Non-aqueous modification of synthesized hematite nanoparticles with oleic acid

A process for non-aqueous surface modification of synthesized hematite nanoparticles is presented in this paper. Oleic acid was successfully grafted onto a hematite nanoparticle surface in methanol. The FTIR results demonstrated that chemical bonding formed between oleic acid and the hematite surface. Further studies indicated that the binding mechanism between the oleic acid and the hematite surface caused monodentate interaction. The grafted density of oleic acid onto the hematite surface increased linearly at the beginning with oleic acid concentration in the treatment solution and then leveled off at high oleic acid concentration. The saturated grafted density was 2.94 mmol/m2. As more oleic acid was grafted onto the hematite surface, the hydrophobicity of the hematite nanoparticle changed from hydrophilic to hydrophobic.