Prepared conch shell fragments were heated through calcination in a muffle furnace (Vulcan A-130 Furnace, USA). For comparison, this study utilized two different temperatures: (1) the standard temperature of 800˚C as recommended by Nordin et al. (2015) and (2) a higher temperature of 900˚C based on the study of Aydin and Kalemtas (2021) . Both sample sets were subjected to heat for 2 hours in gradual increase to obtain proper calcination of seashells. It has been proven that when the shell is heated at 700°C or above, shell microparticles convert its calcium carbonate (CaCO 3 ) into calcium oxide (CaO) (Alvarado and Quintana, 2022; Dampang et al., 2021; Nordin et al., 2015; Tongwanichniyom et al., 2021) . This calcination process is presented in the following equation:
After calcination, shell fragments were further pulverized using mortar and pestle. The resultant solid product was sifted using a sterilized stainless steel sieve to obtain 150μm-sized microparticles. Lastly, the powder was stored in air-tight wrapped crucibles inside a desiccator.
After calcination, shell fragments were further pulverized using mortar and pestle. The resultant solid product was sifted using a sterilized stainless steel sieve to obtain 150μm-sized microparticles. Lastly, the powder was stored in air-tight wrapped crucibles inside a desiccator.
