Particles finer than 0.1 μm (10−7m) in water remain continuously in motion due to electrostatic charge (often negative) which causes them to repel each other.
[citation needed] Once their electrostatic charge is neutralized by the use of a coagulant chemical, the finer particles start to collide and agglomerate (collect together) under the influence of Van der Waals forces.
Flocculants are used in water treatment processes to improve the sedimentation or filterability of small particles.
In addition, many of these chemicals, under appropriate pH and other conditions such as temperature and salinity, react with water to form insoluble hydroxides which, upon precipitating, link together to form long chains or meshes, physically trapping small particles into the larger floc.
The most common liquid polyacrylamide is supplied as an emulsion with 10-40% actives and the rest is a non-aqueous carrier fluid, surfactants and latex.