Activation of grape seed char upon successive cycles of liquid phase oxidation followed by high temperature
desorption permits a tailored development of porosity. In this work three different oxidants (HNO3, H2O2, and
(NH4)2S2O8), have been tested and the desorption temperature has been varied within 850–950 °C upon 10
activation cycles. A high increase of BET surface area was observed in the first five cycles with HNO3 as oxidizing
agent giving rise to values higher than 1200 m2 g−1 at around 50% burn-off. Activation with H2O2 and
(NH4)2S2O8 led to a significantly lower development of surface area, with 600 and 800 m2 g−1 respectively at
that burn-off. The analysis of the pore size distribution showed that porositywas generated through the creation
of new micropores and widening of existing ones upon activation with HNO3 and (NH4)2S2O8, whereas H2O2
mostly led to the widening of the narrowmicropores already existing in the starting char. The activated carbons
obtained are essentially microporous, with some small contribution of mesoporosity in the HNO3 series
(Vmicro = 0.69 cm3 g−1; Vmeso = 0.07 cm3 g−1). SEM images showed that the activated carbons maintained
the granular morphology of the seeds after 10 cycles showing a hollow core structure with a wall thickness of
about 200 μm.