Photocatalytic degradation of the herbicide imazapyr: Do the initial degradation rates correlate with the adsorption kinetics and isotherms?

Publikation: Beitrag in Fachzeitschrift › Artikel › Forschung › Peer-Review

Autoren

  • Mohamed Faycal Atitar
  • Asmae Bouziani
  • Ralf Dillert
  • Mohamed El Azzouzi
  • Detlef W. Bahnemann

Organisationseinheiten

Externe Organisationen

  • Mohammed V University in Rabat
  • Staatliche Universität Sankt Petersburg
Forschungs-netzwerk anzeigen

Details

OriginalspracheEnglisch
Seiten (von - bis)985-995
Seitenumfang11
FachzeitschriftCatalysis Science and Technology
Jahrgang8
Ausgabenummer4
Frühes Online-Datum14 Dez. 2017
PublikationsstatusVeröffentlicht - 21 Feb. 2018

Abstract

The objective of this work is to correlate the photocatalytic degradation of the herbicide imazapyr in aqueous suspensions of the commercially available Evonik Aeroxide TiO 2 P25 with the dark adsorption phenomena considering both the equilibrium state and the kinetics of adsorption. The results of this study show that the adsorption of imazapyr onto the TiO 2 surface is a second-order reaction and satisfies the criteria required by the Langmuir model. The adsorbed amount of imazapyr is found to be high at pH 3 and to decrease with increasing pH. The kinetics of the photocatalytic degradation of imazapyr were analysed taking into account the effect of the pH as well as of the catalyst mass concentration. However, special attention was focussed on the influence of the reactant concentration on the reaction rate. The Langmuir-Hinshelwood model fitting revealed that the apparent adsorption constant obtained under irradiation is significantly larger than the adsorption constant obtained in the dark. The initial reaction rates of the photocatalytic imazapyr degradation were larger than the initial adsorption rates of the probe molecule on the TiO 2 surface. It is therefore concluded that the photocatalytic imazapyr degradation does not follow necessarily a Langmuir-Hinshelwood mechanism despite the fact that a rate law having the mathematical form of the Langmuir-Hinshelwood rate law was successfully used to describe the observed dependence of the initial reaction rates on the initial concentrations. A Langmuir-Hinshelwood mechanism for the photocatalytic imazapyr degradation is compatible only with the additional assumption that the rate constant of adsorption increases by irradiation with UV light.

ASJC Scopus Sachgebiete

  • Chemische Verfahrenstechnik (insg.)
  • Katalyse

Zitieren

Photocatalytic degradation of the herbicide imazapyr: Do the initial degradation rates correlate with the adsorption kinetics and isotherms? / Atitar, Mohamed Faycal; Bouziani, Asmae; Dillert, Ralf et al.
in: Catalysis Science and Technology, Jahrgang 8, Nr. 4, 21.02.2018, S. 985-995.

Publikation: Beitrag in Fachzeitschrift › Artikel › Forschung › Peer-Review

Atitar MF, Bouziani A, Dillert R, El Azzouzi M, Bahnemann DW. Photocatalytic degradation of the herbicide imazapyr: Do the initial degradation rates correlate with the adsorption kinetics and isotherms? Catalysis Science and Technology. 2018 Feb 21;8(4):985-995. Epub 2017 Dez 14. doi: 10.1039/c7cy01903c
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title = "Photocatalytic degradation of the herbicide imazapyr: Do the initial degradation rates correlate with the adsorption kinetics and isotherms?",
abstract = "The objective of this work is to correlate the photocatalytic degradation of the herbicide imazapyr in aqueous suspensions of the commercially available Evonik Aeroxide TiO 2 P25 with the dark adsorption phenomena considering both the equilibrium state and the kinetics of adsorption. The results of this study show that the adsorption of imazapyr onto the TiO 2 surface is a second-order reaction and satisfies the criteria required by the Langmuir model. The adsorbed amount of imazapyr is found to be high at pH 3 and to decrease with increasing pH. The kinetics of the photocatalytic degradation of imazapyr were analysed taking into account the effect of the pH as well as of the catalyst mass concentration. However, special attention was focussed on the influence of the reactant concentration on the reaction rate. The Langmuir-Hinshelwood model fitting revealed that the apparent adsorption constant obtained under irradiation is significantly larger than the adsorption constant obtained in the dark. The initial reaction rates of the photocatalytic imazapyr degradation were larger than the initial adsorption rates of the probe molecule on the TiO 2 surface. It is therefore concluded that the photocatalytic imazapyr degradation does not follow necessarily a Langmuir-Hinshelwood mechanism despite the fact that a rate law having the mathematical form of the Langmuir-Hinshelwood rate law was successfully used to describe the observed dependence of the initial reaction rates on the initial concentrations. A Langmuir-Hinshelwood mechanism for the photocatalytic imazapyr degradation is compatible only with the additional assumption that the rate constant of adsorption increases by irradiation with UV light. ",
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T1 - Photocatalytic degradation of the herbicide imazapyr: Do the initial degradation rates correlate with the adsorption kinetics and isotherms?

AU - Atitar, Mohamed Faycal

AU - Bouziani, Asmae

AU - Dillert, Ralf

AU - El Azzouzi, Mohamed

AU - Bahnemann, Detlef W.

N1 - Funding information: Mohamed Faycal Atitar gratefully acknowledges a scholarship from the DAAD in the frame of the Sandwich-Program. Financial support of the BMBF in the framework of an international collaboration between Morocco and Germany is gratefully acknowledged (FKZ: 01DH12028).

PY - 2018/2/21

Y1 - 2018/2/21

N2 - The objective of this work is to correlate the photocatalytic degradation of the herbicide imazapyr in aqueous suspensions of the commercially available Evonik Aeroxide TiO 2 P25 with the dark adsorption phenomena considering both the equilibrium state and the kinetics of adsorption. The results of this study show that the adsorption of imazapyr onto the TiO 2 surface is a second-order reaction and satisfies the criteria required by the Langmuir model. The adsorbed amount of imazapyr is found to be high at pH 3 and to decrease with increasing pH. The kinetics of the photocatalytic degradation of imazapyr were analysed taking into account the effect of the pH as well as of the catalyst mass concentration. However, special attention was focussed on the influence of the reactant concentration on the reaction rate. The Langmuir-Hinshelwood model fitting revealed that the apparent adsorption constant obtained under irradiation is significantly larger than the adsorption constant obtained in the dark. The initial reaction rates of the photocatalytic imazapyr degradation were larger than the initial adsorption rates of the probe molecule on the TiO 2 surface. It is therefore concluded that the photocatalytic imazapyr degradation does not follow necessarily a Langmuir-Hinshelwood mechanism despite the fact that a rate law having the mathematical form of the Langmuir-Hinshelwood rate law was successfully used to describe the observed dependence of the initial reaction rates on the initial concentrations. A Langmuir-Hinshelwood mechanism for the photocatalytic imazapyr degradation is compatible only with the additional assumption that the rate constant of adsorption increases by irradiation with UV light.

AB - The objective of this work is to correlate the photocatalytic degradation of the herbicide imazapyr in aqueous suspensions of the commercially available Evonik Aeroxide TiO 2 P25 with the dark adsorption phenomena considering both the equilibrium state and the kinetics of adsorption. The results of this study show that the adsorption of imazapyr onto the TiO 2 surface is a second-order reaction and satisfies the criteria required by the Langmuir model. The adsorbed amount of imazapyr is found to be high at pH 3 and to decrease with increasing pH. The kinetics of the photocatalytic degradation of imazapyr were analysed taking into account the effect of the pH as well as of the catalyst mass concentration. However, special attention was focussed on the influence of the reactant concentration on the reaction rate. The Langmuir-Hinshelwood model fitting revealed that the apparent adsorption constant obtained under irradiation is significantly larger than the adsorption constant obtained in the dark. The initial reaction rates of the photocatalytic imazapyr degradation were larger than the initial adsorption rates of the probe molecule on the TiO 2 surface. It is therefore concluded that the photocatalytic imazapyr degradation does not follow necessarily a Langmuir-Hinshelwood mechanism despite the fact that a rate law having the mathematical form of the Langmuir-Hinshelwood rate law was successfully used to describe the observed dependence of the initial reaction rates on the initial concentrations. A Langmuir-Hinshelwood mechanism for the photocatalytic imazapyr degradation is compatible only with the additional assumption that the rate constant of adsorption increases by irradiation with UV light.

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