Photocatalytic Removal of Pesticide Dichlorvos from Indoor Air: A Study of Reaction Parameters, Intermediates and Mineralization

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• 作者：Mohamad Sleiman ; Corinne Ferronato ; Jean-Marc Chovelon
• 刊名：Environmental Science & Technology
• 出版年：2008
• 出版时间：April 15, 2008
• 年：2008
• 卷：42
• 期：8
• 页码：3018 - 3024
• 全文大小：290K
• 年卷期：v.42,no.8(April 15, 2008)
• ISSN：1520-5851

文摘

This paper presents for the first time the investigation of TiO₂ photocatalysis for the removal of pesticides in gas phase. Dichlorvos was used as a model pesticide, and experiments were carried out using both static and dynamic reaction systems to explore the different aspects of the process. Thus, adsorption, reaction kinetics, and the influence of several operational parameters such as relative humidity (RH), inlet concentration, flow rate, and association of TiO₂ with activated carbon (AC) were all examined in detail. Furthermore, a special attention was devoted to the analysis of reaction products by means of various analytical techniques such as Fourier transform infrared spectroscopy, automated thermal desorption technique coupled to gas chromatography–mass spectrometry instrument, gas chromatography equipped with a pulse discharge helium photoionization detector, and ion chromatography. The results showed an immediate and total removal of dichlorvos at ppbv levels (50–350 ppbv) along with a high mineralization extent (50–85%) into harmless final products (CO₂, HCl, PO₄³⁻). Moreover, RH was found to significantly affect the mineralization extent and the formation of reaction intermediates. On the basis of identification data, direct charge transfer and chlorine radical (Cl^•) attack were shown to play a key role in the reaction mechanism at low RH, whereas at high RH, HO^• radicals were the predominant active species.