Microwave-Assisted Organosolv Delignification: A Potential Eco-Designed Process for Scalable Valorization of Agroindustrial Wastes

Abstract

The extraction of high-purity technical lignins at large scale, such as organosolv lignin, is still a challenge. The objective of this work was to verify the environmental feasibility of microwave-assisted organosolv delignification (MWAOD) of sugar cane bagasse (SCB) for scalable purposes. MWAOD studies were performed using 90% v/v CH3COOH combined with 2.0% v/v HCl (110 °C for 30 min). The effects of the MWAOD process on the lignin structure were evaluated. The results showed that increasing SCB mass in the microwave reactor causes considerable changes in neither the lignin yield and purity nor in their interunit linkages, monolignol composition, and thermal stability. Moreover, using recycled acetic acid spent liquor resulted in minor differences in the process parameters and lignin structure when compared to reactions with a fresh acid liquor. Therefore, MWAOD presents itself as a promising sustainable process for production of high-quality lignin in large scale with high yields.