The point of zero charge of hydroxyapatite and fluorapatite in aqueous solutions

Bell, L. C.; Posner, A. M.; Quirk, J. P.

doi:10.1016/0021-9797(73)90288-9

Cited by 184 publications

(74 citation statements)

References 19 publications

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“…The pH pzc of the HA-uc and HA-c samples was found to be 7.5 and 7.9, respectively, in good agreement with literature data (Bell et al 1973). Hence, the surface of the HAp samples becomes positive charged for pH < pH pzc and negative for pH > pH pzc .…”

Section: Characterization Of Absorbentssupporting

confidence: 77%

Kinetic and equilibrium studies on adsorption of Reactive Blue 19 dye from aqueous solutions by nanohydroxyapatite adsorbent

Ciobanu

Barna

Harja

2016

Archives of Environmental Protection

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Abstract:In the present study the adsorption of Reactive Blue 19 dye on the hydroxyapatite (HAp) nanopowders was investigated. The batch adsorption experiments were performed by monitoring the adsorbent dosage, contact time, dye solution concentration, pH and temperature. At pH 3 and 20ºC, high dye removal rates of about 95.58% and 86.95% for the uncalcined and calcined nanohydroxyapatites, respectively, were obtained. The kinetic studies indicated the dye adsorption onto nanohydroxyapatite samples to follow a pseudo-second order model. The Langmuir isotherm was found to be the best to represent the equilibrium with experimental data. The maximum adsorption capacity of uncalcined and calcined nanohydroxyapatite samples has been found to be 90.09 mg/g and 74.97 mg/g, respectively.

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Section: Characterization Of Absorbentssupporting

confidence: 77%

Kinetic and equilibrium studies on adsorption of Reactive Blue 19 dye from aqueous solutions by nanohydroxyapatite adsorbent

Ciobanu

Barna

Harja

2016

Archives of Environmental Protection

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“…ions from the solution and Ca 2? ions from the solid phase take place (Bell et al 1973). The specific sorption of Na ?…”

Section: Resultsmentioning

confidence: 99%

Study of sorption processes of strontium on the synthetic hydroxyapatite

Janusz

Skwarek

2016

Adsorption

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Adsorption of 90 Sr on hydroxyapatite is important in many fields of life. The aim of the paper was to discuss the changes in the double electrical layer at the hydroxyapatite/electrolyte solution interface during Sr ions adsorption and to establish the relations between time and adsorption on this material. Hydroxyapatite was prepared by the wet method, characterized by the X-ray diffraction and accelerated surface area and porosimetry methods. Studies of adsorption were carried out using 90 Sr isotopes and ionic solutions containing this ion depending on concentration and pH of the solution. Sr adsorption isotherms on hydroxyapatite were determined and the effect of strontium ions presence on the surface charge density and zeta potential was discussed.

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“…For this reason, the authors have placed the measurement outputs made in 25°C. Smičiklas et al [12], Bell et al [13] and Janusz et al [14] give the values of pH PZC Dependence of surface charge density on pH allows to calculate the values of ionization and complexation equilibrium constants of surface hydroxyl groups. The constants were calculated as the fitting parameters for calculated model of ion adsorption reactions at the salt/electrolyte solution interface.…”

Section: Resultsmentioning

confidence: 99%

Thermal analysis of hydroxyapatite with adsorbed oxalic acid

Skwarek

2015

J Therm Anal Calorim

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The specific adsorption of oxalic acid ions at the hydroxyapatite interface was investigated by means of the radioisotope method ( 14 C) as a function of oxalic acid ions concentration, NaCl concentration and pH. Application of hydroxyapatite has become extensive in the biomaterial field due to its biocompatibility with human hard tissue. Hydroxyapatite was synthesized using wet methods. Physical properties of the resulting powder were characterized by DTA/TG, XRD, AFM and SEM microscopy. Physicochemical properties characterizing the electrical double layer of the hydroxyapatite/NaCl solution interface were determined. The zeta potential and the adsorption of oxalic acid molecules were studied as a function of pH. The point of zero charge and the isoelectric point of samples were determined: its values are as follows: pH PZC = 7 and pH IEP = 4. Temperature has insignificant influence on pure substance and with oxalic acid adsorbed, as thermal analysis has shown, and characterization of hydroxyapatite structure can be carried out by this thermal analysis. Two phenomena are responsible for oxalic acid adsorption: phosphate group replacement at the hydroxyapatite surface by oxalic ions simultaneous to intraspherical complexes formation.

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The point of zero charge of hydroxyapatite and fluorapatite in aqueous solutions

Cited by 184 publications

References 19 publications

Kinetic and equilibrium studies on adsorption of Reactive Blue 19 dye from aqueous solutions by nanohydroxyapatite adsorbent

Kinetic and equilibrium studies on adsorption of Reactive Blue 19 dye from aqueous solutions by nanohydroxyapatite adsorbent

Study of sorption processes of strontium on the synthetic hydroxyapatite

Thermal analysis of hydroxyapatite with adsorbed oxalic acid

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