Study of Addition Speed of Reagents in the Synthesis of Hydroxyapatite by the Sol-gel Method Using Chicken Eggshells as Precursors

Reference	Presenter	Authors (Institution)	Abstract
02-004	ADILSON QUIZUNDA	AGUILAR, M.S.(UNIVERSIDADE ESTÁCIO DE SÁ); DE CAMPOS, J.B.(UNIVERSIDADE ESTADUAL DO RIO DE JANEIRO); Di LELLO, B.C.(UNIVERSIDADE ESTÁCIO DE SÁ); QUIZUNDA, A.([email protected]); Moura, F.J.(PONTIFÍCIA UNIVERSIDADE CATÓLICA); RAMOS, V.S.(Universidade Estadual do Rio de Janeiro);	Hydroxyapatite (HAP) has been the subject of much research in several areas, mainly in its use as a bone implant. The method of obtaining by sol-gel was chosen to be used in this work. During the execution of the reaction, the drip time of the reagents influences the morphological and crystallographic characteristics of the hydroxyapatite obtained. In this work, the hydroxyapatite powders were synthesized by the sol-gel method, with the use of chicken eggs as precursors of calcium carbonate. First the eggshells were washed and calcined at 1000 ° C to obtain calcium oxide (CaO) which was reacted with water for conversion to Ca(OH)2. The addition of phosphoric acid to Ca(OH)2 was then carried out under both heating and pH control between 9 and 11 by addition of NH4OH. At this point several rates of reagent addition were studied, such as direct addition and addition by dripping. The gel was filtered and washed with deionized water for the purpose of the removal of any reaction co-product. The green hydroxyapatite was oven dried for 12h at 300 ° C. The last stage of the synthesis consisted in calcination of the material obtained after drying at a temperature of 1000 ° C. The samples were characterized by X-ray diffraction, which was performed to obtain the crystallographic characterization of solids and by X-ray Dispersive Energy Spectrometry, to identify the chemical elements present. The analysis of the XRD spectra of the powders obtained showed that the addition rate of the regents had an influence on the composition and the degree of phase transformation of the powders obtained. Depending on the addition of the reagents, it was obtained hydroxyapatite as pure phase or as amorphous phase with a mixture of several calcium oxides. In the 100% HAP sample, EDS measurements indicated the presence of Ca, O and P, without any contamination.
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