Thermal Stability Analysis using Iron Oxide Nanoparticle Coated with SDS

The unique characteristic of iron oxide nanoparticles (IONPs) such as low toxicity, high coercivity, superparamagnetic, high magnetic susceptibility and high surface-to-volume ratio have created much attention in various field especially in the oil and gas sector. However, bare IONPs are easily to oxidize in air and tends to agglomerate due to the high surface energies between the nanoparticles. Therefore, surface coating is an essential step to maintain the stability of IONPs. In this research, IONPs were synthesized using facile co-precipitation method and surface coated with Sodium Dodecyl Sulphate (SDS) as ionic surfactant by the dip-coating method. Molar ratio of the coating agent was varied from 0.1 to 0.5 M and the calcination temperature after coating process was varied from 60⁰C to 606⁰C to study the effect on the crystallite size, degree of crystallinity and magnetite content of the coated IONPs. The coated IONPs were characterized using Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction device (XRD), and Thermogravimetric Analysis (TGA). The result has shown that at greater SDS to IONPs molar ratios, the crystalline size and crystallinity increased, while the magnetite content dropped. Higher calcination temperatures, however, resulted in larger sized crystals with less crystallinity and magnetite concentration. The TGA plot showed that more stable nanoparticles will be produced at higher calcination temperatures. Therefore, the ideal coating condition obtained is at molar ratio of 0.1 and calcination temperature of 154°C as it produces smallest crystallite size (8.56nm) and highest magnetite content (56.8%).