**3.6 Titanium dioxide (TiO2) based nanoparticles (NPs)**

Semiconducting, photolytic, energy-converting, electrical and gas sensing capabilities are found in TiO2. Rutile, anatase and brookite are three polymorphs of TiO2 crystals found in nature. These NPs are commonly available, affordable and non-toxic that's why these can be used to remove organic contaminants. The light energy is greater than band gap of semiconductor TiO2 is necessary for the removal of different organic pollutants [51].
