Commercial sodium hexametaphosphate is a combination of different polyphosphates, which includes sodium polymetaphosphate. The hexamer is one of those polyphosphates.
To produce sodium hexametaphosphate using the sodium dihydrogen phosphate method, sodium dihydrogen phosphate dihydrate is heated to 110-230°C to remove two crystal waters and structural water. Then the mixture is heated further to 620°C for dehydration, which generates sodium metaphosphate melt that is polymerized into six sodium metaphosphate molecules. After unloading the mixture, it is cooled from 650°C to 60-80°C and turned into tablets. The tablets are then crushed to produce the finished product of sodium hexametaphosphate.
Sodium hexametaphosphate is a sequestering agent with broad applications in several industries, including as a food additive. To use it as a hard water softener and cleaning agent, sodium carbonate can be added to increase its pH value to 8.0-8.6.
