Work

A chemical-recovery-free ammonium sulfite-based alkali pretreatment of corn stover for low-cost sugar production via fertilizer use of waste liquor

Year: 2025

Type: article

Abstract: • (NH 4 ) 2 SO 3 showed limited biomass delignification and deacetylation at 80 °C. • Alkali-facilitated sulfonation of biomass with AS occurs at low temperature. • A combination of KOH and (NH 4 ) 2 SO 3 achieved more than 95% total sugar yield. • The spent liquor from the pretreatment showed significant potential as a fertilizer. • The techno-economic analysis estimated a minimum sugar selling price of $0.285/lb. The production of cellulosic sugars is a pivotal strategy for advancing biomass bioconversion. This study evaluated the pretreatment of corn stover using ammonium sulfite and potassium hydroxide to develop comprehensive data on sugar, lignin, chemicals, and overall mass recovery profiles in a batch reactor at 80 °C. The results indicated significant improvements in delignification, deacetylation, enzymatic digestibility, and overall sugar yield. Specifically, pretreating corn stover with a solution of 40 wt% potassium hydroxide and 15 wt% ammonium sulfite at 80 °C for 2 h achieved 78.9 % lignin removal and 82.1 % acetyl removal, resulting in a total sugar yield exceeding 87.5 % with an enzyme loading of 12.5 mg protein/g-glucan plus xylan. The pretreated spent liquor, containing ammonium, potassium, sulfur, biomass-derived organics, and inorganics, demonstrated substantial potential as a fertilizer. The techno-economic analysis projected a minimum sugar selling price of $0.285 per pound, supporting the ongoing development and implementation of chemical-recovery-free pretreatment technology.

Source: Bioresource Technology

DOI: 10.1016/j.biortech.2025.132402