Modified silica xerogel from coal fly ash: the influence of D-Glucose and milling on structure and adsorption performance for Zn(II) and Rhodamine B

Silica-based materials hold great promise for environmental remediation, particularly in wastewater treatment. This study focuses on synthesizing silica xerogel from coal fly ash, modified through the addition of D-glucose as a porogenic agent and mechanical milling, to evaluate their impact on structural properties and adsorption performance. Fly ash from the Suralaya coal-fired power plant, containing 39.60% SiO2, was processed using the sol-gel method. Modifications included incorporating 30% D-glucose prior to gelation and calcination, and mechanical milling. XRD analysis showed the milled sample (SX-M) had the highest crystallinity (53.22%), while the unmodified (SX) and D-glucose-modified (SX-GC) xerogels remained largely amorphous. SEM and ImageJ analysis revealed that SX-GC had the smallest and most uniform particle size distribution (0.05–6.30 µm). Adsorption tests for Zn(II) ions showed over 99% efficiency, with SX-GC achieving the highest capacity at 89.90 mg/g. For Rhodamine B, SX-GC also showed the highest adsorption capacity of 77.11 mg/g at 350 ppm, with an optimal contact time of 60 minutes. These results highlight SX-GC as a promising, eco-friendly adsorbent for industrial wastewater treatment.