β-Ga 2 O 3 photocatalyst powder suspended in perfluorooctanoic acid aqueous solution exhibited the degradation efficiency as high as 98.8% (Zhao et al. 2012).
Treatments of Organic Dyes
Photocatalytic degradation of dyes is the typical way to investigate the
photocatalytic activity of synthesized photocatalysts. Before utilizations of the
catalysts in other applications, the photocatalytic degradations of model dyes, e.g.,
methylene blue or methyl orange, are commonly done. Therefore, there are a large
number of publications reported on this issue.
Powder suspension of titanium dioxide (TiO 2 ), zinc oxide (ZnO), and others has
been extensively performed for photocatalytic removal of industrial organic pollutants in wastewater, especially dye-containing wastewater. Photocatalytic activity of
ZnO nanoparticles for the decomposition of rhodamine B dye under UV illumination
has been investigated. It was found that ZnO nanoparticles could degrade rhodamine
B dye to 95% within 70 min. Photocatalytic degradation of azo dye in aqueous
solutions under UV irradiation using nanostructured strontium titanate (Sr 2 TiO 3 )
showed high photocatalytic activity compared with that of TiO 2 (Karimi et al. 2014).
In addition, in photocatalytic degradation of dimethyl phthalate (DMP) (Jing et al.
2018) by TiO 2 particles, it was found that the photodegradation occurs at the surface
of the photocatalysts more than in the homogenous phase.
Graphene–oxide hydrogel (zeolitic imidazolate framework) shows photocatalytic
dye degradation ability with multiple cycles of uses because of its hydrophobic
properties and high specific surface area (Mao et al. 2017). Amorphous
photocatalysts of Zn-Al layered double hydroxide can be used for photocatalytic
decoloration of methyl orange (Qu et al. 2017). SrSn(OH) 6 can be used for the degradation of rhodamine B (Luo et al. 2016). At low pH, SrSn(OH) 6 shows a good
photocatalytic activity compared with commercial TiO 2 (P25), because the hexagonal phase of hydroxide stannate can create hydroxyl groups for degradation of
rhodamine B. Many modifications of metal oxides, e.g., Ag/TiO 2 nanoparticles
(Abdel Messih et al. 2017) and Nd 2 Sn 2 O 7 (Zinatloo-Ajabshir et al. 2019), have
been developed for degradation various organic dyes. Some details of the modifications will be discussed in another session.
Even though the suspension of photocatalysts in wastewater is the efficient form
for photocatalytic treatments of organic pollutants in water because of high surface
contacts between the surface of heterogeneous photocatalysts and organic pollutants
in water, the suspension form has major concerns about the recovery and reuse of the
suspended materials and also the leak possibility to the environment of the
photocatalysts. Therefore, the reuse strategies and leakage protections of the catalysts are ones of the challenges.
1 Photocatalytic Remediation of Organic Pollutants in Water
27
Treatments of Organic Dyes
Photocatalytic degradation of dyes is the typical way to investigate the
photocatalytic activity of synthesized photocatalysts. Before utilizations of the
catalysts in other applications, the photocatalytic degradations of model dyes, e.g.,
methylene blue or methyl orange, are commonly done. Therefore, there are a large
number of publications reported on this issue.
Powder suspension of titanium dioxide (TiO 2 ), zinc oxide (ZnO), and others has
been extensively performed for photocatalytic removal of industrial organic pollutants in wastewater, especially dye-containing wastewater. Photocatalytic activity of
ZnO nanoparticles for the decomposition of rhodamine B dye under UV illumination
has been investigated. It was found that ZnO nanoparticles could degrade rhodamine
B dye to 95% within 70 min. Photocatalytic degradation of azo dye in aqueous
solutions under UV irradiation using nanostructured strontium titanate (Sr 2 TiO 3 )
showed high photocatalytic activity compared with that of TiO 2 (Karimi et al. 2014).
In addition, in photocatalytic degradation of dimethyl phthalate (DMP) (Jing et al.
2018) by TiO 2 particles, it was found that the photodegradation occurs at the surface
of the photocatalysts more than in the homogenous phase.
Graphene–oxide hydrogel (zeolitic imidazolate framework) shows photocatalytic
dye degradation ability with multiple cycles of uses because of its hydrophobic
properties and high specific surface area (Mao et al. 2017). Amorphous
photocatalysts of Zn-Al layered double hydroxide can be used for photocatalytic
decoloration of methyl orange (Qu et al. 2017). SrSn(OH) 6 can be used for the degradation of rhodamine B (Luo et al. 2016). At low pH, SrSn(OH) 6 shows a good
photocatalytic activity compared with commercial TiO 2 (P25), because the hexagonal phase of hydroxide stannate can create hydroxyl groups for degradation of
rhodamine B. Many modifications of metal oxides, e.g., Ag/TiO 2 nanoparticles
(Abdel Messih et al. 2017) and Nd 2 Sn 2 O 7 (Zinatloo-Ajabshir et al. 2019), have
been developed for degradation various organic dyes. Some details of the modifications will be discussed in another session.
Even though the suspension of photocatalysts in wastewater is the efficient form
for photocatalytic treatments of organic pollutants in water because of high surface
contacts between the surface of heterogeneous photocatalysts and organic pollutants
in water, the suspension form has major concerns about the recovery and reuse of the
suspended materials and also the leak possibility to the environment of the
photocatalysts. Therefore, the reuse strategies and leakage protections of the catalysts are ones of the challenges.
1 Photocatalytic Remediation of Organic Pollutants in Water
27