Civil Engineering Reference
In-Depth Information
O
2
e
-
O
2
+-
e
-
-
-
(1)
UVA
(2)
TiO
2
Visible (400 nm)
OH
+
+
+
h
+
h
+
H
+
H
2
O
16.3
Change in band gap and generation of free radicals in TiO
2
photocatalyst.
combination of photochemical and electrochemical system was used for
the degradation of organic pollutant such as Rhodamine 6G (R-6G) (Chen
et al.
, 2003). Fine TiO
2
particles have shown better effi ciency than the immo-
bilized catalysts, but complete separation and recycling of fi ne particles (less
than 0.5
m) from the treated water, are very expensive. Therefore, from
an economical point of view, this method is not suitable for the industrial
scale. This problem was solved by fi xing the carbonblack-modifi ed nano-
TiO
2
(CB-TiO
2
) on aluminium sheet as a support (L. Li
et al.
, 2003). The
photocatalytic activity of CB-TiO
2
thin fi lms was observed to be 1.5 times
greater than that of TiO
2
thin fi lms in the degradation of reactive Brilliant
Red X-3B.
Decomposition of parathion with the nanometer rutile titanium dioxide
(TiO
2
) powder as the sonocatalyst after treatment of high-temperature
activation was carried out by Wang
et al.
, (2006). In the study by Li
et al.
(2006a), carbon grain coated with activated nano-TiO
2
(20-40 nm) (TiO
2
/
AC) was prepared and used for the photodegradation of methyl orange
(MO) dyestuff in aqueous solution under UV irradiation. Mahmoodi
et al.
(2007) immobilized TiO
2
nanoparticles for the degradation and mineraliza-
tion of two agricultural pollutants (Diazinon and Imidacloprid as
N
-hetero-
cyclic aromatics).
The photocatalytic effi ciency of immobilized TiO
2
nanoparticle with 6 nm
diameter (supported by glass substrate) as well as conventional suspended
catalysts has been investigated recently by Mascolo
et al.
(2007) for the
degradation of methyl red dye. Although the mechanism for dye degrada-
tion was found to be the same for both cases (suspended as well as
μ
Search WWH ::
Custom Search