High‐Purity Template‐Free Mesoporous Silica Synthesized FROM Coal Fly Ash

Abstract

The study demonstrates a new method to create high‐purity mesoporous silica from coal fly ash without using structure‐directing agents. Divided into two stages, the process involves pre‐treating the ash with Na2CO3, calcination, cooling, washing, and drying to yield a dehydrated sample. Subsequently, silica synthesis occurs through an acid refluxing technique using thermally activated coal fly ash with Na2CO3. Key factors impacting synthesis include acid content and liquid‐to‐solid ratio. The study extensively employs various characterization methods like XRF, XRD, FTIR, and BET analysis, revealing a 99.1 % purity in silica content, a surface area of 793.51 m2/g, and a pore size of 3.9 nm. Optimal conditions for this synthesis involve 80 °C temperature, 2‐hour reaction time, 25 % hydrochloric acid concentration, and a 10 : 1 liquid‐to‐solid ratio. FTIR spectra demonstrate similarities between the obtained silica and commercial Sigma Aldrich silica. This innovative approach presents a promising avenue for generating top‐quality silica from coal fly ash, potentially diversifying applications across industries reliant on high‐performance silica materials.