Isotherm, adsorption hydroxyapatite

Adsorption and Electrokinetic Behavior of Hydroxyapatite. The adsorption densities of glutamic acid and lysine on hydroxyapatite are shown in Flgures b and 7. The change in slope of the adsorption isotherm at 10 M glutamic acid is considered to be due to a... 

Leyva et al. (2001) studied Sb(III) adsorption to hydroxyapatite. They conducted adsorption isotherms in closed vessels at Sb concentrations of 0.05-50 mg/L, constant I (0.01 m), constant solid phase concentrations of 10g/dm3 at pH values between 5 and 8. The hydroxyapatite was characterized by X-ray diffraction (XRD), SF.M-F.DS, X-ray photoelectron spectroscopy (XPS), and infrared (IR) spectroscopy. Langmuir adsorptions models revealed Fmax of 6.7 x 10 xmol/m2 and Xads = 1.5 x 103dm3/mol. As Sb adsorption occurred, the isoelectric point (pHicp) of the hydroxyapatite changed from 4.0 to 12.0. The decline in the pHjep during sorption as well as the absence of... 

The mechanism of interaction of amino acids at solid/ aqueous solution interfaces has been investigated through adsorption and electrokinetic measurements. Isotherms for the adsorption of glutamic acid, proline and lysine from aqueous solutions at the surface of rutile are quite different from those on hydroxyapatite. To delineate the role of the electrical double layer in adsorption behavior, electrophoretic mobilities were measured as a function of pH and amino acid concentrations. Mechanisms for interaction of these surfactants with rutile and hydroxyapatite are proposed, taking into consideration the structure of the amino acid ions, solution chemistry and the electrical aspects of adsorption. 

Figure 6. The isotherm for adsorption of glutamic acid on hydroxyapatite.

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