The nature of chlorine-inhibition of photocatalytic degradation of dichloroacetic acid in a TiO sub(2)-based microreactor

Photocatalytic degradation of dichloroacetic acid (DCA) was studied in a continuous-flow set-up using a titanium microreactor with an immobilized double-layered TiO sub(2) nanoparticle/nanotube film. Chloride ions, formed during the degradation process, negatively affect the photocatalytic efficienc...

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Bibliographic Details
Published in:Physical chemistry chemical physics : PCCP 2014-06, Vol.16 (28), p.14867-14873
Main Authors: Krivec, M, Dillert, R, Bahnemann, D W, Mehle, A, Strancar, J, Drazic, G
Format: Article
Language:English
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Summary:Photocatalytic degradation of dichloroacetic acid (DCA) was studied in a continuous-flow set-up using a titanium microreactor with an immobilized double-layered TiO sub(2) nanoparticle/nanotube film. Chloride ions, formed during the degradation process, negatively affect the photocatalytic efficiency and at a certain concentration (approximately 0.5 mM) completely stop the reaction in the microreactor. Two proposed mechanisms of inhibition with chloride ions, competitive adsorption and photogenerated-hole scavenging, have been proposed and investigated by adsorption isotherms and electron paramagnetic resonance (EPR) measurements. The results show that chloride ions block the DCA adsorption sites on the titania surface and reduce the amount of adsorbed DCA molecules. The scavenging effect of chloride ions during photocatalysis through the formation of chlorine radicals was not detected.
ISSN:1463-9076
1463-9084
DOI:10.1039/c4cp01043d