Influence of some phosphates and polyphosphate on the precipitation of calcium sulfate dihydrate in sodium chloride solutions

The inhibiting effect of phosphates and polyphosphates on the precipitation rate of calcium sulfate dihydrate (gypsum) in sodium chloride solutions has been studied using constant composition technique in which the super-saturation and ionic strength were maintained constant at 25°C. The presence of phosphoric acid H3PO4, orthophosphate NaH2PO4, metaphosphate Na2HPO4,pyrophosphate PYP and hexametaphosphate HMP, even at relatively low...