A study on the impact of the reaction mechanism of the thermochemical activation of bone char (by pyrolysis and carbonization)

Porous materials based on bioapatite were prepared through the thermochemical activation of pork bone char, using different reagents (H2SO4 and K2CO3), heating atmosphere (inert and oxidizing) and activation temperature. Thermogravimetric analysis coupled to mass spectrometry was used to propose a detailed activation mechanism. Regarding the effect of each reagent on the activation, whereas that of H2SO4 is attributed to specific reactions, the effect of K2CO3 is ascribed to (i) the role of K+ as a catalyst for reactions such as the gasification of carbon and (ii) the incorporation of carbonates, involved in several reactions. The best textural properties are obtained in an oxidizing atmosphere at 350 ºC. The beneficial effect of the combustion reactions at an intermediate temperature results in a cost-effective preparation protocol. H2SO4 leads to a selective development of microporosity. The oxidizing atmosphere is involved in the generation of OH- functional groups. These results demonstrate the feasibility of configuring activation protocols to tailor the physicochemical properties of biapatite-based materials, for use in specific fields.