Removal of Crystal violet Dye from Aqueous Solution Using Surfactant Modified NiFe2O4 as Nanoadsorbent; Isotherms, Thermodynamics and kinetics Studies

The removal of crystal violet from aqueous solution by NiFe2O4 magnetic nanoparticles treated with sodium dodecyl sulfate was investigated. The modified magnetic nanoparticles were prepared by chemical reaction of a mixture of Ni+2 and Fe+3 ions mixture in aqueous solution in the presence of ammonia and then sodium dodecyl sulfate was utilized as an ionic surfactant to modify the obtained magnetic nanoparticles. The morphologies of synthesized magnetic nanoparticles were characterized by electron microscopy techniques. The X–ray diffraction results confirmed the formation of magnetic nanoparticles with face centered cubic structure and the crystallite size was found to be 19 nm. The Fourier transform infrared spectrums confirmed the coating of sodium dodecyl sulfate on synthesized magnetic nanoparticles. The effects of different parameters, such as pH, initial concentration of the dye and contact time were studied on the adsorption of crystal violet onto modified magnetic nanoparticles. The equilibrium data of dye adsorption were well fitted to the Freundlich adsorption isotherm. Adsorption kinetics was accommodated by a pseudo–second–order model and the results, obtained from Boyd plot indicated that the crystal violet adsorption onto modified magnetic nanoparticles was controlled by film diffusion. Thermodynamic parameters, such as changes in Gibbs free energy, enthalpy, and entropy were also determined. The calculated activation energy suggested physical adsorption of dye onto synthesized magnetic nanoparticles.