Effect of Aging Solvents on Physicochemical and Thermal Properties of Silica Xerogels Derived from Steel Slag

Silica xerogels were synthesized from steel slag by sol-gel method with ambient pressure drying. Effect of aging solvents (methanol, ethanol, n-propanol and isopropanol) on properties of silica xerogels was investigated. Formation of amorphous structure and silica network of silica xerogels was confirmed by X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy analysis, respectively. Field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) analyses revealed highly porous structure silica xerogel aged in isopropanol. Specific surface area and pore volume of silica xerogels increased in the order: n-propanol < ethanol < methanol < isopropanol. Specific surface area of silica xerogel aged in isopropanol was 481 m(2) g(-1). Thermogravimetric analysis (TGA) and differential thermal analysis (DTA) presented that highest thermal stability of silica xerogel was obtained in the presence of methanol. Lowest thermal conductivity and bulk density were specified with isopropanol as 0.046 g cm(-3) and 0.036 W m(-1) K-1.