Consecutive Formations of Portlandite and Hydroxyapatite from Tricalcium  Phosphate in NaOH Concentrated Solutions near the Solubility Singular Point

Hideki MONMA; Toshinori OKURA; Satoshi TAKAHASHI

doi:10.14852/jcersjsuppl.112.0.S797.0

Journal of the Ceramic Society of Japan, Supplement 112-1, PacRim5 Special Issue

Session ID : 11

DOI https://doi.org/10.14852/jcersjsuppl.112.0.S797.0

Conference information

Host: The Ceramic Society of Japan

Co-host: Iketani Science and Technology Foundation, International Ceramic Federation, Commemorative Organization for the Japan World Exposition '70, The American Ceramic Society, The Australasian Ceramic Society, The Chinese Ceramic Society, The Korean Ceramic Society, Joint Research Consortium of Synergy Ceramics/Fine Ceramics Research Association, Nanotechnology Researchers Network Center of Japan, The Special Coordination Funds for Promoting Science and Technology, Japan National Tourist Organization, Aichi Prefectural Government, CASIO SCIENCE PROMOTION FOUNDATION, DAIKO FOUNDATION, Nagoya Convention and Visitors Bureau, The Asahi Glass Foundation, The Kao Foundation For Arts And Sciences, The Murata Science Foundation, The Ogasawara Foundation for the Promotion of Science & Engineering, ASAHI GLASS CO., LTD. Research Center, CENTRAL GLASS CO., LTD., ELECTRIC GLASS INDUSTRY ASSOCIATION OF JAPAN (EGAJ), Hattori Company, Ltd., Hitachi Research Laboratory, Hitachi, Ltd., HOYA CORPORATION, INAX Corporation, ITOCHU CERATECH CORP., Japan Cement Association, KYOCERA Corporation, KYUSHU REFRACTORIES CO., LTD., MINO CERAMIC CO., LTD., Murata Manufacturing Co., Ltd., NGK INSULATORS LTD., NGK SPARK PLUG CO., LTD., NICHIAS Corporation, NIKKO COMPANY, Nippon Electric Glass Co., Ltd., Nippon Sheet Glass Co., Ltd., NORITAKE CO., LIMITED, Tokuyama Corporation, TOTO LTD.

Papers

Consecutive Formations of Portlandite and Hydroxyapatite from Tricalcium Phosphate in NaOH Concentrated Solutions near the Solubility Singular Point

Hideki MONMA, Toshinori OKURA, Satoshi TAKAHASHI

Author information

Keywords: Hydroxyapatite, Portlandite, Singular point

CONFERENCE PROCEEDINGS FREE ACCESS

Details

Abstract

The reaction of tricalcium phosphate (TCP) with 25-40 mass% NaOH solutions was investigated at 90°C. At 25-33 mass% TCP was converted consecutively into portlandite (Ca(OH)₂) and hydroxyapatite (HAp). The first step of the consecutive reaction TCP→Ca(OH)₂→HAp was fast and completed. The second step proceeded gradually and completely at 25 mass%, whereas at 30-33 mass% seemed to reach an equilibrium mixture of ca. 85% HAp and 15% Ca(OH)₂. At 34-40 mass% a simple reaction of TCP→Ca(OH)₂ occurred fast and completely. The solubility singular point in the system HAp-Ca(OH)₂-NaOH-H₂O was 32 mass% (10.7 mol/dm³) NaOH. These chemical properties of TCP in NaOH concentrated solutions are of very interest as TCP has been thought to be stable in high pH solutions.

Corresponding author

Register with J-STAGE for free!