Thermo-oxidative evolution and physico-chemical characterization of seashell waste for application in commercial sectors

•Successful thermally induced conversion of seashells into value-added products.•Isentropic oxidation which requires a large amount of heat causing entropy penalty.•According to XRD patterns CaCO3 is completely transformed into CaO at yet 850 °C.•Recommended high temperature to shifts reaction equilibrium towards decarbonation.•Agglomeration of CaO grains was favored by temperature-enhanced lattice diffusion.