102
I. Ivanenko et al.
7.2 Classification of Photocatalysts
Photocatalysts for industrial application must have photo- and chemical stability,
biological inertness, high photosensitivity, developed specific chemically active
surface, ability to adsorp reagents under light quanta, and also to have available
resource base and low price [5]. As is evident, the main property of a photocatalyst
is its photocatalytic activity, which is determined by a combination of factors: type
of material that forms a photocatalyst; type of crystal structure of particles; form of
particles; porosity; concentration of surface hydroxide groups, etc. [6].
Photocatalytic structures can be classified taking into account the above features.
From the technological point of view, the most appropriate is the classification by
the type of solid-state material that forms the photocatalyst. This classification is
presented in Table 7.1.
As apparent from the data (Table 7.1), the majority of materials used as photocatalysts are related to transitional d-elements. In its atoms the orbitals of pre-outer
layer filled: cadmium, zinc, titanium, copper, iron, zirconium, wolfram, platinum,
palladium, gold, silver, cobalt, vanadium, niobium, chromium, tantalum, nickel. Pelements also widely used as composite materials for producing photocatalysts;
them valence electrons and orbitals of it are outer layers of the atom: selenium,
indium, bismuth, bromine, tin, lead, and also carbon, nitrogen, chlorine, sulfur and
oxygen. S-elements (strontium, potassium) and f-elements (cerium, samarium) are
used the least frequently for producing photocatalysts. The solid-state photocatalysts
with different crystal structure of particles can be used in the form of powders and
films [6].
Powder photocatalysts are used commercially as suspensions in water and other
solvents. Methods of obtain powder catalysts are relatively simple and consist of
two stages: direct synthesis of powder and its continued layout.
Film photocatalysts have significant advantages compared with powder in terms
of organization of technological process, especially at photocatalytic oxidation of
volatile toxic compounds. However, such photo catalysts are not used in industrial
conditions due to insufficient knowledge about them.
The substrate material plays a special role in its production, because it can affect
the photocatalytic activity. Optic fiber, glass, quartz, different metals, oxides, etc.,
are used as substrates [4].
7.2.1 Branches of Photocatalysts Applications
Among the publications devoted to photocatalysis, it is possible to single out
a number of articles of practical importance for the specialized application of
synthesized photocatalytic structures [6, 7]. The main areas of application of
photocatalysts in industry are: ecological purification of and industrial wastewaters
I. Ivanenko et al.
7.2 Classification of Photocatalysts
Photocatalysts for industrial application must have photo- and chemical stability,
biological inertness, high photosensitivity, developed specific chemically active
surface, ability to adsorp reagents under light quanta, and also to have available
resource base and low price [5]. As is evident, the main property of a photocatalyst
is its photocatalytic activity, which is determined by a combination of factors: type
of material that forms a photocatalyst; type of crystal structure of particles; form of
particles; porosity; concentration of surface hydroxide groups, etc. [6].
Photocatalytic structures can be classified taking into account the above features.
From the technological point of view, the most appropriate is the classification by
the type of solid-state material that forms the photocatalyst. This classification is
presented in Table 7.1.
As apparent from the data (Table 7.1), the majority of materials used as photocatalysts are related to transitional d-elements. In its atoms the orbitals of pre-outer
layer filled: cadmium, zinc, titanium, copper, iron, zirconium, wolfram, platinum,
palladium, gold, silver, cobalt, vanadium, niobium, chromium, tantalum, nickel. Pelements also widely used as composite materials for producing photocatalysts;
them valence electrons and orbitals of it are outer layers of the atom: selenium,
indium, bismuth, bromine, tin, lead, and also carbon, nitrogen, chlorine, sulfur and
oxygen. S-elements (strontium, potassium) and f-elements (cerium, samarium) are
used the least frequently for producing photocatalysts. The solid-state photocatalysts
with different crystal structure of particles can be used in the form of powders and
films [6].
Powder photocatalysts are used commercially as suspensions in water and other
solvents. Methods of obtain powder catalysts are relatively simple and consist of
two stages: direct synthesis of powder and its continued layout.
Film photocatalysts have significant advantages compared with powder in terms
of organization of technological process, especially at photocatalytic oxidation of
volatile toxic compounds. However, such photo catalysts are not used in industrial
conditions due to insufficient knowledge about them.
The substrate material plays a special role in its production, because it can affect
the photocatalytic activity. Optic fiber, glass, quartz, different metals, oxides, etc.,
are used as substrates [4].
7.2.1 Branches of Photocatalysts Applications
Among the publications devoted to photocatalysis, it is possible to single out
a number of articles of practical importance for the specialized application of
synthesized photocatalytic structures [6, 7]. The main areas of application of
photocatalysts in industry are: ecological purification of and industrial wastewaters