Extraction of 5-(Hydroxymethyl)furfural using Molecular Imprinting Polymers Based on Ionic Liquids Derived from Organic Acids

Molecularly imprinted polymers (MIPs) are promising not only for analytical applications but also for large-scale selective extraction processes. The purpose of this research was to develop MIPs based on ionic liquids with a more biocompatible approach for the extraction of 5-(hydroxymethyl)furfural (5-HMF) in solution, which is a toxin present in some heat-treated foods. For this purpose, IL monomers consisting of choline acrylate or methacrylated quaternary ammonium salts based on MAEDMA and carboxylates found in foods, such as vitamin C, were synthesized. Their structure was confirmed by proton nuclear magnetic resonance (1H NMR) and attenuated total reflectance-Fourier transform infrared spectroscopy (UATR/FTIR). These monomers were used to design systems with molecular footprints by forming host (target molecule)–guest (polymerizable monomers) complexes. To compare the performance of MIPs, a nonimprinted polymer (NIP) was prepared using the same methodology without a template molecule. The morphology and structure of the polymers were characterized by scanning electron microscopy and UATR/FTIR, respectively, and their adsorption capacity was analyzed by static adsorption studies and modeled by isotherms. Finally, compared with the NIP, the MIPs exhibited a significantly higher adsorption capacity. Selective adsorption of 5-HMF was higher in the MIP based on the functional monomer derived from vitamin C, which showed an impression factor of 1.72. Although MIPs based on monomers derived from citric, lactic, and acetic acids exhibited imprinting factor greater than 1, the MIP based on choline acrylate showed the highest 5-HMF adsorption capacity, with values of 35.94 mg·g–1, and its adsorption behavior was best described by the Langmuir–Freundlich model.