STEAM ACTIVATION OF OLIVE STONE CHARS, DEVELOPMENT OF POROSITY

The porous texture of a char prepared by carbonization of olive stones has been modified by steam activation under different experimental conditions (steam flow, temperature, and residence time). All activated carbons thus prepared exhibit a pore volume that increases with burn-off, micro and macroporosity being the pore ranges predominating in all carbons. The steam flow used (100, 200, or 300 ml/min) does not much affect the development of micro or mesoporosity, but it affects the macroporosity (especially at low burn-offs), which increases with steam flow. In general terms, a low activation temperature (800 degrees C) favors the widening of narrow micropores (smaller than about 0.7 nm); when the activation temperature is increased to 850 degrees C, there is a general increase in porosity, decreasing for higher temperatures.