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By-product Gypsum
Published in Manjit Singh, Gypsum & Gypsum Products, 2023
On calcining phosphogypsum at 750°C to anlydrite, the impurities of dicalcium phosphate (CaHPO4.2H2O) gets converted into calcium pyrophosphate (Ca2P2O3). It is insoluble in water and thus harmless. Data obtained before and after calcination showed no loss of P2O5 on heating but reduction in fluoride content through volatilization.
Phase-Change Materials
Published in George A. Lane, Solar Heat Storage: Latent Heat Materials, 1986
Dibasic sodium phosphate, Na2HPO4, is also known as DSP, disodium phosphate, disodium orthophosphate, sodium orthophosphate, or disodium hydrogen phosphate. It is a common chemical, widely used in industry. It is produced either by reacting soda ash with phosphoric acid, or by treating dicalcium phosphate with soda ash. All these raw materials are cheap and readily available.
Phosphorus
Published in Brian D. Fath, Sven E. Jørgensen, Megan Cole, Managing Global Resources and Universal Processes, 2020
John Ryan, Hayriye Ibrikci, Rolf Sommer, Abdul Rashid
In acid soils, hydrous oxides of Fe and Al readily react with added soluble P, resulting in precipitation, while in neutral or calcareous soils, Ca controls P reactions. In Ca dominated systems, precipitates in the following order of solubility have been identified: monocalcium phosphate, dicalcium phosphate dihydrate, and hydroxyapatite or fluorapatite; the latter compound has extremely low solubility and thus controls solution P concentration. In acid soils, few well-crystallized P compounds have been observed. Reactions of soluble P with solid-phase components also involve sorption onto adsorbing surfaces. In effect, it is difficult to separate the process of precipitation from sorption. However, there is evidence that regardless of the mechanism involved, these reactions can be reversed. Precipitation/dissolution processes differ from sorption/desorption in that the solubility product of the least soluble P compound governs solution P concentration, whereas solution P controls the amount of P sorbed. In essence, retention of soluble P by soil components is a continuum between precipitation and surface reactions. In practice, P sorption curves or isotherms have been used extensively to describe the relationship between the amount of P sorbed or removed from solution by soils and that remaining in solution. Such isotherms have been used to identify sorption maxima, bonding energy between soils, and the equilibrium P concentration at which no sorption or desorption occurs.
Preparation, characterization and bioactivities of nano anhydrous calcium phosphate added gelatin–chitosan scaffolds for bone tissue engineering
Published in Journal of Biomaterials Science, Polymer Edition, 2019
Yogendra Pratap Singh, Sudip Dasgupta, Rakesh Bhaskar
Dicalcium phosphate anhydrous (DCPA) was prepared using CaCO3 as source of calcium and H3PO4 as source of phosphorus in ethanol solvent. DCPA with a Ca/P molar ratio of 0.5 was synthesized using sol–gel method. Two molar phosphoric acid (H3PO4) was added dropwise to 1 M ethanol solution of CaCO3, with continuous stirring in a sealed container. The mixture was stirred for a further 6 h at room temperature, resulting in white precipitates settling at the bottom of the beaker. The precipitate was separated from the solution using centrifugation and washed repeatedly using ethanol to remove the impurities. The obtained DCPA powder was dried at 80 °C for 20 h in a vacuum oven (Figure 2).