Abstract
Multifunctional pyridinium ionic liquids with different alkyl chain lengths were used as coating agents to prepare surface modified magnetite nanoparticles (MNPs/MIL). The synthesized nanoparticles were well characterized using Fourier transformation of infrared spectroscopy (FTIR), X-Ray diffraction (XRD), dynamic light scattering (DLS), energy dispersive X-ray analysis (EDX) and transmission electron micro-scopy (TEM) techniques to indicate that MNPs were successfully coated with multifunctional pyridinium ionic liquid (MIL) to control their particle size and surface charge. The positive surface charges on the MNPs/MIL, as indicated from zeta potential measurements, recommend their application as adsorbents for coomassie brilliant blue-R250 anionic dye (CBB) from aqueous solutions. The results indicated the high adsorption capacities of the surface modified magnetite nanoparticles that reached to 702 and 691 mg/g for magnetite nanoparticles coated with tetradecyl multifunctional pyridinium ionic liquids (TMIL) and hexadecyl multifunctional pyridinium ionic liquids (HMIL), respectively comparing with bare magnetite that only reached 84 mg/g. The equilibrium isotherm and kinetic parameters were evaluated and analyzed using different models to indicate that pseudo-second-order kinetic and the Freundlich iso-therm models were more suitable to describe the adsorption of CBB from aqueous solutions on Fe3O4/ HMIL and Fe3O4/TMIL. The adsorption mechanism was suggested to be through electrostatic interaction, pi-pi interactions, and H-bonding.
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