Synergy effect in the photocatalytic degradation of pharmaceuticals on a suspended mixture of titania and activated carbon

Photocatalysis is currently being considered for many environmental applications such as water decontamination. This is due to its ability to degrade organic pollutants to CO₂, water and mineral acids. In TiO₂ photocatalysis, UV radiation is needed to create hole-electron pairs which can be transferred to water to form oxidizing species. However this process generally suffers low apparent quantum yield, mainly due to the rapid recombination of the photogenerated electron-holes. In order to improve quantum yields, the addition of activated carbon (AC) has been suggested. As adsorption is a key point in photocatalysis, the addition of AC can aid to increase pollutant's degradation kinetics by augmenting their adsorption onto the TiO₂-AC interphase. Carbon has also been suggested to act as an electron sink which may retard the recombination of electron-hole pairs. The aim of our work is to study the synergistic effect of TiO₂-AC on the removal of five different pharmaceuticals from water. Two different ACs were tested to identify the best working conditions. Different routes to combine TiO₂-AC were as well studied. Experiments under the following conditions: UV+TiO₂, UV+AC and UV+TiO₂+AC were performed in order to determine % of removal by photocatalysis, adsorption and by the synergistic effect of TiO₂-AC. Drugs degradation in a real matrix such as river water, and not only in ultrapure water, was also investigated.