Recent trends in the use of silica-based materials and their composites in extraction techniques: A review

The application of silica-based materials (SBMs) such as silica nanoparticles (SiO2-NPs) and silica materials with mesoporous structures (for instance, MCM-48, SBA-15, and MCM-41) in analytical chemistry has caused huge consideration. Particularly, applying those materials in sorbent-based sorptive extraction/microextraction techniques has been in hotspots. SBMs have useful possessions such as modifying capability, high adsorption capacity, stability, and surface area. Therefore, SBMs have been broadly applied in various extraction procedures as sorbents. Respecting the attributes and advantages of SBMs, this article aims to assess the latest development and utilization of these materials in extraction techniques. This article is comprehensive in its scope, especially (a) SBMs and their properties are illustrated; (b) green synthesis of SBMs was investigated and discussed; (c) functionalized/modified SBMs (for instance, functionalized SBMs with deep eutectic solvents and ionic liquids) are investigated (d) different SBM composites (e.g, SBM-graphene, SBM-metal-organic framework, SBM-covalent organic framework, SBM-molecularly imprinted polymer, etc.); are reviewed; (e) applications of functionalized/ modified SBMs and SBM composites in different extraction techniques are studied; (f) possible mechanisms for pre-concentrating and extracting analytes using SBMs from different samples are surveyed; and (g) current developments and perspectives of SBMs in analytical extraction processes are discussed. In our view, this article is new, informative, and timely, and will be interesting to a broad range of readers. Moreover, the review will be helpful for analytical extractants to understand further SBMs, their different composites, and their utilizations in extraction techniques.