Iron oxide nanoparticles decorated oleic acid for high colloidal stability

Abstract

Abstract In the present study, oleic acid ( OA )‐decorated magnetite nanoparticles ( MNP s) were synthesized via in situ co‐precipitation method using ammonium hydroxide as a precipitating agent. This study aims to determine the optimum loading amount of OA for improving the MNP s colloidal stability. Based on our results obtained, it was found that the zeta potential values of MNP s increased from −29.8 to −58.1 mV after modification of MNP s with 1.2 wt.% of OA . Indeed, results obtained clearly to show that a maximum colloidal stability of MNP s in a basic medium could be significantly improved. As a result, this resultant colloidal suspension performance was approximately 7 times higher (21 days‐ high colloidal stability against precipitation and agglomeration) than that of the undecorated MNP s sample (3 days). Based on vibrating sample magnetometer ( VSM ) analysis, the resultant OA ‐decorated MNP s exhibited superparamagnetic behavior with slightly lower saturation magnetization (51–69 emu/g) than that of undecorated MNP s sample (80 emu/g) at room temperature. This behavior was attributed to the sufficient carboxylate ions from the outer layer of the bilayer of OA ‐decorated MNP s, which promoted the high colloidal stability performance.