Ureawater

Ureawater is an aqueous solution of urea (carbamide) in water. Urea is a nitrogen-rich organic compound used in agriculture, industry, and automotive emissions control. In solution, urea is highly soluble in water, producing clear, non-volatile mixtures with properties that depend on concentration and temperature.

Concentrations of ureawater vary by application. Dilute solutions used for fertigation or foliar sprays often contain tens of grams of urea per liter, while commercial diesel exhaust fluid (DEF), also called AdBlue, is a standardized 32.5% by weight urea solution in demineralized water. DEF typically has a density around 1.08–1.09 g/mL and freezes at about −11°C, requiring heated or insulated storage in cold climates.

Production of ureawater generally involves dissolving solid urea in water under agitation, with additional purification or deionization as required by the intended use. For DEF/AdBlue, the solution must meet specific purity standards (such as ISO 22241) to prevent catalyst poisoning and equipment deposits.

Applications include agriculture and horticulture, where ureawater serves as a nitrogen source for crops, as well as hydroponics and fertigation systems. In industry, ureawater can be a feedstock or intermediate in chemical processes. In automotive contexts, a concentrated ureawater solution (DEF) is injected into exhaust streams to promote NOx reduction via selective catalytic reduction.

Handling and safety considerations are generally modest, but high-concentration solutions can irritate skin and eyes. Environmental concerns include nitrogen release when ureawater enters waterways, which can contribute to eutrophication if misused or improperly discharged. Storage requires clean, corrosion-resistant containers, protection from contamination, and temperature controls appropriate to the solution’s formulation.