Özet:

ABSTRACT The crystallization of hydroxyapatite (HAP) was analyzed in a batch system in pure medium and in the presence of butyric acid as an additive. The experiments were conducted at different additive concentrations and the influences of the additive were investigated. Firstly, the crystals obtained were characterized by X-ray diffraction, Brunauer–Emmett–Teller, transmission electron microscopy, zeta potential measurement, Fourier transform infrared spectroscopy, and thermogravimetric analysis. The structure, surface areas, morphology, surface potential charges, functional groups and thermal decomposition behavior of the crystals were determined. In the next step, thermal decomposition kinetic profiles were modeled using the distributed activation energy model (DAEM), Flynn-Wall-Ozawa (FWO) and Friedman models. All the models used provided accurate fits of the TGA data with acceptably high R2 values. The value for the crystals obtained from the butyric acid containing medium was about 589 kJ/mol higher than that found for the crystals from the pure medium (538 kJ/mol). According to the results of the characterization and kinetic analysis, butyric acid could be employed as an additive for the production of HAP crystals with the desired quality and physical properties.

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