Abstract
In the context of the increase in chemical threat due to warfare agents, the development of efficient methods for destruction of Chemical Warfare Agents (CWAs) are of first importance both for civilian and military purposes. Amongst possible methods for destruction of CWAs, photocatalytic oxidation is an alternative one. The present paper reports on the preparation of Ta and Sn doped TiO2 photocatalysts immobilized on β-SiC foams for the elimination of diethyl sulfide (DES) used as a model molecule mimicking Yperite (Mustard Gas) in gaseous phase. Photo-oxidation efficiency of doped TiO2 catalyst has been compared with TiO2-P25. Here, we demonstrate that the Sn doped-TiO2 with a Polyethylene glycol (PEG)/TiO2 ratio of 7 exhibits the best initial activity (up to 90%) but is deactivates more quickly than Ta doped-TiO2 (40% after 800 min). The activity of the catalysts is strongly influenced by the adsorption properties of the support, as β-SiC foams adsorb DES and other sulfur compounds. This adsorption makes it possible to limit the poisoning of the catalysts and to maintain an acceptable conversion rate even after ten hours under continuous DES flow. Washing with NaOH completely regenerates the catalyst after a firs treatment and even seems to “wash” it by removing impurities initially present on the foams.
Highlights
Chloroethylethylsulfide (CEES) [11,12], and diethyl sulfide (DES) [13] are the most used in photocatalytic elimination of Chemical Warfare Agents (CWAs)
The present paper reports on the preparation of Ta and Sn doped TiO2 photocatalysts immobilized on β-SiC foams for the elimination of Diethyl sulfide (DES) in gaseous phase
The results show that the two tests with 1 foam piece are similar and reproducible after 80 min, which corresponds to the equilibrium time of adsorption and desorption of DES on the photocatalytic material
Summary
Amongst possible methods for destruction of CWAs, photocatalytic oxidation is an alternative one [8,9]. Chloroethylethylsulfide (CEES) [11,12], and diethyl sulfide (DES) [13] are the most used in photocatalytic elimination of CWAs. TiO2 is often considered as being one of the best candidates for using a photocatalyst for oxidation applications under UV-A light. Total mineralization of sulfur- or organo-sulfur compounds leading to the formation of sulfates deposited onto the surface generally ended to TiO2 deactivation. To overcome this important limitation, strategies of increasing TiO2 surface area by Ta or Sn-doping have been investigated and resulted in strongly hindering
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