Conversion of Marine Structures to Calcium Phosphate Materials: Mechanisms of Conversion Using Two Different Phosphate Solutions

Abstract : Marine structure, coralline materials were converted to calcium phosphate using two different phosphate solutions. The aim was to study the conversion mechanisms under acidic and basic environment at moderate conditions of temperature. Crystal growth and morphology of converted corals were characterized by XRD and SEM respectively. The results suggested that under acidic conditions (H3PO4), dissolution and precipitation control and direct the crystal formation and morphology in which transition from plate like to rod like hydroxyapatite structure was favoured. Metastable phase such as monetite formed and transformed to HAp during reaction. During the first hour of the dissolution a monetite and hydroxyapatite mixture precipitates and then the full conversion to hydroxyapatite is observed. On the other hand, under basic conditions (NH4)2HPO4, just diffusional surface conversion of the calcium carbonate structure of coralline materials to hydroxyapatite and a very small amount of tri-calcium phosphate is observed. The mechanism can be classified as the solid-state topotactic ion-exchange reaction mechanism.
Document type :
Journal articles
Complete list of metadatas

Cited literature [6 references]  Display  Hide  Download

https://hal.archives-ouvertes.fr/hal-01445043
Contributor : Open Archive Toulouse Archive Ouverte (oatao) <>
Submitted on : Tuesday, January 24, 2017 - 3:13:10 PM
Last modification on : Friday, June 14, 2019 - 6:31:14 PM
Long-term archiving on : Tuesday, April 25, 2017 - 6:14:07 PM

File

macha_16545.pdf
Files produced by the author(s)

Identifiers

Collections

Citation

Innocent J. Macha, David Grossin, Besim Ben-Nissan. Conversion of Marine Structures to Calcium Phosphate Materials: Mechanisms of Conversion Using Two Different Phosphate Solutions. Key Engineering Materials, Trans Tech Publications, 2016, vol. 696, pp. 36-39. ⟨10.4028/www.scientific.net/KEM.696.36⟩. ⟨hal-01445043⟩

Share

Metrics

Record views

106

Files downloads

152