Document Type : Research Article
Iran University of Science and Technology
In this research, a simple supercritical carbon dioxide dryer was designed and built to produce aerogels. The most important advantage of this supercritical dryer is the automatic heating and cooling system, which helps to better control the operating conditions of the drying process and produce nanomaterials with higher porosities. This supercritical dryer is capable of operating in the temperature range of 5 to 90 oC and pressure above 140 bar. Nickel (II) oxide aerogel was synthesized using the sol-gel method. A green gel was formed by adding propylene oxide as a gelation agent to a solution containing ethanol and nickel chloride mineral salt and the resulting gel was dried by supercritical carbon dioxide. This aerogel was calcined at 300 oC for 2 hours. The structural properties of nickel oxide aerogel were investigated using X-ray diffraction (XRD), nitrogen uptake (BET), and field emission scanning electron microscopy (FESEM) analyzes. The results show that nickel oxide aerogel has a structure with open porosity and consists of cylindrical nanoparticles. This aerogel has a specific surface area of 167 m2/g, a pore volume of 0.61 cm3/g, an average pore diameter of 14.6 nm, and average crystal size is 4.6 nm.