Exploring Growth Trends and Opportunities in the Global Sodium Hexametaphosphate Market

Sodium Hexametaphosphate: An Important Technical Compound

Structure and Properties
Sodium hexametaphosphate, also known as SHMP or sodium phosphate glass, has the chemical formula (NaPO3)6. It is a white, water-soluble powder that is odorless and has a slightly saline taste. The compound consists of a long-chain polymeric phosphate anion with repeating phosphate (PO43-) units linked together. This gives it a non-crystalline, amorphous glass-like structure with no distinct melting point.

In its pure form, SHMP is stable and non-toxic. However, it can decompose over time when exposed to moisture and produce orthophosphate and cyclic metaphosphate residues. This decomposition is accelerated at higher temperatures. SHMP has good water solubility, with one gram dispersing in around 1.5 ml of water at room temperature. It is also soluble in glycerol but insoluble in most organic solvents.

Applications in Water Treatment
One of the largest applications of SHMP is in water treatment, where it is used as a sequestrant and protective colloid. In this role, its long polymeric chain structure allows it to complex and deactivate metal ions like calcium, magnesium and iron that can cause scaling or discoloration in pipes, boilers, and other equipment.

By tying up these metal cations, SHMP inhibits their reaction with anions like carbonate, sulfate and phosphate to form scale deposits. It also prevents the metal hydroxides from precipitating out of solution by encasing them within its phosphate cage structure. This keeps facilities pipes and membranes clear while allowing the passage of water.

As a protective colloid, SHMP's large anionic chains physically coat and protect dispersed solid particles from recombining. This helps maintain unstable metal precipitates or clays in a persistently dispersed flocculated state. This has benefits for clarifying and softening water during treatment. The ability of SHMP to sequester multiple metal ions using a single molecule also makes