Page 123 - Materials Chemistry, Second Edition

104 Life Cycle Assessment of Wastewater Treatment

TABLE 6.2
Application of Photochemical Advanced Oxidation Processes for Dye
Decolorization
Heterogeneous Photocatalysis
Catalysts Dye Concentration Main Findings References
ZnO Congo Red, Methyl 30 mg L −1 Satisfactory Chen et al. (2017b)
Orange, and photocatalytic
Reactive Black 38 properties under
UV irradiation
Reactive Black 5 and 30–150 mg L −1 High decolorization Saggioro et al.
TiO 2
Reactive Red 239 rates after five (2011)
cycles of TiO 2
Y 2 O 3 Xylenol Orange and 20 mg L −1 High potential of Guo et al. (2017)
composites Rhodamine B TiO 2 /Y 2 O 3 and
Bi 2 O 3 /Y 2 O 3
composites for dye
removal
Toludine Blue, 20–80 µM Superior Rauf et al. (2007)
V 2 O 5 /TiO 2
Safranin Orange, performance of the
and Crystal Violet hybrid catalyst
Disperse Blue 79 4.5 mg L −1 Metallic gold Wang (2007)
Au/Fe 2 O 3
particles enhance
the photocatalytic
activity of the iron
oxide support

Heterogeneous catalysis by a wide range of nanocatalysts has been investigated
for the treatment of diverse contaminants, obtaining high degradation percentages in
most of the cases. In particular, TiO and zinc oxide ZnO are preferred, because they
2
are relatively inexpensive, non-toxic, and stable, and they present high oxidization
potential (Gmurek et al., 2017; Gaya and Abdullah, 2008; Sousa-Castillo et al., 2016).
In particular, TiO has been applied in the photocatalytic treatment of polluted
2
wastewaters (Oros-Ruiz et al., 2013; Khodja et al., 2001; Barka et al., 2013; Khataee
and Kasiri, 2010).
In this section, we assess a heterogeneous photocatalytic system using
TiO nanoparticles for the treatment of matrices polluted with dyes, specifi-
2
cally Methyl Green, Orange II, and Reactive Blue 19, with remarkable chemi-
cal and structural differences. A number of factors that govern the kinetics
of photocatalysis, such as the catalyst concentration and pH, the addition of
oxidant, and the initial substrate concentration, were evaluated. The selected