Laser photo-oxidative degradation of 4,6-dimethyldibenzothiophene

Mechanisms of oxidation of organosulfur compounds by ferrate(VI)

The oxidation of organosulfur compounds requires the transfer of oxygen atoms and is important in decontamination of chemical warfare agents, desulfurization of fossil fuel for high quality, deodorization of wastewater and sludge, and remediation of industrial effluents. The kinetics of the oxidation of organosulfur compounds (sulfur-containing amino acids, aliphatic and aromatic thiols, and mercaptans) by the environmentally-friendly oxidant, ferrate(VI) FeO(4)(2-), was quantitatively examined in this study using a kinetic model considering possible reactions among the species of ferrate(VI) and organosulfur compounds. The ratios of ferrate(VI) to the various organosulfur compounds for the one oxygen-atom transfer were 0.50 and 0.67 for Fe(II) and Fe(III) as final products, respectively. The second-order rate constants for the oxidation of organosulfur compounds by protonated ferrate(VI) HFeO(4)(-) ion were correlated with thermodynamic 1-e(-) and 2-e(-) reduction potentials in order to understand the mechanisms of the reactions. The oxidation of the compounds involved a 1-e(-) transfer step from Fe(VI) to Fe(V), followed by 2-e(-) transfer to Fe(III) as the reduced product (Fe(VI)→Fe(V)→Fe(III)). The 2-e(-) transfer steps resulted in the formation of Fe(II) (Fe(VI)→Fe(IV)→Fe(II)). Conclusions drawn from the correlations are consistent with the experimentally determined stoichiometries and products of the reactions. The calculated half-lives for the oxidation were in the range of ms to s at a dose of 10mg K(2)FeO(4)L(-1) and hence ferrate(VI) has a great potential in treating organosulfur compounds present in water and wastewater.

Photochemical and Electrochemical Oxygenation of Thiophenes, Benzo[b]Thiophenes and Dibenzothiophenes; Photochemical and Electrochemical Behaviour of Their Oxygenated Intermediates and Products

The photooxygenation of thiophenes, benzo[ b]thiophenes and dibenzothiophenes is discussed, especially in view of the oxidative removal of these S-containing contaminants from fuels. Furthermore, the photochemistry of the intermediates and the products from these processes is detailed. Finally, an account is given of the electrooxidation of thiophenes and derivatives to the corresponding sulfoxides and sulfones as well as of the electrochemical behaviour of the intermediate thiophene S-oxides.