Wednesday, September 23, 2020

Waste Water Treatment Using Titanium dioxide Nanomaterials

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.

 

References

1. Boxi S. S.; Paria S. RSC Adv. 2015, 5, 37657-37668.

2. 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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