Author: M. Sehol, K. Kasmawati, N. Narsito, S. J. Santosa, J. Jumina, M.F. Rizki3 , S.P.A. Anggraini, M. Al Muttaqii, and B. Sardi

DOI: http://doi.org/10.31788/RJC.2026.1919586

Crab shell (Portunus pelagicus Linn.) waste, a by-product of the seafood industry, was utilised as a rawmaterial toproduce chitosan and its derivatives for selective adsorption of Cu(II) and Cd(II) in seawater. The preparationprocess involved deproteinization, demineralisation, and deacetylation, followed by structural modifications toobtain beads, phosphate, thiocyanate, molybdate, sulfate, glutaraldehyde-crosslinked, and thiourea chitosan. Characterisation using FTIR and XRD confirmed functional group transformation and crystallinity reductionassociated with deacetylation and chemical modifications. The degree of deacetylation (DD) was significantlyinfluenced by NaOH concentration, temperature, reflux time, and HCl concentration, with values reaching upto96%. Adsorption studies revealed that higher DD correlated with improved Cu(II) binding, particularly at pH5–6. Chitosan beads exhibited enhanced swelling and nearly doubled Cu(II) adsorption compared to powder. Amongthederivatives, glutaraldehyde-crosslinked and thiourea-modified chitosan showed the highest adsorption efficiencies(60.7% and 69.5%, respectively), indicating strong interactions with metal ions. These findings highlight thepotential of crab shell waste as a sustainable source of selective adsorbents for heavy metal removal in marineenvironments.

Keywords: Cd(II) Adsorption Chitosan Crab Shell; Cu(II) Adsorption; Seawater Treatment; Solid-PhaseExtraction