Treatment of waste water is very essential today
because of water shortage throughout the world. There are many waste water
treatment technologies available such as membrane separation,
precipitation/coagulation, biological treatment, fanton oxidation and many
other technologies to arrest contamination present in the waste water. Removal
of some impurities such as non-biodegradable organic compounds, complex organic
materials, nitrogen and phosphorous rich compounds, pathogenic organisms (like
virus, bacteria), microplastics, radioactive substance, etc are difficult with
the existing technologies because of their respective limitations. Presence of
such kind of impurities may cause several health problems to human beings and
animals. So, it is very much essential to develop a strong method to remove all
the impurities from the waste water.
Recently, nanomaterials have
attracted a lot to overcome such problem because of its multifunctional
properties. Advanced oxidation process (AOT) in presence of Titanium di-oxide (TiO2)
has widely used because of the several benefits such as the process is simple,
low cost, non toxic, and stable. TiO2 is an n-type semiconductor
nanomaterials. The TiO2 is potentially preferred over the other
compounds due to its high photocatalytic activity, biological and chemical
inertness, resistance to photo corrosion and favourable band energy gap. Titanium
dioxide is generally exists in three crystalline phases, such as anatase,
rutile and brookite. However, the application of pure TiO2 as a
photocatalyst is limited in visible light because of its high band gap energy (3.03
eV for rutile and 3.18 eV for anatase). Modification of TiO2 in the presence
of other material in the form of either doping or impregnation drastically
improved the catalytic efficiency of TiO2.
The nanoTiO2 has high
specific surface area to volume ratio, which helps to arrest the ions on the
surface and also increase the efficient charge separation. TiO2, as
a photocatalyst, facilitates the removal of variety of pollutants either by
oxidation or by sunlight or artificial light as an energy sources. The TiO2
is not only used for the removal of impurities from the aqueous solution but
also it can remove some toxic vapours such as CO, hydrogen production
acetaldehyde, and NOX. It has also been noticed that TiO2
is useful for complete degradation of amenable organic compounds and
destruction of microorganisms such as virus and bacteria.
Regarding synthesis of TiO2
nanoparticles, several methods have been developed such as sol-gel process,
solvo-thermal process, chemical vapor deposition, electrochemical
method, hydrothermal process, etc. To improve the crystallinity of the synthesized
TiO2 calcinations are a generally done.
1.
Boxi S. S.; Paria S. RSC Adv. 2015, 5, 37657-37668.
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Behnajady, M.A.; Eskandarloo, H.; Modirshahla, N.; Shokri, M. Desalination 2011,
278, 10 –17.
3. Bekbolet M.; Araz C. chemosphere 1996, 32, 959-965.
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