Fabrication of crosslinked chitosan-citrate/carbon nanotubes/Fe₃O₄ nanocomposite for effective adsorption of eosin Y...

This study aimed to develop an effective and magnetically separable chitosan-based nanocomposite adsorbent for efficient adsorption of anionic dye from aqueous solutions. Herein, a magnetic crosslinked chitosan-citrate/carbon nanotubes/iron oxide nanocomposite (CS-CT/CNT/Fe₃O₄) was developed for the effective removal of the anionic dye (eosin Y, ESY) from water. Characterization of the synthesized material was carried out via Brunauer-Emmett-Teller (BET) analysis, field emission scanning electron microscopy with energy-dispersive X-ray spectroscopy (FESEM-EDS), X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy (FTIR). The CS-CT/CNT/Fe₃O₄ nanocomposite exhibited a BET surface area of 11.63 m²/g, an average pore size of 19.35 nm, and a total pore volume of 0.0562 cm³/g. The adsorption process was optimized using a Box-Behnken design (BBD), focusing on three key parameters: adsorbent dosage (0.02-0.1 g), pH (4-10), and contact time (10-40 min). Optimization using the BBD model identified the optimal conditions of 0.086 g adsorbent dosage, pH 4, and 33 min contact time, under which the CS-CT/CNT/Fe₃O₄ nanocomposite achieved a maximum ESY removal efficiency of 94.57 %. Isotherm analysis revealed that the Langmuir and Freundlich models best described the equilibrium data. The maximum adsorption capacity of the CS-CT/CNT/Fe₃O₄ nanocomposite for ESY was found to be 420.6 mg/g. The underlying adsorption mechanisms of ESY dye were attributed to electrostatic interactions, hydrogen bonding, n-π interactions, and π-π stacking. These findings demonstrate the potential of the CS-CT/CNT/Fe₃O₄ nanocomposite as an efficient and versatile adsorbent for treating dye-laden industrial wastewater.