Engineered biochar as a potential adsorbent for carbon dioxide capture

Increase of atmospheric CO2 concentration, a key driver of global warming and climate change, has become an increasing environmental and economic concern over the past decades. Biochar has been identified as a promising sorbent for capturing CO2, owing to its low-cost, eco-friendliness, high porosity, and easiness to modify surface structure. Various strategies are used to upgrade biochars’ surface chemistry to obtain high-quality CO2 sorbents. Modified biochars typically have higher surface areas and pore volumes, extensively developed pore structures, and more O- and N-containing functional groups than pristine biochars. Therefore engineered biochars exhibit excellent CO2 uptakes via enhanced physisorption and inner- and outer surface complexations. Moreover, their high regeneration capacity reduces the total CO2 removal costs. This chapter discusses different strategies for producing engineered biochars, factors affecting CO2 adsorption capacity of pristine biochar, and challenges and future perspectives of using engineered biochar as an adsorbent for CO2 capture.