Impact of pyrolysis heating methods on biochars with enhanced CO2/N2 separation and their incorporation in 3D-printed composites

N-doped biochars, derived from chitosan sourced from waste crustaceous shells, were produced via microwave- assisted pyrolysis at temperatures ranging from 400 to 800 degrees C to enhance CO2 2 and N2 2 separation. Their performance was compared with biochars from conventional pyrolysis. Microwave-derived biochars exhibited superior CO2 2 adsorption capacity at 25 degrees C and 100 kPa (0.78 - 1.56 mmol g- 1 ) compared to conventionally produced ones (0.55 - 1.43 mmol g-- 1 ). Increasing the pyrolysis temperature up to 600 degrees C significantly improved biochar properties, including surface area, pore volume, and CO2 2 adsorption capacity. Microwave-derived biochar featured enhanced surface area, larger pore volumes, and unique morphologies, requiring, on average, 61 % less preparation time. The higher ultramicroporosity and N-species concentration correlated with superior performance in the biochar produced at 600 degrees C. In gas mixture experiments (20 % CO2 2 and 80 % N2) 2 ) under flow conditions, these biochars showed rapid adsorption/desorption rates due to enhanced macroporosity at samples produced at 600 and 800 degrees C, facilitating gas diffusion along the ultramicropores. Adsorption heat analysis indicated that the CO2 2 adsorption is predominantly driven by physisorption, supported by complete sample regeneration when applying N2 2 flux or increasing the temperature during desorption. The study also explores the feasibility of 3D-printing a composite using the most effective biochar and inorganic polymers sourced from waste, presenting potential benefits for industrial applications.