Urea – applications, properties and significance in industry

Urea is an organic chemical compound  with the formula CO(NH2)2 which plays a key role in many industries and medicine. Derived from the ornithine cycle, where it is a product of ammonia conversion, it is an essential metabolite in living organisms. No wonder it is now widely used and significant in many sectors of industry and in cosmetic products.

Published: 22-01-2025

What  is  urea  and  what  are  its  properties?

Urea (also called carbamide) is a non-flammable, crystalline substance, usually  white or colorless, with a slightly ammoniacal odor and  a  saltish  taste. It is a hygroscopic substance, which means that it easily absorbs moisture from the environment, and also dissolves very well in water. During long-term storage in aqueous solutions, urea can decompose, producing ammonia and carbon dioxide.

Technical urea  is used in many  industries. It  is used as a component  of fertilizers and an additive  to animal  feed. It also serves as a raw  material in the  production of plastics, fireproof impregnants and adhesives.

In animal  experiments, urea has shown low toxicity,  both  acute and chronic,  and no carcinogenic effects or adverse effects  on reproductive capabilities. There is no harmonized classification  of  urea  toxicity  in  the  European  Union. This substance  is characterized by very low vapor pressure, which means that exposure to it occurs mainly through inhalation of  dusts. In  order  to  protect workers  from  potential problems related  to the  presence  of  urea  dust  in  the  air,  it  has been  proposed  to  establish  a maximum allowable concentration (MAC) of 10 mg/m^3. This value is consistent  with  standards for  other  dusts  that  are  not  classified  as toxic,  but  may  pose  a risk  due  to  reduced visibility.

In  addition:  

  • Urea is a hygroscopic  solid that  dissolves well in water,  methanol, ethanol, glycerol,  dimethyl sulfoxide  (DMSO), acetic acid and concentrated hydrochloric acid.
  • In aqueous solutions,  it undergoes  slow hydrolysis,  during  which ammonia  and carbon  dioxide  are formed. The hydrolysis  process can be accelerated by heating  and  the  addition  of  acids  or  bases.
  • Urea is characterized by very poor  solubility in benzene and chloroform, and it dissolves  poorly  in  ethyl  ether.
  • Urea can react with  some substances, forming products with  strong  explosive properties  (e.g.  in  the  case  of  reactions  with  sodium  or  calcium  chlorates(I)).

The process of urea production — from raw material to final product

#1. Ammonia synthesis

Urea production begins  with  ammonia  synthesis,  mainly  in the Haber-Bosch process. This process involves the reaction of nitrogen (N2) with hydrogen (H2), which are mainly sourced from natural  gas. High pressure  and temperature (approx.  450°C and 200 atm) and the presence of an iron-based catalyst enable this exothermic reaction to take place.

#2. Urea synthesis  

The next  stage is the reaction  of ammonia  with  carbon  dioxide  (CO2) to produce  urea. This process takes place in two main stages. The first is the formation of ammonium carbamate,  and the second is the decomposition of ammonium carbamate.  Ammonium carbamate  is then  converted  into  urea  and  water  under  high  pressure  (150-250 atm) and temperature (180-190°C).

#3.  Condensation  and  crystallization

The resulting urea  solution is then  concentrated by  evaporating water  in  a  vacuum evaporator. This process results in urea in the form of a  concentrated solution.

#4.  Granule  formation  

The concentrated urea solution is cooled and then granulated in special drum or plate granulators, where,  under  the influence  of movement and additional cooling, urea crystallizes, forming granules.

The urea granules are then dried in drum dryers to remove excess moisture and then cooled in coolers. This process ensures the stability  of the granules and optimizes their physical properties.

#5. Packaging and storage

Finally, the finished urea is packed into bags or transported directly to storage tanks, from where it is distributed to end customers.

A woman holding a test tube with urea, with plants in a greenhouse in the background

The importance of urea in industrial sectors

In the selective catalytic  reduction (SCR), urea helps to reduce  nitrogen oxide emissions  from stationary and mobile sources. In the  pharmaceutical and cosmetic industries and in household chemicals, urea is valued as a component of many preparations. It is also used for  de-icing roads, railway tracks and runways, and in the food industry it is added to bakery products,  alcoholic beverages and gelatine products.

Urea in agriculture

Thanks to its high nitrogen content (around 46%), urea is used in fertilization programs, supporting  intensive  plant  growth. Currently,  it is used in the form  of granules or solutions, where it quickly  hydrolyzes  to ammonia  and carbon  dioxide,  releasing  nitrogen available for plants. However,  what  is important – due to the high  volatility of ammonia,  it is necessary to quickly incorporate urea into the soil after application to minimize nitrogen losses.

Find out more: https://www.products.pcc.eu/en/blog/what-are-organic-fertilisers-and-what-should-we-know-about-them/

Urea in cosmetics

Urea is one of the most effective moisturizing ingredients  used in the cosmetic industry. It is a component of the natural moisturizing factor (NMF) found in keratinocytes, which is crucial for maintaining the appropriate level of hydration of the stratum corneum of the epidermis (the so-called humectant). The effectiveness of urea in cosmetics depends on its concentration: in low doses it acts mainly  as a moisturizer, while in higher concentrations it has keratolytic properties. Interestingly, its derivatives are also used, such as allantoin which promotes the regeneration of the epidermis.[2]

Find out more : https://www.products.pcc.eu/en/blog/cosmetic-ingredients/  and  on https://www.products.pcc.eu/en/inci-names/

Urea in the pharmaceutical industry

In pharmacy, urea is used as an osmotic agent in diuretics and as an ingredient of creams and ointments for treating dermatological conditions, such as psoriasis, eczema. Learn more at:

https://www.products.pcc.eu/en/k/pharmaceutical-industry/

Urea in the textile industry

Interestingly, urea is also used as a dye additive. Thanks to its chemical properties, it improves the solubility and stability  of dyes, which is crucial in the production of highly  intensive  colors. Urea is also used in the production of certain types of artificial fabrics  and as a softening component.

Urea in the chemical industry

Urea plays the role of a raw material in the production of many chemical products, including the production of urea-formaldehyde resins, which are widely used as adhesives in the wood and furniture industry. These resins they are characterized by exceptional durability and resistance to moisture, thanks to which they are used in production chipboard and plywood.

Warehouse with chemicals

The impact of urea on the environment – challenges and solutions

Challenge #1: Eutrophication of surface waters

Excessive use of urea in agriculture can lead to the leaching of excess nitrogen into rivers  and lakes. This, in turn, can cause eutrophication, i.e. excessive growth of algae and other aquatic plants, which disrupts the balance of ecosystems and reduces the oxygen level in the water.

In the face of this challenge, it is crucial to introduce nutrient management practices, i.e. the use of GPS technology to control optimal doses.

Challenge #2: Emissions of greenhouse gases

The hydrolysis of urea in the soil leads to the production of ammonia, which can be converted into nitrogen oxides (NOx) – potent greenhouse gases. NOx emissions contribute to global warming and air quality  problems, which is why it is necessary to implement technologies to reduce ammonia and NOx emissions in agriculture, such as optimizing soil pH and using urease inhibitors which slow down the decomposition of urea.

Sources:
  1. SKOWROŃ, J. Mocznik–frakcja wdychalna.
  2. Kapuścińska, A., & Nowak, I. (2014). Wykorzystanie mocznika i jego pochodnych w przemyśle kosmetycznym. Chemik, 68(2), 91-96.

Comments
Join the discussion
There are no comments
Assess the usefulness of information
- (none)
Your rating