Extraction of lignin from corncob residue via a deep eutectic solvent for the preparation of nanoparticles by self-assembly

Abstract

• DES pretreatment is a valid method to extract lignin from corncob residue and reduce the heterogeneity of lignin for facilitating the formation of LNPs. • The content of lactic acid in DES has significant effect on the property of LNPs and the high content lactic acid facilitates the formation of LNPs. • Preparation of LNPs provides a possible direction for the reasonable and value-added utilization of the corncob residue. Reducing the structural heterogeneity of lignin and simultaneously improving the effective utilization of corncob residue is vitally important for biorefinery processing. In this study, lignin was extracted using a choline chloride/lactic acid-based deep eutectic solvent (DES) for the preparation of lignin nanoparticles (LNPs) by self-assembly. Nuclear magnetic resonance (NMR), fourier transform infra-red (FT-IR), scanning electron microscopy (SEM), and gel permeation chromatography (GPC) results showed that the extracted lignin exhib i ted different structural characteristics. In addition, the efficient pretreatment facilitated the isolation of lignin fractions from corncob residue, with yields and purities of up to 85.6% and 97.8%, respectively. Furthermore, the LNPs were characterized by a hydrodynamic diameter of 48.66 nm, polydispersity index below 0.2 and zeta potential values exceeding −42.2 mV. By investigating the impact of the DES pretreatment conditions on the corresponding LNP properties, the current study lays the groundwork for the further development and optimization of lignin recovery technology.