Acidic ionic liquid-based liposome for efficient catalytic degradation of azo dyes

Abstract

Amphiphilic ionic liquids (ILs) with an imidazole head and two undecene tails (abbreviated as [MimV11, V11]Br) were synthesized through alkylation reaction. They were utilized as lipoid monomers for constructing an isotropic catalytic degradation platform of azo dyes. The spherical structure of this IL-based liposome was reinforced by cross-linking polymerization of the olefin tails. The imidazole groups served as anchor points for attaching catalytic heteropolyanions (such as [PW12O40]3-, [PMo12O40]3-) to the liposomal vehicle. Furthermore, the arrangement of these linkers on the liposome surface facilitated the trapping and enrichment of the catalytic species. Consequently, a series of isotropic catalysts decorated with heteropolyanions (poly[MimA11, A11][heteropolyanions]) were prepared through anion exchange, where sufficiently exposed heteropolyanions maximized the catalytic degradation activity. The morphology, structure, and properties of the catalysts were confirmed using SEM, TEM, FTIR, XPS, UV–vis, and GC–MS. Experimental results found that poly[MimA11, A11][PW12O40] was the optimal catalyst, achieving a removal efficiency of 97.2% for methyl orange (MO) within 3 h. The intermediates involved in the reaction were analyzed to propose the degradation pathway of MO. Moreover, this kind of solid catalyst could be recovered by centrifugation, and its degradation efficiency remained above 91% even after five cycles. This research provides valuable insights for expanding the applications of IL-functionalized materials.