Solubility of salts in water: Key issue for crystal growth and dissolution processes

2007 ◽  
Vol 79 (5) ◽  
pp. 825-850 ◽  
Author(s):  
Petros G. Koutsoukos ◽  
Aikaterini N. Kofina ◽  
Dimitra G. Kanellopoulou
Keyword(s):  
Crystal Growth ◽  
Surface Diffusion ◽  
Calcium Phosphates ◽  
Ammonium Phosphate ◽  
Bulk Diffusion ◽  
Water Soluble ◽  
Alkaline Solutions ◽  
Magnesium Ammonium Phosphate ◽  
Magnesium Ammonium ◽  
Kinetics Of

The formation of sparingly soluble salts from aqueous solutions and their dissolution has attracted broad research interest. Of particular importance is the formation and transformation of minerals exhibiting polymorphism or encountered in more than one crystalline phase as, for example, in the case of calcium phosphates, formed in biological mineralization and in industrial-scale deposits. Understanding of these processes depends primarily on the equilibrium between the mineral phases considered and the aqueous medium in contact. Precipitation takes place in supersaturated solutions with rates depending on the solution supersaturation. The experimental investigation may reveal mechanistic details if done at sustained supersaturation. The kinetics of crystal growth depends either on surface diffusion or on bulk diffusion, which in turn is controlled by the medium fluid dynamics. In the case of magnesium ammonium phosphate (struvite), the presence of water-soluble organic compounds is responsible for the retardation both of the time needed for the onset of precipitation and for the kinetics of growth of the supercritical nuclei. Dissolution processes are controlled by the same mechanisms. In the case of calcitic marble, the dissolution in alkaline solutions is controlled by surface diffusion. Compounds active at the marble/water interface may in this case be used as protective agents.

Calcium Phosphates as Fillers in Struvite Cements

2005 ◽  
Vol 284-286 ◽  
pp. 161-164 ◽  
Author(s):  
F.C.M. Driessens ◽  
M.G. Boltong ◽  
R. Wenz ◽  
J. Meyer
Keyword(s):  
Calcium Phosphate ◽  
Calcium Phosphates ◽  
Ammonium Phosphate ◽  
Magnesium Ammonium Phosphate ◽  
Setting Times ◽  
Magnesium Ammonium ◽  
Series Of Experiments ◽  
Concentrated Solution ◽  
Magnesium Compound ◽  
Phosphate Filler

Struvite or magnesium ammonium phosphate MgNH4PO4 has been proposed as active component in setting surgical cements. The usual formulation is one in which the magnesium component in the powder is either magnesium hydrogen phosphate trihydrate or trimagnesium phosphate or a mixture of these two compounds. As the cement liquid a concentrated solution of diammonium phosphate is taken. To make the cement attractive as a bone substitute material a calcium phosphate filler is generally incorporated. Thus such materials are a type of pseudo calcium phosphate cements. This study was intended to find out which calcium phosphate and which magnesium compound are the most suitable. In the first series of experiments a mixture of 12 g Mg3(PO4)2 and 4 g MgHPO4.3H2O was used as the magnesium component in the powder. To that powder 30 g of either precipitated hydroxyapatite PHA or CaHPO4 or CaHPO4.H2O or b-TCP or a-TCP was added. The cement liquid was a 3.5 M solution of (NH4)2HPO4. At specific liquid/powder ratios L/P suitable setting times were obtained for the different formulations. However, the compressive strengths after immersion of the cements in 0.9% saline solution at 37°C varied over a large range. The best formulation was that with a-TCP which reached a compressive strength of 57 MPa after 18 h of immersion. In the second series of experiments 20 g of Mg3(PO4)2 was used as the magnesium component in the powder. Again 30 g of either of the above mentioned calcium phosphates was used as filler and again a 3.5 M solution of (NH4)2HPO4 was used as the cement liquid. At the appropriate L/P ratios the respective setting times were longer than in the first series of experiments but all five formulations appeared to result in good compressive strengths varying from 41 MPa for the formulation with b-TCP to 67 MPa for the formulation with PHA. In the third series of experiments 30 g a-TCP was taken as the calcium phosphate in the powder. As magnesium components mixtures of Mg3(PO4)2.8H2O and MgHPO4.3H2O and Mg3(PO4)2 were used. Again the cement liquid consisted of a 3.5 M solution of (NH4)2HPO4. The formulations with Mg3(PO4)2.8H2O had the shortest setting times and the lowest compressive strengths, whereas those with Mg3(PO4)2 had the longest setting times and the highest compressive strengths. Therefore, it is advantageous to use Mg3(PO4)2 as the magnesium component.

scholarly journals A Giant Ureteral Stone without Underlying Anatomic or Metabolic Abnormalities: A Case Report

2013 ◽  
Vol 2013 ◽  
pp. 1-3 ◽  
Author(s):  
Selcuk Sarikaya ◽  
Berkan Resorlu ◽  
Ekrem Ozyuvali ◽  
Omer Faruk Bozkurt ◽  
Ural Oguz ◽  
...  
Keyword(s):  
Ureteral Stone ◽  
Ammonium Phosphate ◽  
Intravenous Urography ◽  
Metabolic Abnormalities ◽  
Magnesium Ammonium Phosphate ◽  
Distal Ureter ◽  
Double J Stent ◽  
Magnesium Ammonium ◽  
Left Flank Pain ◽  
Plain Abdominal Film

A 28-year old man presented with left flank pain and dysuria. Plain abdominal film and computed tomography showed a left giant ureteral stone measuring 11.5 cm causing ureteral obstruction and other stones 2.5 cm in size in the lower pole of ipsilateral kidney and 7 mm in size in distal part of right ureter. A left ureterolithotomy was performed and then a double J stent was inserted into the ureter. The patient was discharged from the hospital 4 days postoperatively with no complications. Stone analysis was consistent with magnesium ammonium phosphate and calcium oxalate. Underlying anatomic or metabolic abnormalities were not detected. One month after surgery, right ureteral stone passed spontaneously, left renal stone moved to distal ureter, and it was removed by ureterolithotomy. Control intravenous urography and cystography demonstrated unobstructed bilateral ureter and the absence of vesicoureteral reflux.

In vitro production of struvite by Bacillus pumilus

1991 ◽  
Vol 37 (12) ◽  
pp. 978-983 ◽  
Author(s):  
Berlin Nelson ◽  
James Struble ◽  
Gregory McCarthy
Keyword(s):  
Bacillus Pumilus ◽  
Potassium Phosphate ◽  
Ammonium Phosphate ◽  
Maximum Size ◽  
In Vitro Production ◽  
Magnesium Ammonium Phosphate ◽  
X Ray ◽  
Magnesium Ammonium ◽  
Vitro Production

A strain of Bacillus pumilus, isolated from the soilborne sclerotia of a fungus, produced crystals of the mineral struvite (magnesium ammonium phosphate hexahydrate) on Difco nutrient agar and a yeast extract agar containing magnesium sulphate and potassium phosphate. Crystals were macroscopically observed after 6–20 days of bacterial growth and reached a maximum size of 3 × 0.5 mm. Crystals were identified by X-ray powder diffractometry. These findings support the hypothesis that bacteria are involved in the biogenic formation of struvite in nature. Key words: struvite, magnesium ammonium phosphate hexahydrate, Bacillus pumilus, biomineral.

Annual changes of the incidence and clinical characteristics of magnesium ammonium phosphate urinary stones

2003 ◽  
Vol 10 (1) ◽  
pp. 1-5 ◽  
Author(s):  
TAKAHIDE OGATA ◽  
KOICHIRO AKAKURA ◽  
KEN-ICHI MIZOGUCHI ◽  
KAZUO MIKAMI ◽  
KUNIYOSHI NOZUMI ◽  
...  
Keyword(s):  
Clinical Characteristics ◽  
Ammonium Phosphate ◽  
Urinary Stones ◽  
Magnesium Ammonium Phosphate ◽  
Magnesium Ammonium ◽  
Annual Changes
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