Agriculture Reference
In-Depth Information
I
NTRODUCTION
Nano titanium dioxide (nano-TiO
2
）
is a more excellent and applicable
photocatalytic material among many candidates for photocatalysts. There are
two types of photochemical reaction proceeding on a TiO
2
surface when
irradiated with ultraviolet light. One is the photo-induced redox reactions of
adsorbed substances, and the other is the photo-induced hydrophilic
conversion of TiO
2
itself. The former type has been known since the early part
of the 20
th
century, but the latter was found only at the end of the century. The
combination of these two functions has opened up various novel applications
of TiO
2
, particularly in the field of sustainable agriculture and building
industry. For sustainable agriculture, photocatalytic reaction of nano-TiO
2
is
potentially useful. In fact, nano-TiO
2
materials have a lot of advantages of high
photocatalytic activity, non-pollution, environmental friendly and no-harm to
human health, which facilitate the attempts of nano-TiO
2
materials' application
in sustainable agricultural production and environment protection. In nature,
TiO
2
presents as three cystal forms, i.e. anatase, rutile and brookite. Among
them, TiO
2
of anatase and rutile are more extensively studied and applied.
Nano-TiO
2
has become the most valuable and extensive application
semiconductor in sustainable agriculture based on its photocatalytic function.
Many chemicals, such as fertilizer, pesticides and fungicides, were input
in modern agriculture to increase yield and kill pathogens, which will lead to
environmental pollution directly or secondary pollution by their transforms.
The pollutants will spread or accumulate in soils, surface water and produce,
which poses serious a threat to environmental quality and human health. In
addition, organic wastes brought up during agricultural production usually
cause environment pollution or inhibitory effect on crop growth. To select
some methods to remove or decompose them without secondary pollution is
the best way to reclamation the environmental media. Here we take protected
crop production for example. Crop production under cover is the most
important pattern of modern agriculture with heavy chemical input. In
addition, some phytotoxic substances from straw or cultivated crops will
depress growth and yield of crops when they are cultivated successively in
protected systems for soilless vegetable production. Moreover, pathogens also
should be killed through more environmentally friendly methods other than
merely spraying pesticides. Nowadays, based on the current research
literatures, nano-TiO
2
has been used in remediation of polluted soil and water,
pathogens prevention and cure, and decomposition of phytotoxic substances in
