Fabrication of a Fe3O4/CS/AgNPs Composite from Indigenous Iron Sand for Enhanced Methylene Blue Adsorption

Abstract

In this study, magnetite (Fe₃O₄) material was synthesized from natural iron sand and subsequently augmented with chitosan/silver nanoparticles (Fe₃O₄/CS/AgNPs) to serve as a methylene blue (MB) adsorbent. The Fe₃O₄/CS/AgNPs composite was prepared via co-precipitation method and confirmed by X-ray diffraction (XRD), vibrating sample magnetometry (VSM), Fourier transform infrared spectroscopy (FTIR), and field emission-scanning electron microscopy (FE-SEM). FE-SEM images revealed that Fe₃O₄ and Fe₃O₄/CS/AgNPs composites were octahedron and oval-shaped, respectively, with Ag particles evenly dispersed across the Fe₃O₄/CS surface. The VSM data disclosed that the saturation magnetization for the Fe₃O₄/CS/AgNPs adsorbent was 21.36 emu/g, and it could be effortlessly separated from the solution with the help of an external magnet. The kinetics and adsorption isotherms data for MB on the Fe₃O₄/CS/AgNPs composite correspond well with the pseudo-second-order kinetic model and Langmuir isotherm model. The maximum adsorption capacity for MB on the Fe₃O₄/CS/AgNPs adsorbent was 74.63 mg/g, and the percentage removal of MB could be maintained at 70.4% after five cycles of repetition. Overall, the Fe₃O₄/CS/AgNPs composite shows promise as a reliable adsorbent for eliminating MB from environments.