Synthesis of nanostructured high specific surface area iron (III) oxide using a home-made supercritical carbon dioxide dryer

This study aimed to produce nanostructured iron (III) oxide with a high surface area and high porosity. Iron (III) oxide was synthesized using the sol-gel method. The resulting gels were dried using two different methods, i.e., ambient drying (at 80 oC) and supercritical carbon dioxide drying. The produced iron oxide aerogel and xerogel were then calcined at 350 oC for 4 hours. The physico-chemical properties of the iron (III) oxide nanostructures were investigated using X-ray diffraction (XRD), nitrogen adsorption-desorption, and field emission scanning electron microscopy (FE-SEM) analyses. The results showed that the iron (III) oxide aerogel consisted of spherical nanoparticles. The X-ray diffraction pattern demonstrated the aerogel had a crystalline phase of pure hematite (α-Fe2O3). In addition, the produced aerogel had a specific surface area of 140 m2/g, the volume of porosities was 0.32 cm3/g, and the average diameter of pores was 8.9 nm. The produced xerogel also had a specific surface area of 65 m2/g, a volume of porosities of 0.18 cm3/g, and an average pore diameter of 10.8 nm. Therefore, the results of BET analysis confirmed that drying of iron oxide nanostructures using the supercritical drying method can lead to better preservation of its porous structure.