Recovery and reuse of ionic liquid cholinium glycinate in the treatment of brewery spent grain

Abstract

Recently, the ability of the biocompatible ionic liquid cholinium glycinate (N1112OHGly) for waste vegetable delignification like brewery spent grain (BSG) has been proved. However, the technical viability should march hand in hand with economic competitiveness. Therefore, the first step must address the reuse of the ionic liquid to mitigate the high cost associated with the synthesis of this kind of neoteric solvents. Different antisolvent-based strategies have been considered, in the present research work, to produce a delignified carbohydrate rich material (CRM) and reuse the ionic liquid. It was checked that the addition of a mixture of water: acetone (1:1 v/v) was able to efficiently precipitate carbohydrates with high levels of delignification, while about 97% of the ionic liquid is recovered at a purity near 72%. The use of this strategy allowed reusing N1112OHGly for 5 cycles and FTIR and XRD spectroscopy, scan electron microscopy (SEM) and, quantitative acid hydrolysis evidenced the suitability of the proposed process for the competitive sequential BSG delignification. Liquid chromatography sheds light on the recovery percentages and purity of the ionic liquid after each use.