(704f) Ionothermal Carbonization of Agricultural Waste into Porous Biochar for CO2 Capture

Carbon capture, utilization, and storage are emerging technologies to effectively mitigate CO₂ emissions and advance Net Zero technologies. Biochar is regarded as one of the promising CO₂ capture materials. Agricultural waste/residue, a carbon-rich material, can be converted into biochar via several thermochemical pathways. However, different CO₂ capture applications require different biochar properties and hence different synthesis methods¹. Ionic liquid (IL) solvents can be integrated into traditional thermochemical conversions of biomass to produce advanced porous carbonaceous materials². Biomass is mixed into an IL solvent, and the mixture is treated under medium pressures and temperatures, which is similar to wet/hydrothermal carbonization of biomass. The main product is known as ionochar. This process, which is called ionothermal carbonization (ITC), has not been well explored for agricultural residues.

ITC of agricultural waste was investigated at a fixed reaction temperature of 200 °C with IL solvents (e.g., ChCl, ChOH, and ChFeCl₄). The ionochar produced was further impregnated with varying metals, such as Ca, Mg, and Al, and subsequently treated under nitrogen gas from 500 to 900 °C to obtain activated ionochar for CO₂ capture. IL solvents, impregnated metals, and treated temperatures were observed to significantly affect the properties of activated ionochar in terms of, for example, specific surface area and CO₂ uptake ability. The specified activated ionochar with overall best properties was further tested for CO₂ capture ability with synthetic powerplant flue gas. Our findings indicated that activated ionochar from agricultural waste can have valorization of CO₂ capture with low capital cost and good adsorption capacity.

Reference

¹A. N. Shafawi, A. R. Mohamed, P. Lahijani, M. Mohammadi (2021) Journal of Environmental Chemical Engineering 9(6): 106869.

²L. Cibien, M. Parot, P.N. Fotsing, P. Gaveau, E. D. Woumfo, J. Vieillard, A. Napoli, N. Brun (2020) Green Chemistry 22: 5423-5436.