Effect of membrane removal on the production of calcium oxide from eggshells via calcination

Abstract

In the pursuit of a circular economy and against a background of viable alternative uses of avian eggshells and eggshell membranes, this research investigated the effect of domesticated chicken eggshell membrane separation on the calcination process and quality of Calcium Oxide (CaO) produced. Acetic acid was used to leach the eggshells for 60 min to aid separation of the shell membrane. X-ray diffraction, red green blue colour model, and thermogravimetric analyses were used to characterize the calcined shells. Leached and separated shells produced CaO of comparable quality and crystallinity to unseparated shells after calcination. Results showed that while leaching and membrane separation did not affect calcination temperature, residual ash from the membrane left impurities in the unseparated shells after calcination. It was concluded that leaching and separating the membranes from eggshells prior to calcination serves to upcycle eggshells by facilitating improved CaO production and membrane value extraction.