Effectively removing radioactive iodine from the environment is critical for mitigating the risks associated with nuclear accidents. The activated carbon of eggshell (ESAC) was composited with MgO and Fe3O4nanoparticle (ESAC@Fe3O4 and ESAC@MgO@Fe3O4) by a simple method and used as a recyclable and effective adsorbent for the removal of iodine in cyclohexane. A full analysis using SEM, EDS, FTIR, XRD, BET, and TEM, showed that the Adsorbents utilized were successfully made. The value of Brunauer–Emmett–Teller (BET) surface area for ESAC, ESAC@MgO@Fe3O4 and ESAC@Fe3O4 was obtained 2.39,   12.35 and 43.31 m2·g-1 respectively. The optimal adsorption conditions, including initial the amount of adsorbents utilized (0.12 g/10 ml), and contact time (8h) for ESAC@Fe3O4 and 16 hours for both ESAC and ESAC@MgO@Fe3O4 were determined. The adsorption process data matched well with pseudo-first-order and Langmuir isotherm models. The adsorption behavior followed the pseudo-first-order kinetic model and conformed to Langmuir and Redlich–Peterson isotherms, indicating monolayer and heterogeneous surface adsorption. The intraparticle diffusion model showed that pore diffusion was not the sole rate-limiting step. Furthermore, the maximum adsorption capacity of the ESAC, ESAC@MgO@Fe3O4 and ESAC/Fe3O4 magnetic composite toward iodine reached as high as 157.97 mg·g-1, 222.89 and 324.89 mg·g-1, respectively. Finally, the adsorbents also exhibited excellent regeneration performance over five cycles. These findings demonstrate, for the first time, the synergistic effect of dual metal oxide functionalization of bio-waste-derived carbon for efficient iodine removal in organic-phase systems, offering a scalable, low-cost, and environmentally sustainable solution for radioactive waste treatment.​