Study of the Utilization of Heavy Metal Biosorption (Cr, Co, Cu, Fe, Cu, Mn, Ni) with Chitosan from Crab and Kupang Shell WasteAnnisa Fitri, Eka Eka, Tri Widya Edelwis and Hilfi PardiBIO Web Conf., 70 (2023) 02012DOI: https://doi.org/10.1051/bioconf/20237002012