Adsorption of methylene blue onto size controlled magnetite nanoparticles

Methylene blue (MB) is an extremely toxic compound and so is hazardous to the environment. The presence of MB in water can cause cancer, provide an optimum environment for bacterial growth, oxidize red blood cells and results mental disorder. In this study, we have used magnetite nanoparticles (MNPs) for the removal of MB from aqueous solution. The MNPs were prepared by microemulsion assisted co-precipitation method at pH 10, 11 and 12. The adsorption study was performed at 298 and 308 K. The MNPs were characterized by using Brunner Emmet Teller (BET) surface area, X-rays diffraction (XRD), Transmission electron microscopy (TEM) and Fourier transform infrared (FTIR) spectroscopy. The batch tests were performed to study the uptake of MB from aqueous solution. The effect of concentration and temperature for the removal of adsorbate were also investigated. The maximum adsorption of 185.5 mg g^-1 was calculated for the MNPs synthesized at pH 10. This can be associated to the high surface area and availability of more active sites as compared to the MNPs synthesized at pH 11 and 12. The sorption study confirmed that the adsorption efficiency increases with increase in temperature which infers that the process is endothermic. The Langmuir adsorption model was found well fitted to the data confirming the monolayer adsorption of dye molecules onto MNPs.