Iron oxide nanoparticles decorated oleic acid for high colloidal stability

<jats:title>Abstract</jats:title><jats:p>In the present study, oleic acid (<jats:styled-content style="fixed-case">OA</jats:styled-content>)‐decorated magnetite nanoparticles (<jats:styled-content style="fixed-case">MNP</jats:styled-content>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 <jats:styled-content style="fixed-case">OA</jats:styled-content> for improving the <jats:styled-content style="fixed-case">MNP</jats:styled-content>s colloidal stability. Based on our results obtained, it was found that the zeta potential values of <jats:styled-content style="fixed-case">MNP</jats:styled-content>s increased from −29.8 to −58.1 mV after modification of <jats:styled-content style="fixed-case">MNP</jats:styled-content>s with 1.2 wt.% of <jats:styled-content style="fixed-case">OA</jats:styled-content>. Indeed, results obtained clearly to show that a maximum colloidal stability of <jats:styled-content style="fixed-case">MNP</jats:styled-content>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 <jats:styled-content style="fixed-case">MNP</jats:styled-content>s sample (3 days). Based on vibrating sample magnetometer (<jats:styled-content style="fixed-case">VSM</jats:styled-content>) analysis, the resultant <jats:styled-content style="fixed-case">OA</jats:styled-content>‐decorated <jats:styled-content style="fixed-case">MNP</jats:styled-content>s exhibited superparamagnetic behavior with slightly lower saturation magnetization (51–69 emu/g) than that of undecorated <jats:styled-content style="fixed-case">MNP</jats:styled-content>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 <jats:styled-content style="fixed-case">OA</jats:styled-content>‐decorated <jats:styled-content style="fixed-case">MNP</jats:styled-content>s, which promoted the high colloidal stability performance.</jats:p>