Effects of cetyltrimethylammonium bromide on the morphology of green synthesized Fe3O4 nanoparticles used to remove phosphate.

In this paper, iron oxide nanoparticles (IONPs) are successfully synthesized using Eucalyptus leaf extract in the presence of cetyltrimethylammonium bromide (CTAB) to enhance the dispersion and reduce aggregation of IONPs. CTAB was used as a stabilizing and capping agent in biosynthesis of IONP was observed. The particle size decreased from 183.9±30.1nm to 89.8±17.1nm as the concentration of CTAB increased from 0 to 0.4mM CTAB, indicating that CTAB reduce the aggregation of IONPs and enhance the reactivity. In addition, the removal efficiency of phosphate declined from 95.13% to 89.58% when the CTAB concentration increased from 0.4 to 10mM, indicating that a CTAB impacted on micelles and lipophilic biomolecules in Eucalyptus leaf extract, and hence affected the formation of IONPs. Furthermore, SEM image showed that the smaller spherical with some irregularly shaped CTAB-IONPs having a diameter of 80-90nm in the presence of 0.4mM CTAB were observed. The date from EDS, FTIR and TGA suggested that the CTAB capped on the surface of CTAB-IONPs, while XRD showed that zero-valent iron and iron oxide were formed. Finally, the formation mechanism of IONPs was proposed.