Synthesis of low-density TEOS based silica aerogel with large surface area and determination of its surface charge

Abstract

The aim of this study is to synthesis of silica aerogel by TEOS, H2O, isopropyl alcohol and n-heptane as solvent and catalyst solutions of HCl and NH4F by sol-gel method in different parameters including molar ratios of IAP/TEOS, Total H2O/TEOS ,TMCS/TEOS and CNH4F and concentration of NH4F in solutions. The density, porosity, and refractive index of products were determined and reported. Aging process and solvent exchange were performed using isopropyl alcohol and %11 volume percent of TMCS in heptane solution. All samples were dried at ambient pressure in oven at 60 and 170 oC temperature. The drying diagrams were plot for products. Produced amorphous silica aerogel had good transparence, low density of o.o566 g/cm3 and large surface area 802 m2/g. In addition, density, porosity, pore volume, and refractive index of all samples were determined and reported. Tests of BET, X-ray, SEM for determining of their structure were also performed. FTIR analysis results confirmed the surface modification of products. Surface charge of aerogel was determined and adsorptions of methyl orange, methylen orange, methyl blue and methylene blue on both at pH 1 and pH 7 using UV/Visible were carried out. The results showed that the adsorption is higher at low pH

Keywords

• silica aerogel
• teos
• isopropyl alcohol
• sol-gel
• ambient pressure drying