الفهرس 
CHAPTER I. INTRODUCTIOOnly 14 pages are availabe for public view
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Abstract
Mesoporous nanotitania photocatalysts were
prepared by sol-gel method in acidic or basic media.
Three types of surfactants, namely, cetyltrimethyl
ammonium bromide (CTAB), sodium dodecyl benzene
sulfonates (DBS), and nonylphenol ethoxylate (NPE)
were used as templating agents. The effects of surfactant
type and pH on the morphology, particle size, surface
area, pore-size distribution, UV-Vis absorbance and TiO2
phase transformation were traced by SEM, TEM, BET,
and XRD. In absence of surfactants, XRD revealed 54.5%
anatase at pH 3-4 and 97.0% at pH 7–9. In presence of
surfactant, phase transformation of anatase has been
significantly inhibited such that anatase amounts to 82–
100% in acidic media. In basic media, the brookite phase
appeared in low concentrations (8–15%) while rutile
totally disappeared. The photocatalytic performance of the
synthesized catalysts was tested via naphthalene
degradation, which exhibited high activity in visible
irradiation (>400 nm). The data obtained indicate that the
surface area and pore volume of the current catalysts are
the most effective factors for photocatalytic performance.
Nevertheless, at the low pH (acidic) range, the CTAB
templated catalyst gave the highest surface area (86.7
m2/g), which is mainly assigned to acquiring the highest
photocatalytic degradation of naphthalene (97% after 3 h
irradiation time).
Moreover, the doping TiO2 with different contents of
non-metal multiwall carbon nanotubes (MWCNTs) in
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acidic medium has caused suppression of phase
transformation to the rutile phase using all concentrations
investigated. Raman spectral data confirmed the
occurrence of strong interaction between MWCNTs and
TiO2. The surface properties (surface area and the pore
volume) of MWCNTs/TiO2 composites are found to
increase as the carbon content increases. Furthermore, the
introduction of MWCNTs has caused an evident red shift
at frequencies above 390 nm. Among the CNT/TiO2
nanocomposites with different CNT contents, it is found
that the 0.03% CNTs containing TiO2 has acquired the
highest photo catalytic activity. For comparison of
combining the highly active 0.03% CNTs with the most
highly effective surfactant (CTAB), it is found that the
most significant photoactive synergy took place, i.e.,
complete photodegradation of NP pollutant after 60 min.
Two transition metals, Fe, Cu and Cu-Fe co-doping in
TiO2 in acidic medium were carried out. In case of
Cu/TiO2 composite, a decrease of the rutile phase to 36%
compared to pure TiO2 is obtained. However, there is an
increase of rutile in Fe/TiO2 catalyst to 49.5%. It is
interesting to note that Cu-Fe/TiO2 catalyst gives a
dramatic decrease of rutile phase (25.5%). The doping
metal ions have resulted in increasing the specific surface
areas due to modifying the morphology of TiO2 and
promoted the formation of mesoporous structures.
Furthermore, the enhancement of surface area of TiO2 (A)
by Fe is higher than that by Cu because the radius of Fe3+
is almost equal to that of Ti4+. Also, the pore volume
values are found to increase with doping any one of two
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metal oxides. As a result of the modification with the
transition metal oxides, the absorption of TiO2 extended in
visible region of solar spectrum. This is attributed to the
charge-transfer transition between the d electrons of the
transition metal and the TiO2 conduction or valence band.
The catalytic activities of the catalysts under investigation
could be arranged to be in the order:
Fe/Cu-A > Fe-A> Cu-A> A or P25.