CoFe₂O₄/PANI/MWCNTs ternary hybrid composites. Synthesis, characterization, the effect of MWCNTs ratio and dye...

We have synthesized cobalt ferrite (CoFe₂O₄) using the sucrose auto-combustion method and subsequently employed the in situ polymerization technique to fabricate ternary composites comprising CoFe₂O₄, polyaniline (PANI), and multi-walled carbon nanotubes (MWCNTs). In this novel investigation, we explored the influence of varying MWCNTs ratios on these composites' structural, magnetic, thermal, and electrical properties. The crystal structures of the synthesized composites were analyzed using X-ray diffraction (XRD), while Fourier transform infrared (FT-IR) spectroscopy revealed changes in bonding patterns, including the disappearance of ferrite bonds and the emergence of new ones. Transmission electron microscopy (TEM) images illustrated a complete coating of PANI on both MWCNTs and CoFe₂O₄ particles, resulting in a substantial reduction in magnetization compared to pure CoFe₂O₄ ferrite due to PANI's nonmagnetic nature. Vibrating sample magnetometer (VSM) measurements confirmed this reduction, indicating a decrease to 7.3 emu.g^-1. Thermal analysis demonstrated an enhancement in thermal stability with increasing MWCNTs content, as evidenced by an increase in the temperature equivalent for half decomposition (T₅₀) from 486 to 522 °C for composites with 40% MWCNTs. Moreover, the electrical conductivity showed a corresponding rise with MWCNTs content, increasing from 3.1 × 10^-3 Ω^-1.cm^-1 to 2.2 × 10^-2 Ω^-1.cm^-1, possibly indicating charge transfer from PANI to MWCNTs. To assess practical applications, we investigated the ability of the composite with 40% MWCNTs to remove phenol red (PR) dye from aqueous solutions. Through a systematic study of adsorption parameters and kinetics, we determined optimal conditions for effective dye removal and elucidated the underlying adsorption mechanism. Our results demonstrated the composite's efficiency in dye removal, with a 6.4 mg·g^-1 capacity for PR dye, highlighting its potential for environmental remediation efforts.