solventdiluent

Solvent diluent, commonly called a diluent, is a solvent or solvent blend used to lower the concentration of a solute, reduce viscosity, control boiling behavior, or facilitate processing in a formulation or chemical operation. It provides a medium in which solutes can be dissolved or suspended under practical handling conditions, while preserving the chemical identity of the solute.

Key properties for selecting a diluent include chemical compatibility with the solute and other formulation components, polarity, boiling point and vapor pressure, and miscibility with the intended solvent system. The choice also considers safety, regulatory limits, odor, and environmental impact. In many uses the diluent is chosen to be relatively inert and to promote phase separation or easy removal in downstream steps.

Applications span several industries. In solvent extraction, a non-polar hydrocarbon diluent such as kerosene or a related solvent is blended with an extractant to optimize solute transfer and phase disengagement. In paints and coatings, diluents such as mineral spirits, toluene, or xylene adjust viscosity and drying behavior. In pharmaceutical and cosmetic manufacturing, solvents act as diluents to prepare concentrated solutions or suspensions; the selection balances solubility, safety, and regulatory considerations.

Safety and environmental aspects are important. Many diluents are volatile organic compounds with flammable and toxic properties. Regulations address exposure limits, storage classifications, ventilation, and waste handling, as well as limits on volatile organic compound emissions and environmental discharge.

See also: solvent, diluent, solvent extraction.