Urea-pretreated corn stover: Physicochemical characteristics, delignification kinetics, and methane production

Area of Science:

• Biomass Conversion
• Anaerobic Digestion
• Biochemical Engineering

Background:

• Solids loading significantly impacts urea-based ammonia production and biomass pretreatment.
• Corn stover is a promising lignocellulosic feedstock for biofuel production.
• Efficient delignification is key to maximizing methane yields.

Purpose of the Study:

• To investigate the effect of solids loading and urea-to-corn stover ratios on methane production and delignification.
• To determine optimal conditions for maximizing lignin removal while preserving cellulose and hemicellulose.
• To analyze the delignification kinetics of urea-pretreated corn stover.

Main Methods:

• Incubation of urea-pretreated corn stover at various solids loading (10%-70%) and urea ratios (1:100-7:10) for 6 weeks at 35°C.
• Measurement of physicochemical characteristics, delignification rates, and methane production (L/kg VS).
• Kinetic analysis of the delignification process.

Main Results:

• Optimal urea:corn stover ratios of 1:20 (≤50% solids loading) and 7:10 (70% solids loading) were identified for high lignin removal.
• High retention of cellulose (82-85%) and hemicellulose (85-86%) was observed under optimal conditions.
• Maximum lignin removal rates of ~70% and methane production of ~294 L/kg VS were achieved.
• Delignification followed three first-order reaction kinetics, with most lignin degrading within 3 weeks.

Conclusions:

• Solids loading and urea ratio are critical parameters for optimizing urea pretreatment of corn stover for methane production.
• The identified optimal conditions balance efficient delignification with significant carbohydrate preservation.
• The study provides insights into the kinetics of delignification, aiding in process optimization for biofuel generation.