Novel Approach to the Synthesis of Silica Gel: Sequential Mechanical Activation and Sol-Gel Methods from Fly Ash Derived from Coal

Exploration of unconventional resources and the reuse of industrial by-products are critical for advancing environmental sustainability. In this study, we propose a sequential mechano-activation and sol-gel method to synthesize silica gel (SG) from coal fly ash (CFA). The raw CFA used in this study contains 49.54% SiO2, with 99% of the particles measuring approximately 210 nm in size, as determined by XRF and Particle size analysis. Our findings indicate that the SG surface is rich in SiO- species, evidenced by the presence of silanol (Si-OH) and siloxane (Si-O) groups in FTIR and Raman analyses. XRD analysis confirmed the amorphous nature of the SG produced from CFA. Additionally, the SG obtained had a particle size of around 97 nm for 90% of the population. This work addresses the issue of coal waste management and provides promising material for wide application.