Enhanced dyes adsorption from wastewater via Fe3O4 nanoparticles functionalized activated carbon

Highlights: • A Fe₃O₄/activated carbon compound is achieved as a functionalized adsorbent. • The product has properties of efficient adsorption and rapid magnetic separation. • The synergistic interaction leads to additional porosity and enhanced adsorbability. • The key adsorption mechanisms include electrostatic attraction and mesoporous filling. • The adsorbent can be an environmental-friendly candidate for water treatment. -- Abstract: Fe₃O₄ nanoparticles functionalized activated carbon (Fe₃O₄/AC) as an adsorbent was prepared and used for fast and effectively removing rhodamine B (RhB) and methyl orange (MO) from aqueous solution. Its physical and chemical properties characterized indicate that the adsorbent possesses abundant surface functional groups, sensitive magnetic response and enhanced specific surface area. Batch experiments were carried out to investigate the adsorption capacity and mechanisms. The obtained experimental data fitted well with the general-order kinetic equation and Liu's isotherm model with a maximum adsorption capacity of 182.48 mg g⁻¹ for RhB and 150.35 mg g⁻¹ for MO, respectively. The thermodynamic parameter was analyzed further and it showed an exothermic and spontaneous adsorption process. This composite with high adsorption efficiency and rapid magnetic separation can be a promising and recyclable adsorbent for practical wastewater treatment and purification processes.