Calcium phosphate, monobasic

Monobasic calcium phosphate is primarily used in fertilizers. It also is used in baking powders as a mineral supplement in food as a buffer for pH control and as a stabilizer for plastics. 

Monobasic calcium phosphate may be prepared in the laboratory by the reaction of calcium carbonate with phosphoric acid ... 

Theodoratos, P., Papassiopi, N. Xenidis, A. 2002. Evaluation of monobasic calcium phosphate for the immobilization of heavy metals in contaminated soils from Lavrion. Journal of Hazardous Materials, 94, 135-146. 

Monobasic calcium phosphate [Ca(H2P04)2] is manufactured by crystallization after evaporation and cooling of a hot solution of lime [CaO or Ca(OH)2] and strong phosphoric acid (H3P04). The crystals are centrifuged, and the highly acidic mother liquor returned for reuse. This acid salt is also made by spray drying a slurry of the reaction product of lime and phosphoric acid. 

The solubility of calcium and phosphate in total parenteral nutrition (TPN) solutions is dependent on the pH of the solution. TPN solutions are, of course, clinically acceptable only when precipitation can be guaranteed not to occur. Dibasic calcium phosphate, for example, is soluble only to the extent of 0.3 g dm whereas monobasic calcium phosphate has a solubility of 18 g dm . At low pH the monobasic form predominates, while at higher pH values the dibasic form becomes available to bind with calcium and precipitates tend to form. ... 

Calcium dihydrogen tetraoxophosphate monobasic calcium phosphate monocalcium phosphate... 

Note The products obtained from commercial processes are not pure monobasic calcium phosphate. The superphosphate obtained from the HjS04 treatment is about 30% CaH4(P04)).H20, 10% CaHP04, 45% CaS04, 10% iron oxide, silica, alumina, etc. and 5% water it contains 18-21% available P2Os. The triple superphosphate obtained from the H2POt treatment contains from 43 to 50% available P205. 

Rock phosphate is used as fertilizer only for acid and humus-rich soils. Generally, phosphates are fertilized in the form of water- or acid-soluble compounds, derived from rock phosphate (processed mineral phosphate fertilizers). An example is superphosphate, a mixture of monobasic calcium phosphate and calcium sulfate (7-9% P). In double or triple superphosphate the P-con-tent rises to about 20%. Manures contain... 

Monobasic calcium phosphate, Ca(H2P04)2, is also known as calcium hypophosphite, calcium biphosphate, acid calcium phosphate, monocalcium orthophosphate, and primary calcium phosphate. It usually exists in the form of the hydrate Ca(H2P04)2-H20. It decomposes when heated to 2oo°C (400°F)... 

The dibasic and tribasic forms of calcium phosphate are insoluble in water and alcohol, but soluble in most acids. Monobasic calcium phosphate is soluble in water and acids, and insoluble in alcohol. All three compounds are non-flammable. 

Further applications are the examination of pigments, the detection of CaS04 used as a filler in paper (after ashing), the detection of adulteration of flour with gypsum, and the differentiation of superphosphate of lime (a mixture of monobasic calcium phosphate and calcium sulfate) from phosphate fertilizers containing no CaS04. 

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