High-Efficiency Adsorption Removal of Congo Red Dye from Water Using Magnetic NiFe₂O₄ Nanofibers: An Efficient...

The pollution caused by organic dyes in water bodies has become a major environmental issue, and removing such pernicious dyes presents an immense challenge for the scientific community and governments. In this study, a sorbent based on nickel ferrite (NiFe₂O₄) fibers was fabricated by the solution blow spinning (SBS) method for the adsorptive removal of anionic Cong red (CR) dye. The cubic-spinel structure and the magnetic and porous nature of NiFe₂O₄ were confirmed by XRD, magnetometry, BET, and SEM analyses. The saturation magnetization confirmed the magnetic nature of the fibers, which favorably respond to an external magnetic field, facilitating separation from a treated solution. The sorption kinetics of CR on NiFe₂O₄ were best described by the pseudo-second-order model, while sorption equilibrium agreed best with the Freundlich, Langmuir, Sips, and Temkin isotherm models, suggesting a complex mechanism involving chemisorption, monolayer coverage, and heterogeneous adsorption. The NiFe₂O₄ fibers annealed at 500 °C showed a high CR removal efficiency of ~97% after only 30 min. The sorbent's porous structure and high specific surface area were responsible for the improved removal efficiency. Finally, the results indicated the potential of the NiFe₂O₄ fibers in the remediation of water contaminated with Congo red dye.