Green and Effective Magnetic Solid‐Phase Extraction to Remove Oil From Seawater Using Fe ₃ O ₄ Nanoparticles Anchored on Biomass and Agricultural Waste

Innovative adsorbent materials have been developed to meet the increasing demand for effective, environmentally friendly methods to remove oil from water sources. The main objectives of this study were to synthesize and characterize a nanocomposite containing Fe 3 O 4 nanoparticle–impregnated biomass and alfalfa waste (Fe 3 O 4 @BioAW). Coprecipitation and impregnation methods were combined to produce the nanocomposite, thereby enhancing the capacity of the biomass/alfalfa adsorbent for oil adsorption. Comprehensive characterization, including FTIR, XRD, and SEM, enabled the examination of the adsorbent’s morphological and structural properties. The material exhibited a high oil adsorption capacity of 6.671 g/g (removal efficiency of 87.03%) at pH = 5.0 in adsorption studies using a simulated oil–water system with the Fe 3 O 4 @BioAW adsorbent. The adsorption equilibrium data were well described by the Langmuir isotherm model ( R 2 = 0.9394; R L = 0.07). The pseudo‐second‐order kinetic model fit the data reasonably well ( R 2 = 0.9953). This study demonstrates the effective use of alfalfa‐based biomass combined with magnetic Fe 3 O 4 nanoparticles for efficient oil removal and facile recovery and reuse, highlighting its potential for environmental remediation and wastewater treatment.