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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 ]
The following chart shows the solubility of various ionic compounds in water at 1 atm pressure and room temperature (approx. 25 °C, 298.15 K). "Soluble" means the ionic compound doesn't precipitate, while "slightly soluble" and "insoluble" mean that a solid will precipitate; "slightly soluble" compounds like calcium sulfate may require heat to precipitate.
As such, soil type plays a role, because it will affect the water content of the environment. For example, some soils, like clay soils, retain water better than others, like sandy or silty soils. Further, acidic soils are better able to dissolve the inorganic matrix of hydroxyapatite than basic soils, thus accelerating the disintegration of ...
The tables below provides information on the variation of solubility of different substances (mostly inorganic compounds) in water with temperature, at one atmosphere pressure. Units of solubility are given in grams of substance per 100 millilitres of water (g/(100 mL)), unless shown otherwise. The substances are listed in alphabetical order.
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.
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
A solubility equilibrium exists when a chemical compound in the solid state is in chemical equilibrium with a solution containing the compound. This type of equilibrium is an example of dynamic equilibrium in that some individual molecules migrate between the solid and solution phases such that the rates of dissolution and precipitation are equal to one another.