Geoscience Reference
In-Depth Information
Figure 10.70 SEM photographs of selected HAp crystals.
Source: Photographs courtesy of W. Suchanek.
A higher experimental temperature of 180
C was effective for producing highly crys-
tallized anatase with rod-like crystals of 100
150 nm in length on HAp crystals.
In recent years, several new composites for enhancing photocatalytic properties
have been reported
[337,338]
.Wuetal.
[337]
have reported the synthesis of
HNbWO
6
/Mo nanocomposites for photocatalytic applications. This nanocomposite
was obtained in several steps involving the preparation of HNbWO
6
, LiNbWO
6
,
then [Fe
3
(CH
3
COO)
7
(OH)(H
2
O)
2
]NO
3
was added with Deggusa P-25 grade unsup-
ported TiO
2
.M
2
1
(M
Mn, Ni, and Cu) or M
3
1
(M
Cr and Fe) ions were incor-
porated into the interlayer of HNbWO
6
by hydrothermal reactions of HNbWO
6
with 1 M M(NO
3
)
2
or M(NO
3
)
3
aqueous solution in an autoclave at 120
C for
12 h. After being filtered and washed with water, the precipitate was heated at
250
C for 3 h so as to decompose any water remaining in the interlayer of
HNbWO
6
. The samples obtained thus were designated as HNbWO
6
/Cr
2
O
3
,
HNbWO
6
/MnO, HNbWO
6
/NiO, and HNbWO
6
/CuO.
Byrappa et al.
[338,339]
have prepared an activated carbon:titania (A.C:TiO
2
)
nanocomposite photocatalyst under hydrothermal conditions. Activated carbon has
long been recognized as one of the most versatile adsorbent materials used for the
effective removal of low concentrations of organic and inorganic species from solu-
tion and industrial wastewater.
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