Synthesis and Characterization of Mesoporous Sodium Dodecyl Sulfate-Coated Magnetite Nanoparticles

Mesoporous magnetite nanoparticles are commonly used for biomedical and environmental applications. This can be attributed to their known magnetic properties and high surface area, the latter being a virtue of their nanometer-scale size. Applying coatings with various chemical functionalities to these nanoparticles increases their scope of application. Different organic and inorganic coatings have been explored. Sodium dodecyl sulfate (SDS) is a well-known surfactant that improves the surface properties of nanoparticles. This paper explores the in situ formation of SDS coatings on the surface of mesoporous magnetite nanoparticles prepared by means of a traditional co-precipitation method in air. Coatings made from solutions containing up to 2 wt% of SDS were investigated in respect of their composition, thermal characteristics, and magnetization by means of X-ray diffraction, infrared spectroscopy, thermogravimetric analysis and magnetic susceptibility. Adsorption isotherms and detailed morphology of the coated nanoparticles were also evaluated. Results showed that SDS forms multilayers together with water on the surfaces of the nanoparticles, where a maximum initial concentration of 0.5 wt% of SDS could be used to homogeneously coat the magnetite nanoparticles. At higher concentrations, SDS detaches from the nanoparticles surfaces.