Efficient removal of Methyl orange dye via a MnFe₂O₄/GO nanocomposite with a CTAB dual-layer surfactant coating

This study investigated the adsorption of methyl orange (MO) from aqueous solutions using a novel MnFe₂O₄/GO nanocomposite coated with cetyltrimethylammonium bromide (CTAB). The dual-layer surfactant modification facilitates both electrostatic and lipophilic interactions. This enhancement significantly improves dye removal efficiency. The adsorption process was monitored using spectrophotometry at 464 nm, with various characterization techniques confirming the structural and magnetic properties of the nanocomposite. The optimized parameters for maximum adsorption include a 2-minute ultrasonic dispersion, pH 6.8, and a surfactant-to-adsorbent ratio of 1, achieving a maximum adsorption capacity of 285.7 mg/g. The kinetic data followed a pseudo-second-order model, whereas the adsorption isotherm aligned with the Freundlich model, indicating multilayer adsorption. Thermodynamic analysis revealed the spontaneous and exothermic nature of the process. Additionally, the magnetic properties of the nanocomposite enabled efficient separation and reusability over three cycles without significant loss of performance. This study demonstrates the potential of MnFe₂O₄/GO coated with CTAB for rapid, efficient, and reusable removal of anionic dyes from wastewater through a combined mechanism of electrostatic and hydrophobic interactions.