Highly efficient removal of dibutyl phthalate from wastewater using a novel hydrophilic–lipophilic magnetic adsorbent based on silica-coated iron oxide nanoparticles

The widespread occurrence of dibutyl phthalate (DBP) in aquatic systems demands effective remediation approaches. This study developed a novel magnetic adsorbent (Fe₃O₄@SiO₂-R) through the surface functionalization of silica-coated iron oxide nanoparticles with octadecyl silane and (3-aminopropyl)trimethoxy silane (APTMS) to incorporate both hydrophobic and hydrophilic groups. Comprehensive characterization (SEM, XRD, FTIR, XPS) confirmed the successful synthesis of the adsorbent. Batch adsorption experiments systematically evaluated the DBP removal across different water matrices (river water, municipal and industrial wastewater), examining the effect of concentration, contact time, adsorbent dose, and pH effects. The adsorbent demonstrated exceptional performance with a maximum adsorption capacity of 645.43 mg g^-1 and removal efficiencies of 98.4%, 94.2%, and 88.7% in the respective matrices, reducing DBP to <6 μg L^-1. The process simultaneously decreased the total organic content (TOC) by 18% and chemical oxygen demand (COD) by 22%, indicating effective co-removal of the organic pollutants. Adsorption followed the Langmuir isotherm (<i>R</i> ² = 0.994) and pseudo-second-order kinetics, suggesting monolayer chemisorption. Remarkably, after 30 reuse cycles, the removal efficiency decreased by only 20%, demonstrating excellent reusability. Comparative analysis revealed that the adsorbent outperformed many existing materials in terms of adsorption capacity and operational simplicity. These findings highlight Fe₃O₄@SiO₂-R as an efficient adsorbent for plasticizer removal, with significant potential for practical water treatment applications while supporting SDG targets for clean water.