Textural and functional modifications of activated carbons subjected to severe storing conditions

Different techniques to prepare activated carbons exist. Most of them lead to materials with interesting properties, however, as far as we know, these features have been barely evaluated over time. In this context, the evolution of the textural and surface chemistry properties over time of different activated carbons is evaluated. For this purpose, six commercial and a homemade synthetized activated carbons with different characteristics were put in a climatic chamber for 22 months under constant conditions of temperature and relative humidity (T = 40 °C, RH = 80%). The samples were characterized at different periods of time by means of N₂, CO₂ and H₂O adsorption measurements and by thermogravimetric analysis. The results show that contrary to what can be expected, the surface chemistry was not the only property that has undergone modifications but also the porous properties, and for some samples the latter was even very important. These changes were observed for all samples; however some of them are more affected like metal impregnated carbon and activated carbon fibers, whereas others seem to be more resistant to ageing such as chemically activated carbons.