Development of a magnetite nanocomposite based on expanded graphite/chitosan for efficient removal of brilliant green dye from aqueous solutions

ABSTRACT

In this research, to develop an efficient and magnetic graphite-based nanocomposite (Fe₃O₄/EG-chitosan), the natural flake graphite was first expanded to improve its active surface area. The expanded graphite (EG) was then functionalized and magnetized with chitosan and Fe₃O₄ nanoparticles to increase its adsorption performance. Structure of EG/chitosan and nanocomposite Fe₃O₄/EG-chitosan were determined and confirmed by FT-IR, XRD, EDX, FESEM, VSM, zeta potential measurement and BET surface area measurements. The surface area of EG was improved from 10.13 to 83.08 m²/g after the functionalization of it using chitosan. Fe₃O₄/EG-chitosan exhibited a lower magnetization saturation value (30.9 emu/g) in compared with pure Fe₃O₄ NPs (60.2 emu/g). The fabricated nanocomposite was then applied to adsorb BG dye from aqueous media. The optimal removal of 98% BG dye was achieved at pH 8.0, adsorbent dosage 0.04 g, initial concentration 50 ppm, and temperature 293 K. The adsorption of BG is described well with the pseudo-second order kinetic model and the Freundlich isotherm model. The results also showed that the maximum adsorption capacity of BG dye was 21.8 mg/g using the Langmuir isotherm model. In addition, after 6 adsorption-desorption cycles, the adsorption capacity of the developed Fe₃O₄/EXG-chitosan toward BG remains high (90%).

KEYWORDS:

• Adsorption
• functionalized nanomaterial
• magnetic nanoadsorbent
• expanded graphite
• dye removal

Acknowledgments

The authors acknowledge the financial support from the Research Council of the University of Guilan for this research work.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Abbreviations

EXG, expanded graphite; CS, chitosan; BG, brilliant green; EP, epichlorohydrin; NPs, nanoparticles; FT-IR, Fourier transform infrared; XRD, X-ray diffraction; EDX, Energy-dispersive X-ray spectroscopy; BET, Brunauer-Emmett-Teller; FESEM, Field emission scanning electron microscopy.

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/01496395.2024.2358206