Synthesis and Characterization of Modified Silica Gel from Teff Straw Ash Using Sol-gel Method

Abstract

Teff straw ash was first converted into sodium silicate solution, then processed via sol-gel, producing low-density silica aerogel (modified silica gel). A one-step modification method was applied to produce modified silica gel from teff straw ash. The method involved the use of trimethylchlorosilane (TMCS), ethanol, and n-hexane as reagents, with a specific molar ratio. Then, we used ambient pressure drying to complete the process. The modified silica gel had improved properties compared to the unmodified one. These chemicals were used to modify the surface properties of the substrate. The surface of the modified silica gel used in the sol-gel method was altered with a TMCS solution. We studied how the properties of silica gel changed when we used different amounts of ethanol, n-hexane, and TMCS to modify it. Using BET, FTIR, XRD, and SEM, the properties of the porous structure of the modified silica gel were identified. The optimal molar ratio of pore (ethanol/TMCS/n-hexane) for modifying silica gel was found to be 25/25/100. This resulted in a modified silica gel with a specific surface area of 909.25 m2/g, a pore size of 0.5422 cm3/g, and a pore volume of 2.670 nm. The functional groups of the modified silica gel were verified by the FTIR analysis. The XRD analysis verified the amorphous and crystalline nature of the silica gel and the modified silica gel, respectively. The SEM images revealed the surface morphology of the modified silica gel.

Keywords

• Trimethyl chlorosilane
• Teff straw ash
• Silica gel
• Modified silica gel
• Synthesis