Acid-enhanced ternary DES pretreatment of wheat straw guided by Kamlet–Taft parameters: boosting lignin separation and enzymatic hydrolysis

Abstract

In this study, ternary deep eutectic solvent (DES) systems were constructed by introducing solid acids (AlCl₃, PTA, FeBr₃) into binary DES systems to achieve improved lignocellulose separation efficiency and enhanced enzymatic hydrolysis. Correlation analysis between the Kamlet–Taft solvatochromic parameters and lignin extraction rate/enzymatic hydrolysis efficiency revealed that the pretreatment and enzymatic hydrolysis steps were significantly improved by enhancing the hydrogen bond acidity. Accordingly, ternary DES systems with better pretreatment efficacy were screened. Notably, using the ChCl/BDO/AlCl₃ (25 : 50 : 1) system at 120 °C for 60 min provided the most optimal pretreatment and enzymatic hydrolysis performance for wheat straw. After pretreatment under these conditions, an 85.74% lignin extraction rate was achieved, and 72 h of enzymatic hydrolysis provided a 99.67% polysaccharide degradation rate and 74.59% reducing sugar yield. This DES system maintained good pretreatment performance even after four reuse cycles. Moreover, this pretreatment strategy demonstrated good applicability to multiple biomass types, providing a novel approach for developing efficient and environmentally friendly lignocellulose separation technologies.