(560al) Reaction of Acetic Acid and Chicken Eggshells to Form Calcium Acetate

In this work, we analyze the effect of the particle size, acetic acid concentration and excess of acetic acid on the reaction of acetic acid and chicken eggshells to produce calcium acetate. Inductively coupled plasma mass spectroscopy (ICP-MS) and X-ray diffraction (XRD) were used to quantify the amount of calcium carbonate in chicken eggshells. Calcium acetate was qualitatively and quantitatively characterized by X-ray diffraction (XRD) and thermogravimetric analysis (TGA), respectively. The reaction was investigated using a face-centered central composite design (FCCD) and evaluating the optimal conditions to produce calcium acetate. A simplified shrinking-core model was fitted to the experimental data suggesting that the reaction is mass transfer limited. The highest experimental conversion achieved was 95.82% with an excess of moles of acid about 50%, an acid concentration of 5% w/w and a particle size of 175 μm. The predicted conversion obtained by the statistical model was 98.78 %, implying an error of 3%.