Adsorption of citrate ions on hydroxyapatite synthetized by various methods.

E Skwarek,W Janusz,D Sternik

doi:10.1007/s10967-013-2825-z

E Skwarek, W Janusz + Show 1 more

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https://doi.org/10.1007/s10967-013-2825-z

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Abstract

The specific adsorption of citric acid ions at hydroxyapatite interface was investigated by the means of radioisotope method (14C) as a function of citric acid ions concentration, NaCl concentration and pH. Application of the hydroxyapatite has become wide in the biomaterial field as the Ca10(OH)2(PO4)6 possess biocompatibility with human hard tissue. Hydroxyapatite was synthesized using three different methods. The physical properties of the resulting powder were characterized by DTA/TG, XRD, AFM and SEM microscopy. Physicochemical qualities characterizing the electrical double layer of the hydroxyapatite/NaCl solution interface were determined. The zeta potential and the adsorption of citric acid molecule were studied as a function of pH. The point of zero charge and the isoelectric point of samples were determined. Electrical double layer parameters of hydroxyapatite/NaCl interface are influenced by a synthesis method. The points pHpzc and pHIEP for sample 1 are pHpzc 7.5 and pHIEP 3; for sample 2 pHpzc 7.05 and pHIEP 3, for smaple 3 pHpzc 6.7 and pHIEP 3. Temperature has weak influence both on pure substance and with citric acid adsorbed, as derivatographic analysis has shown, and characterization of hydroxyapatite structure may be carried out by this thermal analysis. Two phenomena are responsible for citric acid adsorption: phosphate group’s replacement at hydroxyapatite surface by citric ions parallel to intraspherical complexes formation.

Highlights

Hydroxyapatite [Ca10(OH)2(PO4)6] has been studied for many years, due to its occurrence in natural environment and practical application
The specific adsorption of citric acid ions at hydroxyapatite interface was investigated by the means of radioisotope method (14C) as a function of citric acid ions concentration, NaCl concentration and pH
Electrical double layer parameters of hydroxyapatite/NaCl interface are influenced by a synthesis method

Summary

Introduction

Hydroxyapatite [Ca10(OH)2(PO4)6] has been studied for many years, due to its occurrence in natural environment and practical application. As a natural mineral it is present in igneous and metamorphic rocks. It is a major inorganic component of bones and teeth. Calcium phosphate and calcium carbonate are human hard tissues constituents, with the same structure as the natural mineral. Thanks to its crystallographic similarity with natural bone minerals, biocompatibility with hard tissues and with skin or muscle tissues, bioactivity, no toxicity, and implants made of synthetic hydroxyapatite (bioceramic hydroxyapatite) are used as an artificial bone substitute in orthopedic, neurosurgery, dental surgery, plastic surgery and dental applications [1,2,3,4]

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