indicates the SEM display for the morphology and
distribution of kaolin, nZVI, and K-nZVI. Fig. 3(a) shows that kaolin
is a kind of schistose, sheet mineral, and there are plentiful small,
irregular and acicular crystals among the interlaminations. The
morphology of synthesized nZVI generally exists as chain-like
aggregates and most of them were spherical as shown in Fig. 3(b)
[12]. The diameter of nZVI nanoparticles largely ranged from 30 to
90 nm. There were many black granules among the schistose, sheet
interlaminations, which were synthesized nZVI nanoparticles in
Fig. 3(c). It indicated that aggregation had decreased and more
singular spherical nanoparticles appeared after being supported
onto the calcinated kaolin. This resulted in a less chain-like
existence and better distribution in the kaolin (Fig. 3(c)) compared
to nZVI alone (Fig. 3(b)). Similar results were observed in the nZVI
that supported kaolin in removing heavy metals [7,8]. The
dimensions of K-nZVI had clearly increased and the surface
became scabrous after reaction due to the formation of iron oxide
layers such as Fe3O4, Fe2O3, Fe (OH)3 and FeOOH (see Fig. 3(d)).
Consequently the black granules gradually declined in number
while the gray particles increased in number for nZVI covering on
calcinated kaolin surface