen (N). It is especially beneficial at the start of the growth season, promoting the development of roots, flowers, and fruits. The high phosphorus content is crucial for energy transfer within the plant, while nitrogen is essential for growth and green leaf development.

Fire Retardant

The compound is also used as a fire retardant in various materials. It works by lowering the combustion temperature of the material, reducing its flammability.

Yeast Nutrient

In winemaking and brewing, diammonium phosphate serves as a yeast nutrient, providing the nitrogen needed for yeast to thrive during fermentation.

Other Uses

Diammonium phosphate's other applications include its use in cigarettes as an additive to improve the burn rate and in textiles and metal finishing industries for its chemical properties.

Environmental Impact

While diammonium phosphate is beneficial for agricultural use, its overuse can lead to environmental issues such as eutrophication, where water bodies become overly enriched with minerals and nutrients, leading to excessive growth of algae and other aquatic plants. This can harm aquatic ecosystems by depleting oxygen levels in the water, affecting fish and other marine life.

Safety

Diammonium phosphate is generally considered safe for handling and use in various applications. However, exposure to large amounts of dust can irritate the nose, throat, and lungs. Proper safety measures, such as wearing protective equipment, should be taken when handling the compound in industrial settings.

See Also

• Ammonium nitrate
• Monopotassium phosphate
• Fertilizers
• Eutrophication