of all, you may be wondering two things...what is sodium hexametaphosphate?
And just what is a dispersing agent?
start, sodium hexametaphosphate (SHMP) is a hexamer of composition (NaPO3)6.Sodium
hexametaphosphate of commerce is typically a mixture of polymeric metaphosphates,
of which the hexamer is one, and is usually the compound referred to by
this name. It is more correctly termed sodium polymetaphosphate. It is
prepared by melting monosodium orthophosphate, followed by rapid cooling.
hexametaphosphate (SHMP) is used as a sequestrant and has applications
in a wide variety of industries, including as a food additive in which
it is used under the E number E452i. Sodium carbonate is sometimes added
to SHMP to raise the pH to 8.0-8.6, which produces a number of SHMP products
used for water softening and detergents. Also used as a dispersing agent
to break down clay and other soil types.
is a dispersing agent, or deffloculating agent? A dispersing agent prevents
flocculation, or the combining of suspended matter into aggregates large
enough for gravity to accelerate their settling out.
and trivalent cations such as sodium hexametaphosphate are used in water
solutions to facilitate flocculation of insoluble particles in suspension,
especially colloidal size particles like clay and organic matter that
have negative surface charges. Addition of divalent or trivalent cations
is frequently used in water treatment to remove a combination of inorganic
and organic matter as well as living microscopic organisms through flocculation
followed by filtration.
agents such as sodium hexametaphosphate are more commonly used in laboratory
procedures to sustain suspensions and estimate particle size distribution.
They are commonly used as a component of detergents, for keeping pigments
dispersed in paints and in photography where they find special applications
to prevent spotting of films and photographs. While you can't see it SHMP
is hiding just beyond the shadows of your drinking water and likely in
the paint you have used in your house.