A comprehensive process of pretreatment and oxidation of lignin char was developed to optimize the production of activated carbon. The lignin char was obtained by carbonization of lignin under nitrogen at 600°C for 2 hours. The optimum time and temperature used to oxidize the char without destruction were, respectively, 6 hours and 245°C. The oxygen improves the reactivity of the sample in CO2 and evolved the sample of a thermoplastic behaviour to a thermosetting behaviour. The oxygenation in air of the lignin char does not change the mode of deformation acquired by the material during the carbonization. The preoxidized coal reacts more than the nonoxidized coal during the CO2 activation, whereas the reduction in volume in the first case is smaller than in the second. The preoxidized and then activated carbon shows the formation and the development of microporosity at the expense of macroporosity. This microstructure is one of the main characteristics of activated carbon, which can be used as adsorbent for different pollutants. 1. Introduction The activated carbon can be prepared from organic substances of various origins. The physical activation, which consists in carbonizing the organic matter and to gasify the char, is one of the methods to prepare the activated carbon. During their carbonization, the majority of the organic substances acquire, in the case of a plastic deformation, thermomechanical characteristics and physical properties that confer thermal resistance to coals during their gasification. Fossil coals are most stable thermically and their activation requires relatively high temperatures [1]. It would seem, according to the literature, that the reoxygenation of fossil coals makes it possible to reduce their thermal resistance and consequently to improve their reactivity [2–6]. Oxidation in air of the fossil coals is a fundamental stage in the preparation of the activated carbon. The operation consists in treating coal in air at temperatures lower than 400°C [7, 8]. The literature specifies that the pretreatment acts on the physical properties in particular on the thermoplasticity [9–14], on the chemical composition [15–20], and on the porous structure [21–26]. The reoxygenation is also applied to coals of vegetable origin [15, 20, 27–29]. Some work was interested in carrying out the pretreatment before or after carbonization. According to Fernandez Iba？ez [27], the reactivity of coal during the gasification is better when the preoxidation is carried out before carbonization of the olive cores and the apple pulp. On the other hand, our
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