Sustainable biochar synthesis via synergistic H2O2-KOH modification for enhanced CO2 physisorption

Abstract

Excessive CO2 emissions lead to a gradual increase in global average temperatures and an increased frequency of extreme weather events. Exploiting advanced materials for CO2 capture has become a key issue of concern to all countries. In this study, a new biomass carbonization strategy, co-modification by H2O2 and KOH, is proposed to prepare microporous biochar from pine sawdust with high CO2 adsorption capacity. Results indicate that the co-modification strategy can produce biochar with a specific surface area as high as 3522.7 m2/g (with a micropore ratio of 90.3 %), which increases by 56.7 % compared to the biochar produced by biomass carbonization without H2O2 treatment. The adsorption properties of the co-modification-derived biochar are investigated by CO2-TPD and TG, and the biochar exhibits a maximum CO2 adsorption capacity of 6.60 mmol/g at 30 °C and retains over 91.2 % of this capacity after 10 cycles. It is revealed that H2O2-KOH modification can significantly promote the physisorption capacity of the biochar, highlighting the enhanced CO2 capture efficiency due to alkaline hydrogen peroxide treatment on the biochar and its enhancement in CO2 capture.

Keywords

• Biomass carbonization
• H2O2-koh co-modification
• Co2 adsorption
• Specific surface area