Bird eggshells have fascinated mankind for centuries because bird egg is one of the most nutritious foods consisting of protein, lipid, and carbohydrates. Bird eggs also contain vitamins and mineral elements that are necessary for the development of young and elderly people. Phase transformation of bird eggshells was investigated here quantitatively and qualitatively through an analysis by XRD. Most of raw bird eggshells show calcite (CaCO3) of the rhombohedral form at nearly 100 wt % and it changed to lime or calcium oxide (CaO) of the face-centered cubic form at 97.41 wt % mixed with a small amount of other oxide compounds such as MgO and Ca(OH)2 when the bird eggshells were calcined at 900 οC for 1 h. The calcium oxide had a N2 adsorption-desorption isotherm expressed as the type IV hysteresis loop and a small average pore diameter in the range of the meso-porosity. Furthermore, the samples were analyzed by FTIR, STA, XRF, TEM, BET, and a particle size analyzer. The calcined bird eggshell powder is potentially useful for a variety of applications and industries: ink; fertilizer; cosmetic; pharmaceutical; rubber; plastic, including acting as starting materials for gypsum and dielectric-magnetic materials.

Keywords: Bird eggshells, Phase transformation, Meso-porosity, Pyrolysis.