Microwave-assisted pyrolysis of biomass waste for production of high-quality biochar: Corn stover and hemp stem case studies

Abstract

The efficient conversion of biomass waste into valuable products is a critical challenge in sustainable energy and environmental management. Microwave pyrolysis of hemp stem and corn stover was studied for producing biochar suitable for CO2 adsorption, catalysts, water treatment, and soil enhancement. The effects of microwave power and absorbent agents on maximum temperature, yields, and biochar properties were investigated. Elevated power (33–120 W/g) reduced yield (42–16 wt%, 38 to 16 wt%) but increased carbon content (67–78 wt%, 65 to 75 wt%), BET surface area (1.05–69.37 m2/g, 0.59–43.18 m2/g) for hemp stem and corn stover respectively. Microwave absorbents like graphite, activated carbon, and water improved heating and biochar quality. Activated carbon notably increased carbon content (76–82 % wt, 71–80 % wt) and surface area (6.59–91.99 m2/g, 9.99–50.51 m2/g) for hemp stem and corn stover respectively. CO2 adsorption highlighted biochar microstructure with pore sizes averaging around 1 nm for both biomass. These findings demonstrate the potential of microwave-assisted pyrolysis and the use of absorbent agents to produce high-quality biochar for various applications.