Non-aqueous solvent for efficient dissolution of polygalacturonic acid.

The ionic liquid 1-n-butyl-3-methylimidazolium chloride (BMIMCl) was found to be a non-aqueous solvent for the fast and efficient dissolution of polygalacturonic acid. Up to 5.3 wt% biopolymer could be dissolved by heating the mixture of biopolymer/BMIMCl to 140 °C. About 50% of the polygalacturonic acid groups form the corresponding imidazolium salt at elevated temperature with the solvent, this leads to the solubility of the biopolymer in the surplus of BMIMCl. The salt formation was investigated with nuclear magnetic resonance (NMR)- and Fourier transform infrared (FTIR) spectroscopy as well as by X-ray diffraction (XRD) and is considered to be the driving force for the dissolution of the biopolymer.