No abstract

Amino-functionalized silica-coated iron oxide (Fe3O4/SiO2 NH2/C18) magnetic nanoparticles were synthesized, and the amino-surface modification was performed by two different methods, a highpressure autoclave and reflux experiments. The nanoparticles were tested for their ability to remove naphthenic acids from a model crude oil solution and for their magnetic separation properties. Grafting degrees onto the nanoparticle surfaces of 3-aminopropyltrimethoxysilane (APTMS) and n-octadecyltriethoxysilane (ODS) were calculated based on elemental analysis and specific surface area of the nanoparticles was measured by the Brunauer, Emmett and Teller (BET) method. Presence of a core-shell structure of separate nanoparticles as well as nanoparticle agglomerates was confirmed by the use of transmission electron microscopy (TEM) imaging.Average nanoparticle size and coating thickness were calculated based on a TEM size distribution analysis. The two amino-functionalization methods revealed similar results for the adsorption of 4-heptylbenzoic acid (HBA) dissolved in octane, and 2.7 times higher adsorption capacity compared to the unmodified silica-coated (Fe3O4/SiO2) nanoparticles.