Drastic enhancement of CO₂ adsorption capacity by negatively charged sub-bituminous coal

Climate change is a key problem of the 21st century. Climate change is mainly caused by anthropogenic CO₂ emissions, and one solution to this problem is to capture and store CO₂ in deep coal seams, where it is immobilized by adsorption to the coal surface. Here we propose to modify the coal with methyl orange (MO), a typical dye that is also a major pollutant of the hydrosphere and removed thereby. Thus, raw and MO-modified coals were characterized to investigate their thermal stabilities, textural properties, carbon contents, surface characteristics, and CO₂ adsorption on the coal samples was measured at typical storage conditions (323 K and pressures up to 37.5 bar). CO₂ adsorption dramatically increased in the MO-coal, from 1.95 mol. kg⁻¹ (raw coal) to 18.7 mol. kg ⁻¹. This work thus aids in the development of improved methods for CO₂ storage, to significantly mitigate climate change.