Aromatic nitration has long been an important process in industrial chemistry, because nitroaromatic products are widely used as dyes, pesticides, solvents, drugs, and intermediates for the manufacture of synthetic dyes and other chemicals. Traditionally nitration is carried out by using mixture of concentrated nitric acid (98%) and sulphuric acid in the proportion of 1:2. However the process produces large quantity of dilute sulphuric acid which leads to environmental pollution.

Diethyl phthalate (DEP) is an odorless, colorless, oily liquid. It is used to make plastics, pesticides, cosmetics, and aspirin, as well as toothbrushes, auto parts, toys, tools and food packaging. At the same time, DEP has a negative impact on human health and causes environmental problems.

Nearly 20% of water pollution is caused by the leather and textile industries. Textile wastewater contains a lot of organic pollutants, including dyes that are widely used in industry. At the same time, printing and dyeing wastewater has also caused water problems and health problems.

In the past decade, the application of semiconductor powder as a photocatalytic degradation of organic pollutants in water has received widespread attention. Titanium dioxide (TiO2) suppresses amazing photocatalytic properties, including high activity, chemical stability, and low cost. However, the photocatalytic activity of TiO2 (with a band gap of 3.2 eV, excited by photons with a wavelength of less than 387 nm) is still limited by UV wavelength irradiation, so the photocatalytic process cannot effectively occur during sunlight irradiation. 4% of the total solar spectrum radiation is in the ultraviolet region.