Phosphotungstic acid assisted with neutral deep eutectic solvent boost corn straw pretreatment for enzymatic saccharification and lignin extraction

[Display omitted] •Novel DES prepared by phosphotungstic acid and choline chloride/glycol.•94.4 % of enzymatic digestibility was acquired after pretreatment.•Hemicelluloses and lignin were effectively removed during the pretreatment.•The extracted lignin was in the form of lignin nanoparticles(LNP).•The system keeps excellent pretreatment performance after recycling process. In this study, the eco-friendly heteropoly acids-phosphotungstic acid (PTA) was chosen as a catalyst to assist neutral deep eutectic solvents (DESs) for deconstructing corn straw. The reactions were performed with a shorter time at 110–150 °C than other DES system. The results revealed that most of the lignin (86.1 %) and hemicellulose (89.7 %) were removed while cellulose was obtained in high yields (88.9–94.3 %). Benefiting from the removal of hemicellulose and lignin, the enzymatic digestibility of pretreated materials was noticeably boosted to 94.4 %, which was 5.3-fold higher than the untreated corn straw. Meanwhile, the regenerated lignin nanoparticle was acquired with a relatively high purity (more than 85 wt%), low and homogeneous molecular weight (5669−2437 g/mol). Furthermore, the PTA/DES demonstrated excellent cycle performance. Overall, technically feasible PTA catalyzed DES pretreatment presented in-depth analysis for effective deconstruction of corn straw recalcitrance for crops valorization in the future.