3.2. As (V) adsorption performance of prepared samples
Fig. 5 shows As (V)-removal performance of the prepared
samples. Both GO-N2 HT and Al-GO-N2 HT reveal poor removal
efficiencies, with Al-GO-N2 slightly better between the two. This
can be due to the removal of most of functional groups on the
surface of GO during N2 heat treatment that are responsible for As
(V) adsorption. It may be argued that adsorption of As (V) can be
facilitated by the hydroxyl groups on the alumina surface; however,
unfavorable thermal conditions during N2 pyrolysis disfavor the
formation of any surface hydroxyl group, and the presence of a
graphene layer blocks the alumina surface, resulting in a poor
removal efficiency of Al-GO-N2 HT.