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Adsorption of citrate ions on hydroxyapatite synthetized by various methods.

Skwarek E, Janusz W, Sternik D - J Radioanal Nucl Chem (2013)

Bottom Line: The physical properties of the resulting powder were characterized by DTA/TG, XRD, AFM and SEM microscopy.The point of zero charge and the isoelectric point of samples were determined.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.

View Article: PubMed Central - PubMed

Affiliation: Faculty of Chemistry, Maria Curie-Sklodowska University, Maria Curie-Sklodowska Sq. 5, 20-031 Lublin, Poland.

ABSTRACT

The specific adsorption of citric acid ions at hydroxyapatite interface was investigated by the means of radioisotope method ((14)C) 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.

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The surface charge density HAP/NaCl solution interface as a function of pH samples 1, 2, 3
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Fig4: The surface charge density HAP/NaCl solution interface as a function of pH samples 1, 2, 3

Mentions: The surface charge density as a function of pH for studied samples in 0.001 M NaCl aqueous solution are depicted in Fig. 4 As it can be seen in the studied pH range the values surface charge density are negative, so pHpzc can be determined by extrapolation method. The obtained values for the samples are as follows 7.5 for sample 1, 7.05 for sample 2 and 6.7 for sample 3. Additionally course of the dependence of surface charge density vs. pH shows that acidic properties of surface groups arranges in the following sequence sample 3 > sample 2 sample1. These properties are results of the decreasing amount of calcium ions in the sample determined using EDAX method that is following 29.2 atom % for sample 1, 23.8 at.% for sample 2 and 22.9 at.% for sample 3. The increase of amount of calcium atoms in the sample lead to increase base properties of surface groups that is seen as a shift o pHpzc towards higher pH.Fig. 4


Adsorption of citrate ions on hydroxyapatite synthetized by various methods.

Skwarek E, Janusz W, Sternik D - J Radioanal Nucl Chem (2013)

The surface charge density HAP/NaCl solution interface as a function of pH samples 1, 2, 3
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4514589&req=5

Fig4: The surface charge density HAP/NaCl solution interface as a function of pH samples 1, 2, 3
Mentions: The surface charge density as a function of pH for studied samples in 0.001 M NaCl aqueous solution are depicted in Fig. 4 As it can be seen in the studied pH range the values surface charge density are negative, so pHpzc can be determined by extrapolation method. The obtained values for the samples are as follows 7.5 for sample 1, 7.05 for sample 2 and 6.7 for sample 3. Additionally course of the dependence of surface charge density vs. pH shows that acidic properties of surface groups arranges in the following sequence sample 3 > sample 2 sample1. These properties are results of the decreasing amount of calcium ions in the sample determined using EDAX method that is following 29.2 atom % for sample 1, 23.8 at.% for sample 2 and 22.9 at.% for sample 3. The increase of amount of calcium atoms in the sample lead to increase base properties of surface groups that is seen as a shift o pHpzc towards higher pH.Fig. 4

Bottom Line: The physical properties of the resulting powder were characterized by DTA/TG, XRD, AFM and SEM microscopy.The point of zero charge and the isoelectric point of samples were determined.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.

View Article: PubMed Central - PubMed

Affiliation: Faculty of Chemistry, Maria Curie-Sklodowska University, Maria Curie-Sklodowska Sq. 5, 20-031 Lublin, Poland.

ABSTRACT

The specific adsorption of citric acid ions at hydroxyapatite interface was investigated by the means of radioisotope method ((14)C) 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.

No MeSH data available.


Related in: MedlinePlus