Valorization of Moroccan Alfa Grass through Pyrolytic Conversion to Biochar for Atmospheric CO ₂ Capture

This work investigates the valorization of Alfa grass collected from eastern Morocco into biochar for CO₂ capture applications. Biochar was produced using tubular (under N₂) and muffle (in air) furnaces at 300, 400, and 500 °C. Comprehensive characterization (FTIR, Raman, SEM, TGA, BET, elemental analysis, and density) revealed strong correlations between the preparation conditions and structural/chemical properties. Experimental adsorption tests at 30 °C and 1 bar demonstrated that slow pyrolysis under N₂ produced superior materials, with a CO₂ uptake reaching ∼ 1.2 mmol g^-1 that was about 34% higher than that of air-treated counterparts. Although surface areas were relatively low, the presence of both micro- and mesopores combined with favorable surface chemistry played a dominant role in adsorption performance. Kinetic analysis further confirmed that selected samples (P500 and G300) could be fitted with a pseudo-second-order model (<i>R</i> ² ≈ 0.99), highlighting fast and effective adsorption.