Removal of Heavy Metal Ions by using Calcium Carbonate Extracted from Starfish Treated by Protease and Amylase

CaCO3 extracted from starfish by using the commercial protein lyase having α-amylase, β-amylase, and protease is applied to remove heavy metal ions. The extracted CaCO3 shows excellent characteristics in removing heavy metal ions such as Cu2+, Cd2+, Pb2+, and Cr6+ compared with conventional materials such as crab shells, sawdust, and activated carbon except for removing Zn2+. SEM images reveal that the extracted CaCO33 has a good morphology and porosity. We characterize the removal efficiencies of the extracted CaCO3 for the heavy metal ions according to the concentrations, pH, temperatures, and conditions of empty bed contact times.