Batch adsorption of methyl orange dye from solutions using nano-magnetic Fe/Mn-modified activated carbon derived from lignocellulosic biomass: Kinetics and thermodynamics

Recently, water pollution with dyes is one of the most serious problems and the most dangerous to human health and living organisms. This study involves the synthesis of magnetic nano form of Fe-Mn binary oxide modified biomass derived of agricultural waste commercial (wood shavings) as a raw material. Magnetic nanoparticles were prepared from activated carbon obtained from lignocellulose through chemical activation of wood shavings using NaOH incorporated with (FeCl3.6H2O), ferrous sulphate heptahydrate (FeSO4.7H2O) and potassium permanganate (KMnO4) for effective removal of MO dye from aqueous solutions in a batch processes. This material was characterized through several advanced techniques such as Fourier transform infrared Spectroscopy (FTIR), X-ray diffraction (XRD), Field Emission Scanning Electron Microscopy (FE-SEM), Thermo gravimetric analysis (TGA), Energy -dispersive X-ray spectroscopy (EDS), Transmission electron Microscopy (TEM) and Vibration sample magnetometer (VSM). These analysis techniques highlighted the successful synthesis of magnetic nanocomposite with a porous structure. Batch adsorption experiments were studied by including contact time, adsorbent dose, pH, and temperature to determine the optimal conditions for maximum dye removal efficiency. The developed LB-Fe/Mn nanocomposite demonstrated excellent removal efficiency (98.16%) for methyl orange, outperforming many current advanced materials. Thermodynamic study revealed the endothermic and spontaneous nature of studied process. Adsorption kinetics followed a pseudo-second-order model (R² = 0.9676), while Freundlich (R² = 0.9544) and Temkin (R² = 0.9545) isotherms best described the equilibrium data, indicating multilayer adsorption on heterogeneous surfaces with abundant binding sites.