Photocatalytic degradation of p-coumaric acid over TiO2 suspensions.

The photocatalytic degradation of p-coumaric acid, a biorecalcitrant phenolic compound typically found in olive processing and wine distillery waste waters, has been investigated in aqueous heterogeneous solutions containing semiconductor powders as photocatalysts. The disappearance of the organic molecule follows approximately a pseudo-first kinetic order according to the Langmuir-Hinselwood model. The most important reaction intermediates were determined by GS-MS and HPLC measurements, suggesting a reaction pathway for the photodegradation. Various commercial photocatalysts were compared with respect to their overall efficiency, as well as the production of CO2. The effect of H2O2 on the reaction rate was ascertained.