In this study, Fe3O4 nanoparticles impregnated onto corn cover were investigated as new composite sorbent for removing Alizarin Red S from aqueous solutions in a batch system. The main effective variables were examined on removal efficiency such as pH, sorbent dosage (m), and initial concentration of dye (Cd). Response surface methodology involving a Box–Behnken design for modeling the effective factors and their interactions was employed to optimize the removal percent (R%) of Alizarin Red S dye. The best conditions for the suggested model was found to be the maximum removal percent of dye in pH 2, Cd = 10 mg/L and m = 0.2 g. The kinetics, isotherm modeling, and thermodynamic studies of adsorption Alizarin Red S were conducted. A second-order kinetic model is favorable for the dynamic behavior of the adsorption process. Thermodynamic studies indicate that the adsorption system was spontaneous and exothermic. Moreover, the structure and morphology of nanocomposite sorbent were examined by means of X-ray diffraction, EDX analysis, and scanning electron microscopy. Beside, FT-IR analyses were performed to characterize the functional groups which were involved in the adsorption process.