Ionic Liquid-Based Catanionic Coacervates: Novel Microreactors for Membrane-Free Sequestration of Dyes and Curcumin

Abstract

Surfactant-mediated coacervates are termed as the new age microreactors for their ability to spontaneously sequester the molecules with varied polarities and functionalities. Efforts to emulate this applicability of coacervates through synthetic control of surfactant structures are finding success; however, there is little understanding of how to translate these changes into tailor-made properties. Herein, we designed 3-methyl-1-(octyloxycarbonylmethyl)imidazolium bromide (C8EMeImBr), an ester-functionalized ionic liquid-based surfactant, which shows better surface active properties than the nonfunctionalized and conventional cationic surfactant and forms complex coacervates over the broad range of concentration with sodium salicylate (NaSal). Mono- and divalent cations as well as ionic strength, viscosity, and time-dependent stability of the coacervates had also been addressed in order to study whether these coacervates could work as microreactors to encapsulate various molecules. The anionic charged complex coacervates with sponge morphology and honey comb-like interior show good efficiency to sequester cationic dyes from water because of electrostatic and hydrophobic interactions and good encapsulation efficiency for curcumin owing to their high surface area. Results suggest that ionic liquid-based coacervates studied here could be exploited as a novel low-cost, effective, and environmentally benign alternative to sequester dyes from the contaminated water and their recovery.