Investigation of the mechanism of establishing a solid–water–oil system by metastable droplets and their application in the fabrication of polyol nanosheets for rapid boron removal

The emulsion method is a typical way for the preparation of nanomaterials, however, it usually requires a lot of energy and surfactants to form and stabilize of emulsions. A critical factor limiting its application is to control the morphology of the material by modulating the size of the emulsion droplets. In this work, a novel solid-water–oil (S-W-O) system based on the integration of metastable emulsion and salt template method was proposed, and the functionalized silica nanosheets were prepared by the one-pot method. The size of the prepared nanosheets is relatively uniform, with a length of 800 to 1200 nm and a width of about 200 nm. Subsequently, a large number of epoxy group sites were introduced into the nanosheets relying on distillation precipitation polymerization, and the polyol groups were successfully loaded. Finally, the polyol-functionalized nanosheet adsorbent (NS@GMA-NMDG) was obtained and applied for the rapid removal of boron. NS@GMA-NMDG shows favorable adsorption performance for boric acid in solution, with a maximum adsorption capacity of about 35.49 mg g −1 based on the Langmuir model fitting and a fast adsorption rate of about 30 min to reach 96.3% of the adsorption equilibrium concentration. Remarkably, the investigation of the formation mechanism of nanosheets reveals that salt plays an important role in the S-W-O system. This study not only puts forward a novel method of designing and synthesizing nanosheet adsorbents, but also the application of surfactant-free and low-energy emulsification reflects the concepts of energy saving and clean production, which provides fresh inspirations for the development of new environmentally friendly adsorbents.