Converting industrial waste into valuable Zn2SiO4/SiO2 nanosheets for highly effective organic dye removal

As a common industrial waste, fly ash is conventionally used as a concrete additive, resulting in the wastage of silicon and aluminium materials and environmental pollution. In this study, we innovatively utilize fly ash waste to synthesize Zn2SiO4/SiO2 nanosheets, which are employed as effective adsorbents for purifying organic dyes such as methylene blue, rhodamine B, and congo red. The Zn2SiO4/SiO2 nanosheets, with a large specific surface area of approximately 81.21 m2 g−1, exhibit enhanced adsorption capacity for organic dyes, in contrast to pure fly ash with a specific surface area of only ~1.06 m2 g−1. Notably, the Zn2SiO4/SiO2 nanosheets demonstrate a remarkable adsorption capacity of 124.50 mg g−1 for methylene blue, which is ~120 times higher than pure fly ash. The adsorption kinetics are analyzed using Langmuir and Freundlich models, shedding light on the adsorption mechanism of the Zn2SiO4/SiO2 adsorbent. This study presents an efficient ‘waste-to-treasure’ approach, advocating for the secondary utilization of industrial waste to alleviate environmental pollution.