Abstract
This is an overview of the photocatalyst TiO2
which gets activated under UV
rays. Its use in wastewater management is discussed. TiO2
is a semiconductor that uses
the transient nature of electrons and holes to produce radicals such as OH• and HO2• to
degrade organic pollutants, inorganic pollutants, and pathogens, particularly into
carbon dioxide, water, and oxides of organic compounds, respectively. The oxides are
recycled back into the biogeochemical cycle. TiO2
differs in its structure such as
anatase, brookite, and rutile, and hence its properties. Besides this, there are several
methods of its preparation that can be obtained through natural sources or synthetic
preparation. To enhance the outcome of wastewater treatment, TiO2
is doped or
modified with certain elements. These include nonmetal Dopants such as porous
minerals, carbon materials (fiber, graphene, activated carbon), polymer materials (PLC,
PE), nitrogen, etc., and metals such as precious metals (Ag, Pt), ions (Fe3+, Mo5+).
Composite modifications are also done. The formation of hetero junctions is one such
method that enhances the activity of TiO2
to increase the photo response in the visible
and infrared regions. Co-doping is also done such as N and Co-doped TiO2
. Certain
parameters which affect the efficiency of TiO2
.> are discussed briefly along with the
limitations it has. The degradation rates of some doped TiO2
acting on methylene blue
and Rhoda mine B are recorded and a case study on the degradation of butachlor using
Degussa-25 is discussed briefly. While degradation, a new byproduct, i.e., carboxylic
ions (such as acetate and formate) was also found but later on, after undergoing photoKolbe’s reaction, CO2
was formed along with regenerated TiO2
. Here, peroxide ions
played a major role in degradation as due to the presence of common salt, there was a
competition to occupy the active holes of TiO2
. Hence, OH• became non-selective.