Naslov
Effect of the structural change of an iron–iron oxide mixture on the decomposition of trichloroethylene

Autori
Kubuki, Shiro ; Shibano, Koya ; Akiyama, Kazuhiko ; Homonnay, Zoltan ; Kuzman, Erno ; Ristić, Mira ; Nishida, Tetsuaki

Izvornik
Journal of radioanalytical and nuclear chemistry (0236-5731) 295 (2013), 1; 23-40

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
trichloroethylene (TCE); gas chromatography; 57Fe-Mössbauer spectroscopy; zero valent iron (Fe0); maghemite; magnetite

Sažetak
The effect of the structure of a mixture of industrially produced iron and iron oxide on the decomposition of trichloroethylene (TCE) was investigated by gas chromatography, scanning electron microscopy, Fourier transform infrared spectroscopy, energy dispersive X-ray analysis, X-ray diffractometry, and 57Fe-Mössbauer spectroscopy. The concentration of 10 mg L−1 TCE aqueous solution decreased to 0.41, 0.52, 0.26, and 0.09 mg L−1 when stirred for 7 days with iron–iron oxide mixtures having mass ratios of 2:8, 3:7, 4:6, and 5:5, respectively. The Mössbauer spectra of the mixtures after leaching were composed of two sextets with respective isomer shifts (δ) and internal magnetic fields (H) of 0.29±0.01 mm s−1 and 48.8±0.1 T, and 0.64±0.01 mm s−1 and 45.5±0.1 T, attributed to the Fe3+ species in tetrahedral (T d) and the Fe2+ and Fe3+ mixed species (Fe2.5+) in octahedral (O h) sites, respectively. Mössbauer spectra of a 3:7 mass ratio iron–iron oxide mixture showed a gradual decrease in the absorption area (A) of zero valent iron (Fe0) from 40.6. to 12.6, 13.2, 3.8 2.8, and 1.0±0.5 % and an increase in A of Fe3O4 from 31.8 to 59.4, 71.4, 93.2, 95.6, and 98.0±0.5 % after leaching with 10 mg L−1 TCE aqueous solution for 1, 2, 3, 7, and 10 days, respectively. Consistent values of the first-order rate constant were calculated as 0.32 day−1 for Fe0 oxidation, 0.34 day−1 for Fe3O4 production, and 0.30 day−1 for TCE decomposition, which indicates that the oxidation of Fe0 was the rate-controlling factor for Fe3O4 production and TCE decomposition. It is concluded from the experimental results that an iron–iron oxide mixture is very effective for the decomposition of TCE.

Izvorni jezik
Engleski

Znanstvena područja
Kemija

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