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However, during the defluoridation process the hydroxyapatite dissolves, and increases the pH and phosphate ion concentration which makes the defluoridated water unfit for drinking. [46] Recently, a ″calcium amended-hydroxyapatite″ defluoridation technique was suggested to overcome the phosphate leaching from hydroxyapatite. [ 46 ]
Various calcium phosphate minerals, which often are not white owing to impurities, are used in the production of phosphoric acid and fertilizers. Overuse of certain forms of calcium phosphate can lead to nutrient -containing surface runoff and subsequent adverse effects upon receiving waters such as algal blooms and eutrophication (over ...
Negatives include higher costs and it skilled labour. This process is not suitable for water with high salinity. [2] Calcium amended-hydroxyapatite is the most recent defluoridation technique in which aqueous calcium is amended to the fluoride contaminated water prior to contact with uncalcined synthetic hydroxyapatite adsorbent. [8]
Amorphous calcium phosphate in combination with casein phosphopeptide has been used as a dental treatment to treat incipient dental decay. ACP sees its main use as an occluding agent, which aids in reducing sensitivity. Studies have shown that it does form a remineralized phase of hydroxyapatite consistent with the natural enamel.
Apatite is a group of phosphate minerals, usually hydroxyapatite, fluorapatite and chlorapatite, with high concentrations of OH −, F − and Cl − ion, respectively, in the crystal. The formula of the admixture of the three most common endmembers is written as Ca 10 ( PO 4 ) 6 (OH,F,Cl) 2 , and the crystal unit cell formulae of the ...
Tricalcium phosphate is produced commercially by treating hydroxyapatite with phosphoric acid and slaked lime. [4]It cannot be precipitated directly from aqueous solution. Typically double decomposition reactions are employed, involving a soluble phosphate and calcium salts, e.g. (NH 4) 2 HPO 4 + Ca(NO 3
Calcium hydroxyapatite and calcite precipitates can be found around bacteria in alluvial topsoil. [24] As clay minerals promote biomineralization, the presence of bacteria and clay minerals resulted in calcium hydroxyapatite and calcite precipitates. [24] Phosphate deposits can contain significant amounts of naturally occurring heavy metals.
Bone meal provides phosphorus and calcium to plants, along with a largely inconsequential amount of nitrogen. [4] The N-P-K rating of bone meal is typically 3–15–0 [5] along with a calcium content of around 12% (18% CaO equiv.), [6] although it can vary quite a bit depending on the source from 1–13–0 to 3–22–0.