Chlorinated Aromatic Compounds in a Thermal Process Promoted by Oxychlorination of Ferric Chloride

Abstract

The relationship between the formation of chlorinated aromatic (aromatic-Cl) compounds and ferric chloride in the solid phase during a thermal process motivated us to study the chemical characteristics of iron in a model solid sample, a mixture of FeCl(3) x 6H(2)O, activated carbon, and boron nitride, with increasing temperature. Fe K-edge extended X-ray absorption fine structure (EXAFS) spectroscopy revealed drastic changes in the chemical form of amorphous iron, consistent with other analytical methods, such as X-ray diffraction using synchrotron radiation (SR-XRD) and Fourier-transform infrared (FT-IR) spectroscopy. Atomic-scale evidence of the chlorination of aromatic carbon was detected by Cl-K X-ray absorption near edge structure (XANES) spectroscopy. These results showed the thermal formation mechanism of aromatic-Cl compounds in the solid phase with ferric chloride. We attribute the formation of aromatic-Cl compounds to the chlorination of carbon, based on the oxychlorination reaction of FeCl(3) at temperatures in excess of ca. 300 degrees C, when the carbon matrix is activated by carbon gasification, catalyzed by Fe(2)O(3), and surface oxygen complexes (SOC) generated by a catalytic cycle of FeCl(2) and FeOCl. Chemical changes of trace iron in a thermal process may offer the potential to generate aromatic-Cl compounds in the solid phase.

The Environmental Photochemistry of Oxide Surfaces and the Nature of Frozen Salt Solutions: A New in Situ XPS Approach

“…Dry NaCl, spectrum (A), shows a main absorption peak at 2825.0 eV, corresponding to the transition from 1s to 4p orbitals [55], and a typical post-edge feature [56] at 2836.0 eV. The preedge peak at 2820.8 eV can be attributed to C-Cl bonds [57] due to carbon contamination of the sample, as sizeable amounts of NaOCl, showing an absorption peak at a similar photon energy [58], can be excluded. The NEXAFS spectrum of the frozen NaCl solution (B) is quite different compared to that of the solid phase being characterized by a broader edge with two components.…”

Formation of dioxins on NiO and NiCl2 at different oxygen concentrations

“…The spectra of both reference materials and fly ash were measured to compare their spectral shapes and to identify the major species present. The linear combination fit (LCF) of the XANES spectra has several times been used to identify and quantify major species in particulate matter or incinerator bottom ash (Ressler et al, 2000;Hsiao et al, 2001;Takaoka et al, 2005Takaoka et al, , 2010Fujimori et al, 2010Fujimori et al, , 2011. LCF can determines the proportions of the spectra for selected standards that, when summed, yield the least fit to the spectrum of an unknown sample.…”

“…Gullett et al (1992), Oehme et al (1989) and Öberg et al (2007) suggested that nickel compounds could also play a role in the catalytic formation of PCDD/Fs. Recently, X-ray absorption near edge structural (XANES) spectroscopy has been used to monitor redox changes of copper, iron and zinc during dioxin formation (Takaoka et al, 2005Fujimori et al, 2010Fujimori et al, , 2011. This technique will further be used to monitor the speciation of nickel after its reaction in MFA doped with either NiCl 2 or NiO.…”

Production of Persistent Organic Pollutants from Cement Plants

“…In the precursor mechanism there will be the polycondensation of precursor. Usually these gaseous reactions will take place in the range between 300-600 o C. In the de novo synthesis, carbon must be present at the solid phase; on the other hand, the presence of oxygen in the gas phase is also fundamental (Fujimori et al, 2010). Usually these reactions take place at 200-400 o C.…”