Adsorption and photocatalytic degradation of 2,4-dichlorophenol in TiO2 suspensions. Effect of hydrogen peroxide, sodium peroxodisulphate and ozone

Authors:  E. Pulido Melián, O. González Díaz, J.M. Doña Rodríguez, J. Araña, J. Pérez Peña

Abstract:
2,4-dichlorophenol (DCP) was decomposed in the presence of TiO₂ suspensions by illumination. The operating variables that were studied included initial DCP concentration, photocatalyst doses and initial pH. Mineralisation was slow at the optimum pH (12) for DCP degradation, with the optimum pH for both degradation and mineralisation being pHo 5. The kinetic patterns were fitted to a first order kinetic. Adsorption and rate constants were obtained by using the Langmuir–Hinshelwood model. The adsorption isotherm was fitted to the Freundlich model and the Langmuir model with high coefficients of correlation. The adsorptionconstantindarkness was lower thanthat obtained withthe kineticmodel.According to the FTIR results, DCP–TiO₂ interaction occurs as a result of the formation of a phenolate. Of the three oxidants tested – hydrogen peroxide, ozone and sodium peroxodisulphate – only H₂O₂ resulted in enhancement of the photocatalytic process.

Keywords:
Photocatalysis
TiO₂, 2,4-dichlorophenol
Hydrogen peroxide
Ozone
Peroxodisulphate

Published in: Applied catalysis A: General  (Volume 455, Pages 1-266, 30 March 2013)

Publisher: Elsevier

ISSN Information: 0926-860X

Adsorption and photocatalytic degradation of 2,4-dichlorophenol in TiO2 suspensions. Effect of hydrogen peroxide, sodium peroxodisulphate and ozone

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