Later, the MB adsorption behavior at different initial solution pH
was carried out and shown in Fig. 4a. It is found that MB uptake of
graphite is improved after oxidation, which may be resultant from
two facts. On the one hand, the dispersibility of graphite has been
enhanced after introducing some functional groups by oxidation,
which has been already observed directly under TEM as mentioned
above. MB could have access to the inner interplanar sites of GO.
On the other hand, the binding modes of dye with adsorbents are
quite different between graphite and the GO series. Planar graphite
is facile to form parallel – stacking interactions with MB in water
[23–25], which occupies much effective space on graphite, resulting
in low dye uptake. As for the GO series, the initial ordered structures
are destroyed, and MB would be ready to vertically stand on the GO
plane via electrostatic interactions, which mode is obviously moreefficient and stronger. In addition, MB uptake of GO1 is also low,
which is ascribed to its low oxidation degree and following the
similar adsorption manner to graphite