“…Then added 6 M NaOH solution until alkaline to separate the impurities. After that, it was calcined at 750 °C for 4 hours to obtain alumina then characterized by FTIR (Ramdhani, Yanuar, Zulkifli, & Sarwana, 2018). CaO had been prepared from golden snail shells and used by previous research (Rodiah, Erviana, Rahman, & Budaya, 2020).…”