<p>Graphite-based adsorbents provide a sustainable and eco-friendly alternative to conventional metal-based adsorbents, yet their performance in removing pharmaceutical pollutants remains underexplored. In this study, a phenylboronic acid-functionalized magnetic expanded graphite (EG/Fe₃O₄-PBA) nanocomposite was developed as a novel adsorbent for the treatment of acetaminophen (ACT)-contaminated hospital wastewater. The functionalization endowed the composite with a porous structure, rapid magnetic separation, and strong affinity toward ACT molecules. The experiments were designed using a central composite design (CCD) and analyzed with response surface methodology (RSM) to assess the combined influence of operational parameters on adsorption performance and to optimize conditions for maximizing ACT removal efficiency. Adsorption behavior was systematically investigated through isotherm, kinetic, and thermodynamic studies. The equilibrium data fitted well to the Langmuir model, confirming monolayer adsorption with a high maximum capacity of 451.30 mg g⁻¹ achieved within 20&#xa0;min. Kinetic analysis revealed that the process followed the pseudo-second-order model, highlighting chemisorption as the main mechanism. Thermodynamic evaluation showed negative Gibbs free energy values (–1.21 to − 15.67&#xa0;kJ mol⁻¹), a positive enthalpy change (100.6&#xa0;kJ mol⁻¹), and a positive entropy change (360.3&#xa0;J mol⁻¹ K⁻¹), confirming that adsorption was feasible, spontaneous, and endothermic. The nanocomposite also exhibited excellent reusability, maintaining 80.5% efficiency over seven adsorption-desorption cycles with only a minor decline from the initial 98.8%. These findings demonstrate that EG/Fe₃O₄-PBA combines high adsorption capacity, rapid removal efficiency, and good recyclability with environmental compatibility. This work highlights the significance of functionalized graphite-based nanocomposites as a promising and sustainable solution for the treatment of pharmaceutical-contaminated wastewater.</p>