Synthesis of funtionalized magnetic nanoparticles and usage in dyestuff adsorption

In this study, firstly superparamagnetic Fe3O4 nanoparticles were prepared by co-precipitation method. Secondly, these nanoparticles were covered with silica (SiO2) layer to protect them from oxidation by air and to prepare them ready for further functionalization. Finally, the amino groups were covalently grafted to the silica coated superparamagnetic Fe3O4 nanoparticles by using aminopropyl triethoxysilane (APTES) through silanization reaction. After being characterized by X-Ray Diffraction (XRD), Transmission Electron Microscopy (TEM), Scanning Electron Microscopy/Energy Dispersed X-Ray (SEM/EDX), Vibrational Sample Magnetometer (VSM), Zeta Potential and Fourier Transform Infra-Red Spectroscopy (FT-IR) techniques, the resultant material, Fe3O4@SiO2@NH2, was used for highly effective adsorption of two anionic dyes one of which is triarylmethane dye (Light Green, LG) and the other is azo dye (Brilliant Yellow, BY). The effects of adsorbent dosage, contact time, pH, temperature, and dye molecular structure on the adsorption were investigated. Acidic pH was better for both LG and BY. Adsorption was more favorable to some extent for LG in comparison with BY due to the contribution of stacking effect in addition to electrostatic attraction. Kinetic data demonstrated that the driving force for adsorption process could be explained by pseudo-second order mechanism in both systems. The equilibrium data were more compatible with Langmuir isotherm than those of Freundlich isotherm and the maximum adsorption capacities calculated for LG and BY at 30 0C and natural pH of the solution were 40,2 and 35,5mg/g, respectively. Thermodynamic calculations demonstrated that the adsorption process was spontaneous and exothermic. Fe3O4@SiO2@NH2 also showed good removal efficiency for both dyes at least over three cycles.