Semiconductor under UV light
The project PHOTOPUR aims to use the properties of semiconductors under UV-irradiation to destroy pesticides being dissolved in water. In semiconductors, such as e.g. titanium dioxide, the energy of UV-light carries electrons from the valence band onto the conduction band. This process produces defect electrons (also called electron holes). These, in turn, can split the surrounding water molecules into a hydroxyl radical and a proton.
Radicals destroying pesticides
The resulting radicals then react with other organic molecules in the surrounding water, for example with pesticide molecules. Theoretically, a complete mineralization of the pesticide can be achieved by this process.
Thus, within PHOTOPUR, contaminated water becomes clean water again, which can subsequently be introduced into the municipal wastewater or directly into the receiving water.