Photooxidation of 4-chlorophenol sensitised by iron meso-tetrakis(2,6-dichloro-...

• Autor(es): Silva, Eliana ; Pereira, Mariette M. ; Burrows, Hugh D. ; Azenha, M. E. ; Sarakha, Mohamed ; Bolte, Michèle
• Data: 2003
• Identificador Persistente: http://hdl.handle.net/10316/10726
• Origem: Estudo Geral - Universidade de Coimbra
• Tipo de Documento: Artigo
• Idioma: Inglês

Descrição

The photosensitised degradation of 4-chlorophenol (4-CP) by iron meso-tetrakis(2,6-dichloro-3-sulfophenyl)porphyrin (FeTDCPPS) has been studied in aerated aqueous solution, and is shown to lead to formation of p-benzoquinone (BQ) and p-hydroquinone (HQ) as main photoproducts. In deaerated solution no p-benzoquinone was formed. The photolysis products were identified by high performance liquid chromatography (HPLC) and UV-visible spectroscopy. The photodegradation in aerated solution was also carried out in the presence of sodium azide (NaN3) as a singlet oxygen [1O2(1g)] quencher, and showed a significant decrease in the rate of photolysis, suggesting under these conditions, that Type II sensitisation is one of the dominant mechanisms of 4-CP degradation. Support for this comes from laser flash photolysis and time-resolved singlet oxygen phosphorescence measurements. However, these also show direct reaction between the excited porphyrin and 4-CP, indicating that there are two mechanisms involved in the chlorophenol photodegradation. http://dx.doi.org/10.1039/b308975d Clermont-Ferrand; ICCTI/GRICES; CNRS; FCT; POCTI; FEDER