Exploring enhanced gas-phase toluene adsorption by engineered a novel magnetic nanoadsorbent modified with p-aminobenzoic acid: Insights on characterization, performance, kinetics, isotherm, mechanism and reusability

Abstract

In this study, a novel magnetic nanoadsorbent (MNA), Fe3O4@SiO2 functionalized with p-aminobenzoic acid (p-AMBA), was prepared, characterized, and assessed for its efficiency in removing gas-phase toluene, a volatile organic compound (VOC). The Fe3O4, Fe3O4@SiO2, and Fe3O4@SiO2@p-AMBA MNAs were prepared and subjected to comprehensive analysis using techniques such as FTIR, SEM, EDX, VSM, XRD, TGA and BET to clearly reveal their properties through detailed characterization. Adsorption studies revealed that the Fe3O4@SiO2@p-AMBA exhibited the highest capacity, with an adsorption value of 555 mg/g for toluene, compared to 188 mg/g for Fe3O4 and 321 mg/g for Fe3O4@SiO2. The modification with p-AMBA significantly improved the adsorption performance of the material. Kinetic and isotherm models indicated that the adsorption process is best described by the pseudo-2nd-order kinetic model and by the Dubinin-Radushkevich isotherm model, suggesting both physical and chemical adsorption mechanisms. Furthermore, the reusability and adsorption stability performance of the MNAs was evaluated. The MNAs continued exhibiting excellent adsorption, with reuse efficiencies of 83 % (corresponding to 158 mg/g) for Fe3O4, 86 % (corresponding to 279 mg/g) for Fe3O4@SiO2, and 87 % (corresponding to 486 mg/g) for Fe3O4@SiO2@p-AMBA after five consecutive cycles, indicating superior structural and regeneration abilities. The results highlight the significant effect of surface modification on adsorption efficiency, positioning Fe3O4@SiO2@p-AMBA as a promising material for VOC removal and air pollution control. This work highlights the importance of developing sustainable materials to address environmental challenges.