Study of the carbonization temperature for a chemically activated carbon: influence on the textural and structural characteristics and surface functionalities

This study aims at investigating the relationship between the porosity and the surface functional groups of an activated carbon during the pyrolysis process. Several activated carbons are prepared by the carbonization of a mixture of olive waste and ZnCl₂ at different temperatures, which are chosen by taking into account the different phenomena occurring during this treatment. The porosity of the prepared carbons is investigated using both N₂ and CO₂ isotherms at 77 and 273 K, respectively. Long-range and short-range orders are studied respectively by X-ray diffraction (XRD) and Raman spectroscopy. The investigation of the carbon functionalities is carried out by Boehm titration, Fourier transformed infrared spectroscopy (FTIR) and water adsorption measurements. The effect of carbonisation temperature on the adsorption of cyclohexane provides additional information on the oxygen functional groups and especially the carboxylic proups. To summarize, the results show that a carbonisation at 573 K is sufficient to obtain a well-developed porosity and to ensure already the formation of acidic surface groups and especially the carboxylic groups.