What Is the Standard Specification for Urea?

Urea is a colorless, odorless solid that is widely used in the manufacturing of fertilizers, resins, plastics, and many other industrial and agricultural applications. The standard specification for urea is an important consideration for its quality, safety, and efficacy. In this article, we will explore the various parameters that define the standard specification for urea.

Chemical Formula and Molecular Weight:

The chemical formula of urea is CO(NH2)2, and its molecular weight is 60.06 g/mol. This information is important for ensuring the purity and identity of the urea sample.

Purity:

The purity of urea refers to the percentage of urea by weight in a given sample. The minimum purity requirement for urea is typically 98.5%, although it may vary depending on the intended use of the product. Impurities in urea can affect its performance, stability, and safety.

Nitrogen Content:

Urea is a primary source of nitrogen in fertilizer formulations. The nitrogen content of urea is expressed as a percentage by weight, and the standard specification for urea requires a minimum nitrogen content of 46.0%. This nitrogen content is used to calculate the fertilizer grade of urea.

 Urea

Biuret Content:

Biuret is a byproduct of urea manufacturing and is considered an impurity in urea fertilizer. The biuret content of urea is expressed as a percentage by weight, and the standard specification for urea requires a maximum biuret content of 1.0%. Biuret can cause plant injury, reduce fertilizer effectiveness, and increase the risk of environmental pollution.

Moisture Content:

The moisture content of urea is expressed as a percentage by weight, and the standard specification for urea requires a maximum moisture content of 0.5%. High moisture content can cause caking and clumping of urea granules, which can affect the accuracy of fertilizer application.

Particle Size:

The particle size of urea can affect its handling, storage, and application characteristics. The standard specification for urea requires that 90% of the particles in a given sample must pass through a 2.8 mm sieve and that 100% of the particles must pass through a 4.75 mm sieve.

Color:

The color of urea can vary depending on its purity and manufacturing process. The standard specification for urea requires that the color of urea be white or slightly colored.

Melting Point:

The melting point of urea is an important parameter for its handling and storage. The standard specification for urea requires a minimum melting point of 132.7°C.

PH:

The pH of urea can affect its stability and compatibility with other materials. The standard specification for urea requires a pH range of 7.5 to 8.5.

Free Ammonia Content:

Urea can hydrolyze in the presence of water to form free ammonia, which can be toxic to plants and animals. The standard specification for urea requires a maximum free ammonia content of 0.05%.

In addition to these parameters, there may be other specifications required for specific applications of urea. For example, the standard specification for urea used in animal feed may require additional parameters such as ash content, heavy metal content, and microbiological purity.

In conclusion, the standard specification for urea is an important consideration for its quality, safety, and efficacy. It defines the minimum requirements for purity, nitrogen content, biuret content, moisture content, particle size, color, melting point, pH, and free ammonia content. These parameters ensure that the urea product meets the desired standards for its intended use and helps to prevent environmental pollution.