Calcium Perphosphate

Description

Calcium peroxyphosphate has the formula of CaHPO5 as the monooxyphosphate or Ca2P2O8 as the dioxyphosphate. For preparation of the monooxyphosphate, the acid is first prepared by adding P2O5 to 30% hydrogen peroxide and then adding the hydroxide or carbonate to the acid:
P2O5 + 2H2O2 +H2O ? 2H3PO5
Ca(OH)2 +H3PO5 ? CaHPO5 +H2O
The phosphorus pentoxide powder was suspended in carbon tetrachloride under stirring while cooled in an ice bath. Aqueous hydrogen peroxide was added drop wise to this suspension to form H3PO5. Calcium carbonate or calcium hydroxide slurry was added slowly to the formed inorganic concentrated peroxymonophosphoric acid layer in an ice bath. The precipitate was then filtered. The result is a dihydrate, CaHPO5·2H2O.