Arc Plasma‐Synthesized Graphene Oxide From Coconut Fibers: A Green Adsorbent for Co‐60 and Cs‐137 Removal From Nuclear Liquid Waste

ABSTRACT The management of liquid radioactive waste (LRW) from nuclear facilities is challenging due to the persistence and toxicity of long‐lived radionuclides. This study reports an environmentally friendly synthesis of graphene oxide (GO) from coconut fiber biomass using a catalyst‐free arc plasma technique (> 3000°C), enabling complete carbon conversion and offering a sustainable pathway that leverages Indonesia's abundant biomass resources. The resulting GO was characterized by BET, FTIR, Raman, XRD, SEM, and HR‐TEM. BET characterization showed that the GO possessed an extensive surface area of 3302 m 2 /g with a highly developed porosity, whereas FTIR spectra verified the presence of oxygenated functional groups, including carboxyls, which facilitate ion‐exchange interactions. SEM and HR‐TEM showed uniform morphology and elemental composition dominated by carbon, oxygen, hydrogen, and trace potassium. Batch adsorption experiments with actual LRW from the G.A. Siwabessy reactor demonstrated high removal efficiencies, achieving 98.7% for Co‐60 and 75.6% for Cs‐137. The adsorption kinetics were consistent with a pseudo‐second‐order model, pointing to chemisorption as the dominant pathway, whereas the equilibrium data aligned with the Langmuir isotherm, yielding maximum uptake values of 249.047 MBq/g (Co‐60) and 151.016 MBq/g (Cs‐137). The findings highlight the promise of arc plasma‐derived GO as a green, high‐performance adsorbent for sustainable LRW remediation.