scholarly journals REACTION PRODUCTS OF ORTHOPHOSPHATES IN SOILS CONTAINING VARYING AMOUNTS OF CALCIUM AND MAGNESIUM

1967 ◽  
Vol 47 (3) ◽  
pp. 223-230 ◽  
Author(s):  
G. J. Racz ◽  
R. J. Soper
Keyword(s):  
Calcium Phosphate ◽  
Octacalcium Phosphate ◽  
Water Soluble ◽  
Dicalcium Phosphate ◽  
Dicalcium Phosphate Dihydrate ◽  
Reaction Products ◽  
Phosphate Dihydrate ◽  
Soluble Calcium ◽  
Calcium And Magnesium ◽  
Saturated Solutions

The reaction products formed when orthophosphates (pellets) were added to 22 soils, with different calcium and magnesium contents, were identified. Di-calcium phosphate dihydrate (CaHPO4∙2H2O) formed in the soils having a water-soluble calcium to magnesium ratio of approximately 1.5 or greater. Dicalcium phosphate dihydrate and/or dimagnesium phosphate trihydrate (MgHPO4∙3H2O) formed in soils having a water-soluble calcium to magnesium ratio of less than 1.5.Dicalcium phosphate dihydrate and dimagnesium phosphate trihydrate precipitated in filtrates of two dolomitic soils shaken for 15 min with saturated solutions of KH2PO4 and NH4H2PO4. Octacalcium phosphate (Ca4H (PO4)3∙3H2O) and trimagnesium phosphate tetrahydrate (Mg3 (PO4)2∙4H2O) precipitated in filtrates of these soils when saturated solutions of K2HPO4 and (NH4)2HPO4 were used.Trimagnesium phosphate twenty-two hydrate (Mg3 ((PO4)2∙22H2O) formed when dimagnesium phosphate trihydrate was added to a soil containing large amounts of magnesium.

Seeded Growth of Calcium Phosphates: Effect of Different Calcium Phosphate Seed Material

1976 ◽  
Vol 55 (4) ◽  
pp. 617-624 ◽  
Author(s):  
G.H. Nancollas ◽  
J.S. Wefel
Keyword(s):  
Calcium Phosphate ◽  
Tricalcium Phosphate ◽  
Calcium Phosphates ◽  
Octacalcium Phosphate ◽  
Dicalcium Phosphate ◽  
Dicalcium Phosphate Dihydrate ◽  
Seeded Growth ◽  
Seed Crystals ◽  
Phosphate Dihydrate ◽  
Supersaturated Solutions

The growth of calcium phosphates on seed materials, dicalcium PhosPhate dihydrate (DCPD), tricalcium phosphate (TCP), octacalcium phosphate (OCP), and hydroxyapatite (HAP) in stable supersaturated solutions has been studied under conditions of pH and concentration for which the predominant phases are 1, DCPD, and II, HAP. All seed crystals are good nucleators for DCPD in system I, but, aside from HAP itself, only OCP will readily induce growth under condition II.

Preparation of Calcium Phosphate Cement Utilizing Dicalcium Phosphate Dihydrate and Calcium Carbonate

2014 ◽  
Vol 608 ◽  
pp. 280-286
Author(s):  
Nudthakarn Kosachan ◽  
Angkhana Jaroenworaluck ◽  
Sirithan Jiemsirilers ◽  
Supatra Jinawath ◽  
Ron Stevens
Keyword(s):  
Calcium Carbonate ◽  
Calcium Phosphate ◽  
Calcium Phosphate Cement ◽  
Raw Materials ◽  
Setting Time ◽  
Dicalcium Phosphate ◽  
Dicalcium Phosphate Dihydrate ◽  
Cement Pastes ◽  
Setting Times ◽  
Phosphate Dihydrate

Calcium phosphate cement has been widely used as a bone substitute because of its chemical similarity to natural bone. In this study, calcium phosphate cement was prepared using dicalcium phosphate dihydrate (CaHPO4.2H2O) and calcium carbonate (CaCO3) as starting raw materials. The cement pastes were mixed and the chemistry adjusted with two different aqueous solutions of sodium hydroxide (NaOH) and disodium hydrogen phosphate (Na2HPO4). Concentrations of the solution were varied in the range 0.5 to 5.0 mol/L with the ratio of solid/liquid = 2 g/ml. The cement paste was then poured into a silicone mold having a diameter of 10 mm and a height 15 mm. Setting times for the cement were measured using a Vicat apparatus. XRD, FT-IR, and SEM techniques were used to characterize properties and microstructure of the cement. From the experimental results, it is clear that different concentrations of Na2HPO4 and NaOH have affected the setting times of the cement. The relationship between concentration of NaOH and Na2HPO4 and setting time, including final properties of the cement, is discussed.

scholarly journals SOME EFFECTS OF MOISTURE AND TEMPERATURE ON TRANSFORMATION OF MONOCALCIUM PHOSPHATE IN SOIL

1962 ◽  
Vol 42 (2) ◽  
pp. 229-239 ◽  
Author(s):  
W. C. Hinman ◽  
J. D. Beaton ◽  
D. W. L. Read
Keyword(s):  
Water Soluble ◽  
Dicalcium Phosphate ◽  
Dicalcium Phosphate Dihydrate ◽  
Inorganic P ◽  
Monocalcium Phosphate ◽  
Liesegang Rings ◽  
Phosphate Dihydrate ◽  
The Mean ◽  
Surrounding Soil

Pre-weighed monocalcium phosphate pellets, containing about 15 milligrams of P, were placed in 200 grams of soil and stored for 2 weeks at four moisture tensions and three temperatures. Pellet residues were then removed and the amount of phosphorus remaining was determined. Small cores containing pellet residues and the surrounding soil contacted by fertilizer solution were removed for determination of water-soluble and total inorganic P. Phosphate phases present at the granule sites and the surrounding soil were identified by their optical properties.The mean amount of phosphorus remaining at the granule sites was 20.2 per cent. Although both moisture tension and temperature significantly affected the quantity of phosphorus retained, no consistent trend was apparent. Residues remaining at the site of application were found to be mixtures of anhydrous and dihydrated dicalcium phosphate, with the latter predominating. Moisture tension and temperature did not greatly alter the proportion of the two phases.Periodic precipitates or Liesegang rings of dicalcium phosphate were formed in the soil surrounding monocalcium phosphate pellets. Dicalcium phosphate dihydrate was the predominant phase. The proportion of dihydrated to anhydrous dicalcium phosphate increased as the temperature decreased and as the moisture tension increased.Water-soluble P increased significantly with increased moisture tension and was significantly greater at 5 °C. than at either 16 or 27 °C. The mean of all treatments was 5.6 per cent. Increased amounts of dicalcium phosphate dihydrate in the surrounding soil seemed to be responsible for the increase in water solubility.Between 89.5 and 99.2 per cent of the added phosphorus was recovered in the water and acid extracts of soil cores containing about 1.4 cm.3 of soil.

scholarly journals Ensayo exploratorio de métodos e interacciones de elementos en la aplicación de fertilizantes en el cultivo de maíz

2016 ◽  
Vol 1 ◽  
pp. 07
Author(s):  
O. A. Caceros ◽  
P. González ◽  
I Hidalgo ◽  
B. Moscoso ◽  
W. R. Raun
Keyword(s):  
Ammonium Sulfate ◽  
Coastal Plain ◽  
Nitrogen Sources ◽  
Dicalcium Phosphate ◽  
P Availability ◽  
Dicalcium Phosphate Dihydrate ◽  
Reaction Products ◽  
Triple Superphosphate ◽  
Phosphate Dihydrate ◽  
N Source

Soil fertility studies have been conducted on the southern coastal plain of Guatemala for several years without showing significant response to phosphorus and sulfur fertilizer applications. In 1987, various exploratory trials were established to evaluate various methods of application for phosphorus, sulfur and nitrogen. Nitrogen sources evaluated were ammonium sulfate and urea. Beef manure was also evaluated in combination with ammonium sulfate. Various other N (as urea), P, S combinations were Included in this trial using CaSO4 as the S source. Banding phosphorus and nitrogen together especially ammonium sulfate with triple superphosphateprovided excellent response across locations. Due to the pH reduction within the NP band, H2PO4 availability at lower pH is Increased as has been demonstrated by others. Ammonium sulfate was by far a better N source compared to urea when applied alone and as such an S response was considered probable in 2 or the five locations. Gypsum applications were evaluated both as a source of sulfur and as an alternative to improving P availability by applying this source with triple superphosphate in a joint band. It was expected that the reaction products from applying gypsum and P together increase the P availability since the precipitated products (hypothesized, dicalcium phosphate dihydrate and dicalcium phosphate) would not be fixed and as such slowly available at low pH. Also If by combining triple superphosphate and gypsum in a joint hand, precipitation products DCIP and DCPD would reduce the amount of fertilizer P complexed with Fe and Al hydroxides and or allophane. Antagonistic Interactions were found between S and P which suggests that fertilizer P applications could induce S deficiencies (where S was not applied) since P may be replacing SO4 on the exchange complex of soils thought to have high anion exchange capacities and/or significant amounts of adsorbed SO4.

Structural changes during the hydrolysis of dicalcium phosphate dihydrate to octacalcium phosphate and hydroxyapatite

2015 ◽  
Vol 51 (4) ◽  
pp. 355-361 ◽  
Author(s):  
V. F. Shamrai ◽  
A. E. Karpikhin ◽  
A. Yu. Fedotov ◽  
V. P. Sirotinkin ◽  
S. M. Barinov ◽  
...  
Keyword(s):  
Structural Changes ◽  
Octacalcium Phosphate ◽  
Dicalcium Phosphate ◽  
Dicalcium Phosphate Dihydrate ◽  
Phosphate Dihydrate ◽  
Hydrolysis Of
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