A novel deep eutectic solvent–mediated Fenton-like system for pretreatment of water hyacinth and biobutanol production

To facilitate depolymerization of cellulose into fermentable sugars, a novel deep eutectic solvent (DES)–mediated Fenton-like system was developed for efficient removal of hemicellulose and lignin components from lignocellulosic biomass. Water hyacinth (WH) was treated with the newly synthesized DES (choline chloride-ethylene glycol-FeCl3; ChCl-EG-FeCl3) at 140 °C for 2 h and then subjected to treatment with 32 mL 30 wt% H2O2(Fe3+: H2O2= 1:50 mol·mol–1) for 1 h in a Fenton-like reaction system (DES/H2O2). Hydrolysate containing 28 g·L–1glucose was obtained, which was 19.6- and 1.6-fold of raw WH and WH pretreated by DES, respectively. The DES/H2O2-WH hydrolysate was further evaluated for butanol fermentation; no significant inhibition was observed on butanol production, giving butanol titer of 8.3 g·L–1, along with a yield of 0.18 g·g–1glucose and a productivity of 0.12 g·L–1·h–1. Remarkably, DES could be recovered and recycled for five consecutive batches.