The effect of hexadecyltrimethylammonium bromide (HTAB) on the photocatalytic degradation of phenol (Phe), 2,5-dichlorophenol (2,5- DCP) and 2,4,5-trichlorophenol (2,4,5-TCP) in the presence of aqueous TiO2 suspensions at pH ca. 5 was investigated using a laboratory photoreactor equipped with a medium-pressure mercury lamp. Inhibition of substrate decomposition was observed for phenol, both below and above the surfactant critical micellar concentration, whereas a more complex behaviour was exhibited by chlorophenols. It was found that adsorption of these compounds onto the surfactant-modified semiconductor particles facilitates their faster decomposition, but the competitive partition of substrates between adsorbed surfactant structures and micellar aggregates tends to limit the beneficial kinetic effects at higher amphiphile concentrations. The crucial influence of surfactant adsorption was clearly evidenced in some runs performed at pH 3. Relevant inhibition of chloride release from chlorophenols, observed in the presence of HTAB, indicates a higher persistence of reaction intermediates in the reaction media, suggesting the need for a careful investigation of surfactant effects on all the degradation steps of the process.

Effect of Surfactant Microstructures on Photocatalytic Degradation of Phenol and Chlorophenols

FABBRI, DEBORA;BIANCO PREVOT, Alessandra;PRAMAURO, Edmondo
2006

Abstract

The effect of hexadecyltrimethylammonium bromide (HTAB) on the photocatalytic degradation of phenol (Phe), 2,5-dichlorophenol (2,5- DCP) and 2,4,5-trichlorophenol (2,4,5-TCP) in the presence of aqueous TiO2 suspensions at pH ca. 5 was investigated using a laboratory photoreactor equipped with a medium-pressure mercury lamp. Inhibition of substrate decomposition was observed for phenol, both below and above the surfactant critical micellar concentration, whereas a more complex behaviour was exhibited by chlorophenols. It was found that adsorption of these compounds onto the surfactant-modified semiconductor particles facilitates their faster decomposition, but the competitive partition of substrates between adsorbed surfactant structures and micellar aggregates tends to limit the beneficial kinetic effects at higher amphiphile concentrations. The crucial influence of surfactant adsorption was clearly evidenced in some runs performed at pH 3. Relevant inhibition of chloride release from chlorophenols, observed in the presence of HTAB, indicates a higher persistence of reaction intermediates in the reaction media, suggesting the need for a careful investigation of surfactant effects on all the degradation steps of the process.
APPLIED CATALYSIS. B, ENVIRONMENTAL
62
21
27
Photocatalysis; Phenol; Chlorophenols; Surfactants; Microstructures
D. FABBRI; A. BIANCO PREVOT; E. PRAMAURO
File in questo prodotto:
File Dimensione Formato  
EFFECT_microstructures.pdf

non disponibili

Tipo di file: POSTPRINT (VERSIONE FINALE DELL’AUTORE)
Dimensione 188.04 kB
Formato Adobe PDF
188.04 kB Adobe PDF   Visualizza/Apri   Richiedi una copia
HTABchlorophenols 05_2_4aperto.pdf

accesso aperto

Tipo di file: POSTPRINT (VERSIONE FINALE DELL’AUTORE)
Dimensione 455.85 kB
Formato Adobe PDF
455.85 kB Adobe PDF Visualizza/Apri

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/2318/100994
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 69
  • ???jsp.display-item.citation.isi??? 68
social impact