Implementing efficient and sustainable pretreatment of Sorghum stalks for delignification and xylan separation with a...

Acidic deep eutectic solvent (DES) has garnered significant attention in biomass pretreatment due to its effectiveness. Octadecyl trimethyl ammonium chloride (OTAC) is a highly efficient surfactant, which is expected to create new DES with additional pretreatment functions. Accordingly, a new ternary deep eutectic solvent (TDES) was synthesized from OTAC, propionic acid (PA), and p-toluene sulfonic acid (p-TsOH) for pretreating sorghum stalk under the relatively mild condition to enhance enzymatic saccharification of sorghum stalks. Through the treatment with OTAC:PA:p-TsOH (1:2:0.1, mol:mol:mol) at 80 °C for 30 min, the enzymolysis efficiency of sorghum stalks was increased to 69.3 %. The accessibility of sorghum stalk to cellulose was increased to 414.3 mg dye/g cellulose while the surface area of lignin decreased to 517 m²/g. Along with the altered cellulose crystal structure and surface properties, the pretreatment mechanism for improving enzymatic hydrolysis capacity was proposed. Overall, this research implemented an efficient pretreatment using TDES OTAC:PA:p-TsOH for the valorization of sorghum stalk, providing a novel approach for the depolymerization and value-added utilization of lignocellulosic biomass in biorefining technology.