PM2.5 is not a colloid, because a colloid is a more homogeneous mixture, in the colloid contains two different states of matter, a dispersed phase, another continuous phase. Part of the dispersed mass is composed of tiny particles or droplets, dispersed mass particle diameter between 1~100nm dispersion system is colloidal, and PM2.5 dispersed mass particle diameter between 1~2500nm.
Colloid is a kind of dispersant particle diameter between the coarse dispersion system and the solution of a class of dispersion system, which is a highly dispersed multi-phase inhomogeneous system.
In wastewater treatment can also be applied to the knowledge of colloids, some of the pollutants in the wastewater is in the form of colloids, so a lot of wastewater treatment equipment aims to study how to quickly and efficiently remove the pollutants in the wastewater in the form of colloids. Colloids are not always gels or liquids. For example, iron hydroxide colloids, clouds, fog, etc..
Extended information
Colloid applications:
1, agricultural production: the soil's role in retaining fertilizer . Many substances in the soil, such as clay humus, often in the form of colloids.
2, health care: hemodialysis, serum paper electrophoresis using electrophoresis to separate various amino acids and proteins. Medicine is increasingly using highly dispersed colloids to test or treat diseases, such as colloidal magnetic fluid cancer treatment is made of magnetic substances into colloidal particles, as a carrier of drugs, under the action of the magnetic field will be sent to the focal point of the disease, thus improving the efficacy of treatment.
3, daily life: the principle of making tofu, soymilk, milk and porridge (colloidal aggregation and sinking), alum water purification.
4, natural geography: the formation of deltas at the mouth of the river, the principle of its formation is the electrolyte in the sea water to make the river sediment colloid polymerization.
5, industrial production: the production of colored glass (solid solution). In metals, ceramics, polymers and other materials to add solid colloidal particles, not only can improve the impact strength of the material, fracture resistance, tensile strength and other mechanical properties, but also improve the optical properties of the material.
Baidu Encyclopedia - Colloids