Synthesis, analysis, and multi-faceted applications of solid wastes-derived silica nanoparticles: a comprehensive...

The synthesis of silica nanoparticles (SiNPs) has emerged as an extensive area of research in the last century. Owing to their instinctive properties like modifiable mesoporous structure, high surface area, adjustable pore size, and pore volume, SiNPs could be utilized in numerous fields like chemical, biochemical, catalysis, adsorption, and pollution control. Conventionally, SiNPs are produced by tetraethylorthosilicate (TEOS), tetramethylorthosilicate (TMOS), and sodium silicate, which are toxic and expensive. Therefore, the development of green, cost-effective approaches for the synthesis of SiNPs is highly desirable. In this course, during the last decade, silica-rich solid wastes (rice husk, corn cob, sugarcane bagasse, palm ash, fly ash, waste glass, waste packaging materials, photonic industrial wastes, etc.) were acknowledged as economical precursors to produce green SiNPs. In this respect, the present review focuses on reviewing several solid waste materials used for the synthesis of SiNPs, their properties, and different characterization techniques used for the analysis of SiNPs. The present review also accounts for the potential applications of such green SiNPs in several fields like catalysis, adsorption, biomedical applications, and energy storage. Moreover, despite the potential applications of SiNPs, still there is a lot to explore about their synthesis and utilization. Hence, in the last section of this review, future scope, challenges, and risk assessment of SiNPs have been discussed.