Přímá syntéza nanokrystalického hydroxyapatitu hydrotermální syntézou alkylfosfátů

Direct synthesis of nanocrystalline hydroxyapatite by hydrothermal hydrolysis of alkylphosphates

journal article - other

en

The influence of reaction conditions (temperature, type of catalyst, time) on the base-catalyzed reaction of mono-, di-, and trialkylphosphates (alkyl=methyl, ethyl, i-propyl, n-butyl) with Ca2+ ions and on the structure and composition of the reaction products was studied. The composition of the calcium phosphates depends mainly on the reaction temperature. At temperatures below 100 degC, a nanocrystalline solid products transforming into dicalcium phosphate by heating (calcination) was found.Pure nanocrystalline hydroxyapatite was prepared by hydrothermal synthesis at 160 degC from mono- and dialkylphosphates. The size of hydroxyapatite crystallites was about 1 nm, the particle size about 150 um. Agglomerated particles of hydroxyapatite larger than 2 um were prepared at 200 degC. Hydrothermal reaction of trialkylphosphates with Ca2+ ions at 200 degC produced CaHPO4. The experimental results were used to propose a reaction mechanism for base-catalyzed hydrothermal reactions of alkylphosphates with Ca2+ ions.

Byl studován vliv reakčních podmínek (teplota, typ katalyzátoru, čas) na bazicky katalyzovanou reakci mono-, di-, and trialkyl fosfátů (alkyl=methyl, ethyl, i-propyl, n-butyl)s Ca2+ ionty a na strukturu a složení reakčních produktů. Složení kalcium fosfátů zaleželo především na reakční teplotě. Při teplotách pod 100 degC byly nalezeny nanokrystalické produkty, které při ohřevu (kalcinaci) trasformovaly na dikalcium fosfát. Čistý nanokrystalický hydroxyapatit byl připraven hydrotermální syntézou při 160 degC z mono- and dialkyl fosfátů. Velikost hydroxyapatitových krystalitů byla kolem 1 nm, velikost částic kolem 150 um. Hydrotermalní reakce trialkyl fosfátů s Ca2+ ionty při 200 degC produkovala CaHPO4. Experimentální výsledky byly použity k návrhu reakčního mechanismu bazicky katalyzované hydrotermální reakci alkyl fosfátů s Ca2+ ionty.

The influence of reaction conditions (temperature, type of catalyst, time) on the base-catalyzed reaction of mono-, di-, and trialkylphosphates (alkyl=methyl, ethyl, i-propyl, n-butyl) with Ca2+ ions and on the structure and composition of the reaction products was studied. The composition of the calcium phosphates depends mainly on the reaction temperature. At temperatures below 100 degC, a nanocrystalline solid products transforming into dicalcium phosphate by heating (calcination) was found.Pure nanocrystalline hydroxyapatite was prepared by hydrothermal synthesis at 160 degC from mono- and dialkylphosphates. The size of hydroxyapatite crystallites was about 1 nm, the particle size about 150 um. Agglomerated particles of hydroxyapatite larger than 2 um were prepared at 200 degC. Hydrothermal reaction of trialkylphosphates with Ca2+ ions at 200 degC produced CaHPO4. The experimental results were used to propose a reaction mechanism for base-catalyzed hydrothermal reactions of alkylphosphates with Ca2+ ions.

ceramics, synthesis, nanostructures, hydroxyapatite, hydrothermal synthesis, alkylphosphates

2002

01.01.2002

0026-9247

Monatshefte fuer Chemie

133

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