Thermal decomposition kinetics of synthesized calcite and fishery wastes such as shell of bivalves, and spines of a sea urchin

Abstract

The thermal decomposition mechanism of bivalves and sea urchin spines was investigated to evaluate the potential for using fishery waste material as thermal storage material. The thermal decomposition rate demonstrates an Arrhenius-type temperature relationship. Compared with a CaCO₃ reagent, shells and spines were efficiently thermally decomposed. Despite showing a significant difference in thermal decomposition rate, chemical composition, particle size, and specific surface area, the activation energy of thermal decomposition was only marginally different. The rate-limiting process in thermal decomposition processes could be caused by the CO₂ gas flux, which was emitted from the sample. The CO₂ flux is controlled not only by the geometric surface area, particle seize but also by the crystallographic morphology of the sample. The biologically originated calcite may have efficient heat exchangeability as thermal storage material due to its unique crystal figure and microstructure.