Microporous Nitrogen-Doped Activated Biochars Derived from Corn: Use of Husk Waste and Urea for CO2 Capture

The increase in anthropogenic activity over time has led to an exponential increase in greenhouse gas emissions, especially CO2. Profitable technologies for CO2 capture and separation are conspicuous, and porous biochars derived from biomass waste can be a useful solution. Herein, we produced activated nitrogen-doped biochars for CO2 capture from corn husk waste, urea and K2CO3, named N-Bio-X (X = 600, 700, and 800 °C). N-Bio-X exhibited microporosity and different nitrogen contents and thus played an important role in the adsorption of CO2. N-Bio-700 exhibited the highest CO2 adsorption capacity, fastest adsorption kinetics and excellent stability after multiple adsorption-desorption cycles. N-Bio-600 showed excellent CO2/N2 selectivity, induced by nitrogen sites, particularly pyridinic and graphitic nitrogen. The cost-effectiveness of the raw material, coupled with its high adsorption capacity, rapid kinetics, and stable properties, provided highly promising N-doped biochars for practical implementation in CO2 capture and separations in postcombustion processes.