Photocatalytic oxidation of diethyl sulfide vapor over TiO2-based composite photocatalysts.

Dmitry Selishchev,Denis Kozlov

doi:10.3390/molecules191221424

Dmitry Selishchev, Denis Kozlov

Open Access

https://doi.org/10.3390/molecules191221424

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Abstract

Composite TiO2/activated carbon (TiO2/AC) and TiO2/SiO2 photocatalysts with TiO2 contents in the 10 to 80 wt. % range were synthesized by the TiOSO4 thermal hydrolysis method and characterized by AES, BET, X-ray diffraction and FT-IR ATR methods. All TiO2 samples were in the anatase form, with a primary crystallite size of about 11 nm. The photocatalytic activities of the TiO2/AC and TiO2/SiO2 samples were tested in the gas-phase photocatalytic oxidation (PCO) reaction of diethyl sulfide (DES) vapor in a static reactor by the FT-IR in situ method. Acetaldehyde, formic acid, ethylene and SO2 were registered as the intermediate products which finally were completely oxidized to the final oxidation products – H2O, CO2, CO and SO42− ions. The influence of the support on the kinetics of DES PCO and on the TiO2/AC and TiO2/SiO2 samples’ stability during three long-term DES PCO cycles was investigated. The highest PCO rate was observed for TiO2/SiO2 photocatalysts. To evaluate the activity of photocatalysts the turnover frequency values (TOF) were calculated for three photocatalysts (TiO2, TiO2/AC and TiO2/SiO2) for the same amount of mineralized DES. It was demonstrated that the TOF value for composite TiO2/SiO2 photocatalysts was 3.5 times higher than for pure TiO2.

Highlights

Volatile organic compounds containing N, S, P or Cl heteroatoms are often highly toxic and very dangerous for human health [1,2,3], and some of them could be used as chemical warfare agents (CWA) [4]
Synthesis of TiO2, TiO2/activated carbon (TiO2/activated carbon (AC)) and TiO2/SiO2 samples was performed by the TiOSO4 thermal hydrolysis method
Varying the TiO2 content in the series of TiO2/adsorbent samples allows us to choose a photocatalyst with high adsorption capacity and at the same time with high photocatalytic activity for further investigation of diethyl sulfide (DES) photocatalytic oxidation (PCO)

Summary

Introduction

Volatile organic compounds containing N, S, P or Cl heteroatoms are often highly toxic and very dangerous for human health [1,2,3], and some of them could be used as chemical warfare agents (CWA) [4]. One of the best known CWAs is bis(2-chloroethyl) sulfide or mustard gas (HD) This species is a highly toxic vesicant which causes destruction of cell membranes and nucleic acids. It binds with nucleophilic groups like sulphur atoms in the SH-groups of proteins and nitrogen atoms in the nitrogen bases of DNA [5]. The relative toxicity (LD50) for HD inhalation is about 1.5 mg·min/L and this value is the highest among vesicants [6]. In this way the development of effective methods for HD neutralization is an important task to ensure human safety

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