Description
Technical grade urea (CO(NH2)2), also known as carbamide, is an organic chemical compound with a wide range of industrial uses. It occurs in the form of white crystals or granules that are odorless or may have a slight ammonia odor. Urea is used in chemistry and construction materials, for example as a component of some adhesives and wood impregnation products. Its melting/freezing point is approximately 132.7 °C and its relative density is approximately 1.32 g/cm³ at 20 °C. It should be used with caution due to its mild irritating properties and flammability. In addition, depending on the value of the parameter defining the content of biuret, i.e. the organic condensation product of urea (HN(CONH2)2), urea solution may be classified as AdBlue. AdBlue refers to urea in a 32.5% aqueous solution, used in the automotive industry as a reducing agent to break down environmentally harmful nitrogen oxides in the SCR (Selective Catalytic Reduction) catalyst. In order for a urea solution to be classified as AdBlue, the biuret content must not exceed 0.6%.
Urea is a hydrolysable substance that occurs in the presence of urease. This process takes place in the urinary system of living organisms and is also important in medical diagnostics. Urea reacts with acids to form salts. In addition, it undergoes the biuret reaction: heating urea leads to the formation of biuret, which can then be used for chemical protein detection (biuret test). Urea is also used to produce perurea in a reaction with hydrogen peroxide, which is used in cosmetics and pharmaceuticals. Moreover, urea may react with formaldehyde, forming urea-formaldehyde resins, used as adhesives. In the presence of oxygen, it burns to form nitrogen oxide, carbon dioxide and water. In soil, urea is converted to ammonia and nitrate, which are used by plants as nutrients. In addition, it can be metabolized by Sporosarcina pasteurii, a genus of soil bacteria containing urease. In this reaction, urea reacts with water, producing ammonia and carbon dioxide. Then, bacterially induced calcite precipitation occurs: in the presence of calcium ions, calcite is formed. This process can be used to improve soil quality and to produce bricks that do not require firing.
