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

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dc.identifier.uri http://dx.doi.org/10.15488/3375
dc.identifier.uri http://www.repo.uni-hannover.de/handle/123456789/3405
dc.contributor.author Atitar, M. Faycal
dc.contributor.author Bouziani, Asmae
dc.contributor.author Dillert, Ralf
dc.contributor.author El Azzouzi, Mohamed
dc.contributor.author Bahnemann, Detlef W.
dc.date.accessioned 2018-05-23T08:43:21Z
dc.date.available 2018-05-23T08:43:21Z
dc.date.issued 2018
dc.identifier.citation Atitar, M.F.; Bouziani, A.; Dillert, R.; El Azzouzi, M.; Bahnemann, D.W.: Photocatalytic degradation of the herbicide imazapyr: Do the initial degradation rates correlate with the adsorption kinetics and isotherms?. In: Catalysis Science and Technology 8 (2018), Nr. 4, S. 985-995. DOI: https://doi.org/10.1039/c7cy01903c
dc.description.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 TiO2 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 TiO2 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 TiO2 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. © 2018 The Royal Society of Chemistry. eng
dc.language.iso eng
dc.publisher Cambridge : Royal Society of Chemistry
dc.relation.ispartofseries Catalysis Science and Technology 8 (2018), Nr. 4
dc.rights CC BY-NC 3.0
dc.rights.uri https://creativecommons.org/licenses/by-nc/3.0/
dc.subject Adsorption eng
dc.subject Degradation eng
dc.subject Herbicides eng
dc.subject Irradiation eng
dc.subject Kinetics eng
dc.subject Phosphorus compounds eng
dc.subject Rate constants eng
dc.subject Reaction kinetics eng
dc.subject Suspensions (fluids) eng
dc.subject Titanium dioxide eng
dc.subject Weed control eng
dc.subject Adsorption kinetics and isotherm eng
dc.subject Initial concentration eng
dc.subject Initial degradation rate eng
dc.subject Langmuir Hinshelwood mechanism eng
dc.subject Langmuir-Hinshelwood models eng
dc.subject Photo catalytic degradation eng
dc.subject Reactant concentrations eng
dc.subject Second-order reaction eng
dc.subject Reaction rates eng
dc.subject.ddc 540 | Chemie ger
dc.title Photocatalytic degradation of the herbicide imazapyr: Do the initial degradation rates correlate with the adsorption kinetics and isotherms?
dc.type article
dc.type Text
dc.relation.issn 2044-4753
dc.relation.doi https://doi.org/10.1039/c7cy01903c
dc.bibliographicCitation.issue 4
dc.bibliographicCitation.volume 8
dc.bibliographicCitation.firstPage 985
dc.bibliographicCitation.lastPage 995
dc.description.version publishedVersion
tib.accessRights frei zug�nglich


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