Photocatalytic Degradation of Persistent Organic Pollutants

This project is in the field of environmental science and technology, and involves the inter-disciplines of environmental science, chemistry and material science.

Toxic organic pollutants, such as chlorinated compounds, pesticides and dyes, are serious environmental concerns worldwide. These chemical species are often non-biodegradable and many of them are carcinogenic even at trace concentrations. Conventional physiochemical and biological treatment methods are generally not totally effective. Therefore, it is important to explore novel methods for efficient elimination of toxic organic pollutants. Photocatalysis is an emerging technology which uses environmentally-friendly oxidants (oxygen, hydrogen peroxide or ozone), photocatalyst (titanium dioxide, ferrous ions or its complexes) and ultraviolet (UV) radiation to degrade and mineralize the toxic organic pollutants. The major drawback is that photocatalytic processes need to be activated by ultraviolet light, which accounts for only 3-5% of the solar spectrum; and the overall reaction efficiency is still very low. The objective of this project was to develop visible-light photocatalytic systems for the efficient degradation of toxic organic pollutants. The success of this project is critical for the future development of solar energy based pollution treatment systems:

(1) Visible-light was effectively utilized to degrade and mineralize dye pollutants in TiO2 dispersions. Mechanisms different from the UV-induced degradation were proposed.
(2) A series of visible-light-active Fe-N complexes were designed and synthesized. Upon visible light irradiation, these complexes could effectively activate H2O2 or O2 for the removal of organic pollutants.
(3) A new class of binary-doped TiO2-based photocatalyst (Ni2O3/TiO2-xBx) was fabricated. When irradiated with visible-light, this catalyst could initiate the destruction of chlorophenols by oxidation.

Over the past 9 years, Professor Jimmy Yu and his collaborator Professor Zhao Jincai have conducted systematic investigations involving modified TiO2 to clarify the fundamental issues in photocatalysis. Their contributions are documented in over 100 papers in leading journals. Professor Yu has also obtained six patents for the technology he developed.