instability of the nanosized particles, the TiO 2 nanoparticles (NPs) may aggregate
during the photocatalytic degradation. This aggregation of TiO 2 nanocomposites
may obstruct the incident light on active centers, which consequently results in the
reduction of catalytic activity. Besides this, one of the main practical challenges is to
recover nanosized TiO 2 particles from the treated wastewater. To overcome these
limitations, the lattice of TiO 2 is doped with other metal ions (Sahoo et al. 2005).
Such doping results in an improved visible-light activity and improved removal
efficiency as demonstrated in Fig. 10.8.
In a recent study, for the removal of Acid Red 88, Behnajady et al. (2008) found
that silver-doped TiO 2 was more efficient than the undoped TiO 2 . The advantages of
the doped TiO 2 -based photocatalyst and the respective improvements in the mechanism have been summarized in Table 10.6.
Fig. 10.7 Disadvantages of
the TiO 2 /UV process
Fig. 10.8 Schematic representation of the advantages of modified TiO 2 NPs
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during the photocatalytic degradation. This aggregation of TiO 2 nanocomposites
may obstruct the incident light on active centers, which consequently results in the
reduction of catalytic activity. Besides this, one of the main practical challenges is to
recover nanosized TiO 2 particles from the treated wastewater. To overcome these
limitations, the lattice of TiO 2 is doped with other metal ions (Sahoo et al. 2005).
Such doping results in an improved visible-light activity and improved removal
efficiency as demonstrated in Fig. 10.8.
In a recent study, for the removal of Acid Red 88, Behnajady et al. (2008) found
that silver-doped TiO 2 was more efficient than the undoped TiO 2 . The advantages of
the doped TiO 2 -based photocatalyst and the respective improvements in the mechanism have been summarized in Table 10.6.
Fig. 10.7 Disadvantages of
the TiO 2 /UV process
Fig. 10.8 Schematic representation of the advantages of modified TiO 2 NPs
10 Photo-oxidation Technologies for Advanced Water Treatment
239