Manufacturing a Supercritical Carbon Dioxide Dryer and its Application for Production of Nickel (II) Oxide Aerogel

In this research, a simple supercritical carbon dioxide dryer was designed and constructed for the production of various aerogels. The most significant advantage of the constructed device was its automatic heating and cooling system, which allowed better control of the operational conditions during the drying process and the production of nanostructured materials with increased porosity. The constructed device had the capability to operate in a temperature range of 5°C to 90°C and pressures up to 140 bar. To evaluate the performance of the constructed device, nickel oxide (II) gel was synthesized using the sol-gel method and dried using the supercritical carbon dioxide drying method. The prepared aerogel was calcined at a temperature of 300°C for 2 hours. The physical and chemical characteristics of the nickel oxide aerogel were examined using X-ray diffraction (XRD) analysis, Brunauer-Emmett-Teller (BET) nitrogen adsorption and desorption, and field emission scanning electron microscopy (FESEM). The results indicated that the nickel oxide aerogel had an open porous structure and was composed of spherical nanoparticles. The synthesized aerogel had a specific surface area of 167 m²/g, pore volume of 0.61 cm³/g, average pore diameter of 6.14 nm, and average crystallite size of 6.4 nm. The obtained results demonstrated that drying nickel oxide nanostructures using the constructed supercritical carbon dioxide dryer led to better preservation of its porous structure.