Rapid and efficient microwave-assisted guanidine hydrochloride deep eutectic solvent pretreatment for biological conversion of castor stalk

Microwave-assisted guanidine hydrochloride deep eutectic solvents (DESs) was developed for rapid and efficient pretreatment of castor stalk. The DES synthesized with guanidine hydrochloride and lactic acid showed a better delignification (92.02%) and enzymatic saccharification yield (96.3%) than choline chloride and lactic acid DES resulted. In addition, high-purity (up to 98%) lignin was recovered from the pretreatment liquor. The good recyclability of the guanidine hydrochloride-based DES was also proven with up to 90% cellulose hydrolysis with third-time recycled DES without post purification. The proposed microwave-assisted guanidine hydrochloride/ lactic acid DES showed its great potentials as a highly effective and recyclable pretreatment solvent for future biorefinery strategies.

Automated summary

A microwave-assisted guanidine hydrochloride deep eutectic solvent was developed for the pretreatment of castor stalk, showing high efficiency in delignification and enzymatic saccharification, as well as excellent lignin recovery. The guanidine hydrochloride-based DES demonstrated good recyclability and high cellulose hydrolysis rates, making it a promising pretreatment solvent for future biorefinery strategies.