Urea (Latin: Urea) is not a plant but a chemical compound with the molecular formula CH4N2O. It is a colorless, crystalline powder that is easily soluble in water. Urea is a natural component of the urine of mammals and is used by them to excrete nitrogen. However, in the industry, urea is synthesized artificially.
The production of synthetic urea dates back to 1828 when the German chemist Friedrich Wöhler first synthesized urea from inorganic materials. The modern industrial production of urea is based on the Haber-Bosch process, in which ammonia and carbon dioxide react under high pressure and temperature to form urea. The largest urea producers are located in Asia, North America, and Europe.
Urea is produced on an industrial scale by the aforementioned Haber-Bosch process. Ammonia (NH3) and carbon dioxide (CO2) react in a reactor under high pressure (approximately 150-300 bar) and high temperature (approximately 160-210°C) to form urea. The quality of the urea depends on the purity of the raw materials and the process conditions. After the reaction, the urea is purified by crystallization and drying and is brought into granular or prill form to facilitate transport and storage.
Urea has a wide range of applications in various industries. Here are some of the most important applications:
a) Agriculture: Urea is an important component of fertilizers and provides nitrogen for plant growth. The granular form of urea allows for even distribution on agricultural land. The nitrogen in urea is converted by microorganisms in the soil into ammonium and nitrate, which can be absorbed by plants. Approximately 50% of the urea produced worldwide is used as fertilizer.
b) Cosmetics: Urea in cosmetics
In the cosmetics industry, urea plays a significant role as a moisturizer, keratolytic, and skin-soothing agent. The following sections describe the applications and benefits of urea in cosmetic products as well as possible side effects and limitations.
Moisturizer: Urea is an excellent moisturizer for the skin because it is hygroscopic - that means it attracts water from the environment and binds it to itself. Urea increases the water-binding capacity of the skin by binding water in the upper layers of the skin, thus increasing the moisture content of the skin. This improves the suppleness, elasticity, and overall condition of the skin. Urea is commonly used in creams, lotions, and serums for dry, sensitive, or mature skin.
Keratolytic agent: Urea acts as a keratolytic agent by promoting the shedding of dead skin cells, resulting in a smoother and fresher skin surface. Urea can also enhance the penetration of other cosmetic active ingredients into the skin by reducing the skin's barrier function. Due to these properties, urea is used in peeling products, anti-aging creams, and acne treatments.
Skin-soothing agent: Urea has anti-inflammatory and anti-itch properties that help to reduce skin irritations and redness. It can also strengthen the skin barrier by promoting the production of ceramides and other lipids that protect the skin from external influences and moisture loss. Due to these benefits, urea is used in products for the treatment of skin conditions such as atopic dermatitis, psoriasis, and ichthyosis.
Safety and side effects: Urea is generally safe and well-tolerated, but may cause skin irritation or allergic reactions in some individuals, particularly at higher concentrations. Individuals with sensitive skin should initially try products with lower concentrations of urea (1-5%) and discontinue use in case of intolerance or irritation. In medical skin care products, urea concentrations of up to 40% can be used. In these cases, application should be conducted under medical supervision.
Overall, urea offers a variety of benefits for skin care and is a valuable ingredient in many cosmetic products. However, it is important to choose the appropriate concentration and application to achieve the best results.
c) Chemical industry: Urea serves as a starting material for the production of urea-formaldehyde resins, which are used in the production of particleboard, fiberboard, and synthetic resin adhesives. Additionally, urea is used in the production of melamine, a plastic used for dishes, countertops, and laminate flooring.
d) Automotive industry: Urea is used in the exhaust gas cleaning of diesel vehicles. An aqueous urea solution (AdBlue) is injected into the exhaust system to convert nitrogen oxides into harmless nitrogen and water. This technology, known as selective catalytic reduction (SCR), helps to reduce emissions from diesel vehicles and comply with environmental regulations.
e) Medicine: Urea is used in medicine as an osmotic diuretic for the treatment of edema and increased intracranial pressure. However, it is important to adhere to the proper dosage to avoid unwanted side effects. Urea can also be used in the treatment of urinary stones by reducing the formation of uric acid crystals.
f) Textile industry: In the textile industry, urea is used as a softener and humectant to improve the elasticity and suppleness of fibers. It is also used in the production of dyes and textile finishes to increase the solubility of dyes and ensure uniform dyeing.
g) Animal feed: Urea can be used as a non-protein nitrogen source in animal feed, particularly for ruminants such as cattle and sheep. However, it is important to carefully control the urea content in feed to avoid overdosing and health problems in animals.
When using urea in agriculture, it is important to ensure that the proper amount is applied to minimize environmental pollution from nitrogen leaching into soil and water. Excessive use of urea fertilizer can lead to eutrophication of water bodies and a reduction in water quality. In cosmetic products, urea should only be used in appropriate concentrations to avoid skin irritations or allergic reactions.