Studies on the mechanism of the peroxyoxalate chemiluminescence reaction : part 2, further identification of intermediates using 2D EXSY 13C nuclear magnetic resonance spectroscopy

Further consideration has been given to the reaction pathway of a model peroxyoxalate chemiluminescence system. Again utilising doubly labelled oxalyl chloride and anhydrous hydrogen peroxide, 2D EXSY ¹³C nuclear magnetic resonance (NMR) spectroscopy experiments allowed for the characterisation of unknown products and key intermediate species on the dark side of the peroxyoxalate chemiluminescence reaction. Exchange spectroscopy afforded elucidation of a scheme comprised of two distinct mechanistic pathways, one of which contributes to chemiluminescence. ¹³C NMR experiments carried out at varied reagent molar ratios demonstrated that excess amounts of hydrogen peroxide favoured formation of 1,2-dioxetanedione: the intermediate that, upon thermolysis, has been long thought to interact with a fluorophore to produce light.

Qualitative spectroscopic characterization of the matrix-silane coupling agent interface across metal fibre reinforced ion exchange resin composite membranes

The characterization of novel metal reinforced electro-dialysis ion exchange membranes, for water desalination, by attenuated total reflectance Fourier transform infrared spectroscopy mapping is presented in this paper. The surface of the porous stainless steel fibre meshes was treated in order to enhance the amount of surface oxide groups and increase the material hydrophilicity. Then, the metal membranes were functionalized through a sol-gel reaction with silane coupling agents to enhance the affinity with the ion exchange resins and avoid premature metal oxidation due to redox reactions at the metal-polymer interface. Polished cross sections of the composite membranes embedded into an epoxy resin revealed interfaces between metallic frameworks and the silane layer at the interface with the ion exchange material. The morphology of the metal-polymer interface was investigated with scanning electron microscopy and Fourier transform infrared micro-spectroscopy. Fourier transform infrared mapping of the interfaces was performed using the attenuated total reflectance mode on the polished cross-sections at the Australian Synchrotron. The nature of the interface between the metal framework and the ion exchange resin was shown to be homogeneous and the coating thickness was found to be around 1 μm determined by Fourier transform infrared micro-spectroscopy mapping. The impact of the coating on the properties of the membranes and their potential for water desalination by electro-dialysis are also discussed.