Abstract:
This study presents the successful preparation and evaluation of activated carbon derived from brown seaweed (Sargassum sp.) waste using chemical activation with zinc chloride (ZnCl₂) and thermal treatment. The resulting biosorbent was characterized by its iodine number, surface morphology, and adsorption efficiency for hexavalent chromium (Cr⁶⁺) ions in aqueous solutions. The activated carbons exhibited high microporosity, with iodine numbers reaching 290 mg/g at 800 °C, closely comparable to commercial activated carbon. SEM analysis revealed a porous surface structure, supporting its high adsorption capacity.
Batch adsorption experiments demonstrated that Cr⁶⁺ removal efficiency was strongly influenced by solution pH, initial ion concentration, and contact time. Optimal removal (>90%) was achieved at pH 2, low metal concentrations, and a contact time of 120 minutes. The bio-based activated carbon showed promising potential as a cost-effective and environmentally friendly material for heavy metal remediation. This approach contributes to sustainable waste valorization and supports circular economy practices.