Synthesis and characterization of activated carbon from Asphodelus microcarpus in two steps

The aim of the present work was to prepare an activated carbon from new precursor Asphodelus microcarpus using KOH as an impregnating agent, in two steps and in the absence of nitrogen. Its preparation requires a pre-carbonization at 500 °C for 60 min in order to obtain the char. Then activation of the char is realized by using KOH using as activating agent variable impregnation ratio: char/activating agent. Calcination is then carried out at 750 °C and 850 °C for 1 hour without azote. The determination of the optimum conditions is carried out by measuring the iodine number and that of methylene blue. The characterization of the chosen product is carried out by the following techniques: BET, FTIR-ATR, SEM and DRX. Under optimum conditions with mass ratio 1:4 at 750 °C (the calcination temperature), the specific surface area is equal to 1025.75 m2.g-1 and we obtain micro-meso activated carbon. The adsorption kinetics of dye chosen agrees with the pseudo-second-order model, and it appears that Freundlich (two parameters model) and Redlich-Peterson (three parameters model) describe better the adsorption data. Error analysis also showed that the Freunlich model better described the adsorption of Eriochrome Black T compared with the three parameter models. KEY WORDS: Asphodelus microcarpus, Two-stage activation process, Chemical activation, Adsorption, Dye   Bull. Chem. Soc. Ethiop. 2024, 38(1), 199-212. DOI: https://dx.doi.org/10.4314/bcse.v38i1.15