Highly concentrated phenolic wastewater treatment by heterogeneous and homogeneous photocatalysis: mechanism study by FTIR-ATR

The degradation of high phenol concentrations (1 g/L) in water solutions by TiO2 photocatalysis and the photo-Fenton reaction has been studied. From t he obtained data it may be suggested that degradation of phenol by TiO2-UV takes place onto the catalyst surface by means of peroxo-compounds formatio n. At low phenol concentrations other mechanism, the insertion of OHcircle radicals, may be favored, On the other hand, highly concentrated phenol aqu eous solutions treatment by the photo-Fenton reaction gives rise to the for mation of polyphenolic polymers. These seem to reduce the process rate. Deg radation intermediates have been identified by HPLC and FTIR. The FTIR stud y of the catalyst surface has shown infrared bands attributable to differen t chemisorbed peroxo-compounds, formates, ortho-formates and carboxylates t hat can inactivate the catalyst.