Application of Modified Fe₃O₄ Nanocomposites for Dye Removal: Equilibrium, Kinetic, and Thermodyanmic Study

Abstract

Numerous authors prepared Fe3O4 magnetite for different applications, but still Fe3O4 magnetite encourages investigators for new ideas due to its superior physical and chemical properties, which have excellent implications in various fields. In the past several decades, Fe3O4 magnetite has played an important role in wastewater treatment. There are growing appeals for surface-modified Fe3O4 magnetite due to high affinity of modified nanoparticles (NPs) toward contaminants. In this study, a chemical coprecipitation method was applied to synthesize the Fe3O4 NPs. The scanning electron microscopy (SEM) images of the Fe3O4 NPs (uncoated or free) revealed the agglomeration of the magnetite (Fe3O4) particles. But the horseradish peroxidase enzyme (HRP) and activated carbon-coated (ACC) Fe3O4 oxide exhibited homogeneous distribution of particles with relatively less agglomerate of the particles. In this work, the adsorption potential of free-Fe3O4, HRP-Fe3O4, and ACC-Fe3O4 were explored for removal of acid violet 17 (AV 17), rhodamine B (RhB), Congo red (CR), and methylene blue (MB) from aqueous solutions. The present work highlights the synthesis techniques, modification, and characterization of prepared NPs using SEM, x-ray defractometry (XRD), and Fourier transform infrared (FTIR). In addition, this study covers adsorption equilibrium isotherms, kinetics, thermodynamics, and future applications. At optimum operating conditions, 60% AV 17, 78% RhB, 85% CR, and 90.62% MB removed using free-Fe3O4. Similarly, in the case of HRP-Fe3O4, 90% AV 17, 92% RhB, 98% MB, and 99% CR removed successfully. While in the case of ACC-Fe3O4, 93% AV 17 and >98% RhB, MB, and CR dyes were removed. The Langmuir adsorption capacity obtained in the present study is 19.6, 35.2, and 37 mg/L for AV 17; 31, 42, and 47 mg/g for RhB; 45.4, 50, and 52 mg/g for CR; and 35.4, 47.1, and 49.2 for MB, obtained using free-Fe3O4, HRP-Fe3O4, and ACC-Fe3O4 nanoparticles, respectively. The obtained results suggest that the data are in fit with the Langmuir model for all the dyes. Kinetic and thermodynamic studies signifying that the present adsorption process is feasible with spontaneous as well as endothermic. The prepared green magnetite nanoparticles could be use in different application due to their magnetic property.