From eggshells biowaste to hydroxyapatite biomaterial

Abstract

In the present study a biowaste, in the form of chicken eggshells, was used for producing a biomaterial – hydroxyapatite by a conventional chemical precipitation method. Hydroxyapatite is a major component of human hard tissues, such as bones and teeth, which makes it a paradigmatic bioactive material. The first step in the synthesis of hydroxyapatite from eggshells was the transformation of their main component calcium carbonate into calcium oxide at 1000 °C. Afterwards, calcium oxide was hydrated in order to produce calcium hydroxide. Hydroxyapatite was then synthesized by the addition of phosphoric acid. The phase composition of the eggshells was examined by the powder X-ray diffraction. The surface morphology of the sintered product was determined by the scanning electron microscope equipped with the energy dispersive spectrometer. Powder X-ray diffraction and scanning electron microscope analyses confirmed hydroxyapatite as the main phase of the final product. The reuse of chicken eggshells reduces the amount of biowaste, as well as the need for the biowaste management. This investigation shows that the eggshells can be a useful raw material for the synthesis of valuable biomaterials.