For both C-600 and C-1000 samples, the absorption capacities
for all organic liquids are almost in the same order
(Fig. 9a): ethanol 6 coal oil < diesel oil < paraffin oil < vegetable
oil 6 peanut oil < castor oil, which corresponds to the
increasing density of organic liquids. To further confirm these
trends, we investigated the relationship between densities of
various organic liquids and absorption capacity of C-1000
sample. It can be found that organic liquid with higher density
has a larger q value (Fig. 9b). It has been reported that
the absorption capacity is dependent on the void volume of
the porous materials [26]. Therefore, when the void volume
of materials is fixed, the organic liquid absorbed on the void
is also fixed, thereby leading to the obvious linear correlation
between the absorption capacity and the density of organic
liquid.