Construction of ionic liquid-filled silica shell microcapsules based on emulsion template and evaluation of their adsorption properties toward 3,4,5-trichlorophenol after various surface functionalization

Abstract

The development of environmentally friendly and efficient methods for the removal of Phenolic endocrine disruptors (PEDs) from aqueous is essential to protect the environment and human health. In this work, sol–gel method and emulsion template approach were combined and applied to construct 1-Butyl-3-methylimidazolium hexafluorophosphate ([BMIM]PF6) ionic liquid-filled silica-shell microcapsules (SiO2@IL). And amino, halogen and long-chain alkanes surface-functionalized silica-shell encapsulated ionic liquid microcapsules (SiO2-NH2@IL, SiO2-Cl@IL, and SiO2-C16@IL) were successfully formulated by silica layer modification techniques. The microcapsules have homogeneous dimensions, about 1 µm, and high loading, about 92 wt% of ILs. Four microcapsules showed high adsorption properties and excellent regeneration performance for removing 3,4,5-trichlorophenol (3,4,5-TCP), which benefited from the excellent performance of [BMIM]PF6 on the extraction of 3,4,5-TCP and the enhanced hydrophobic and electrostatic effects of the surface modified microcapsules. The maximum adsorption capacity of SiO2@IL, SiO2-NH2@IL, SiO2-Cl@IL and SiO2-C16@IL calculated from the Langmuir model was 1047, 1207, 1108 and 1145 mg g−1 at 25 °C, respectively. The main factors affecting the extraction performance were the hydrophobicity and steric hindrance of [BMIM]PF6. After three regeneration cycles, the adsorption capacity and desorption efficiency of microcapsules were still above 90 %. The functionalization of the shell layer enhances the hydrophobic and electrostatic effects, which is conducive to the adsorption process, and provides some theoretical and data support for the subsequent construction of ionic liquid encapsulation materials for chlorophenol removal.