Paper Title:
Effects of pH on the Transformation of Gypsum to Carbonate Apatite in the Presence of Ammonium Hydrogen Phosphate
  Abstract

Effects of pH on the transformation of gypsum to apatite in the presence of ammonium hydrogen phosphate was studied using NH4H2PO4, (NH4)2HPO4 and (NH4)3PO4. When set gypsum was immersed to ammonium hydrogen phosphate, pH of the solution decreased regardless of the solution. Although pH of the solution decreased, no significant compositional change was observed when gypsum was immersed in NH4H2PO4. On the other hand, apatite and small amount of dicalcium phosphate anhydrous (CaHPO4) was formed when gypsum was immersed in (NH4)2HPO4 solution. Only apatite was formed when gypsum was immersed in (NH4)3PO4 solution. Although the detailed mechanism for the pH dependent products has not been clarified, one of the causes may be the different thermodynamical difference between gypsum and apatite. We would like to recommend the use of (NH4)3PO4 solution since this provides higher pH and thus larger thermodynamical difference between apatite and gypsum and resulting pure apatite block.

  Info
Periodical
Key Engineering Materials (Volumes 309-311)
Main Theme
Edited by
Takashi Nakamura, Kimihiro Yamashita and Masashi Neo
Pages
199-202
DOI
10.4028/www.scientific.net/KEM.309-311.199
Citation
I. Kunio, Y. Suzuki, S. Matsuya, M. Nakagawa, K. Koyano, "Effects of pH on the Transformation of Gypsum to Carbonate Apatite in the Presence of Ammonium Hydrogen Phosphate ", Key Engineering Materials, Vols. 309-311, pp. 199-202, 2006
Online since
May 2006
Export
Price
$32.00
Share

In order to see related information, you need to Login.

In order to see related information, you need to Login.

Authors: Hyun Min Kim, Hideki Kaneko, Tadashi Kokubo, Toshiki Miyazaki, Takashi Nakamura
11
Authors: S.B. Cho, Sang Bae Kim, Keon Joon Cho, Y.J. Kim, Tae Hee Lee, Y. Hwang
93
Authors: Ishikawa Kunio, Shigeki Matsuya, Yumiko Suzuki, Koh-ichi Udoh, Masaharu Nakagawa, Kiyoshi Koyano
Abstract:Present study evaluated the feasibility of apatite monolith preparation from calcium sulfate monolith using ammonium phosphate solution. We...
533
Authors: Akari Takeuchi, Akinari Nakagawa, Shigeki Matsuya, Ishikawa Kunio
Abstract:Effect of added α-tricalcium phosphate (α-TCP) and β-TCP was investigated to understand the setting reaction of apatite cement consisting of...
339
Authors: Kenkichi Sasaki, Ayako Oyane, Koji Hyodo, Atsuo Ito, Yu Sogo, Masanobu Kamitakahara, Koji Ioku
Abstract:A composite layer of fibroblast growth factor-2 (FGF-2) and low-crystalline apatite was formed on an ethylene-vinyl alcohol copolymer...
455