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Chromate removal as influenced by the structural changes of soil components upon carbonization at different temperatures

Author:
Chen, K.Y., Liu, J.C., Chiang, P.N., Wang, S.L., Kuan, W.H., Tzou, Y.M., Deng, Y., Tseng, K.J., Chen, C.C., Wang, M.K.
Source:
Environmental pollution 2012 v.162 pp. 151-158
ISSN:
0269-7491
Subject:
Fourier transform infrared spectroscopy, air, carbon, carbonization, chromium, heat, nuclear magnetic resonance spectroscopy, potassium chloride, soil organic matter, temperature
Abstract:
Surface fire could induce heat transferring into the soil, creating a carbonized environment, which may alter the chemical compositions of soil organic matters (SOM). In the study, a surface soil was carbonized at up to 600 °C with limited air to simulate soils experiencing a surface fire, and Cr(VI) removal on the carbonized soils was investigated. NMR and FTIR analyses demonstrated a remarkable change of SOM structures at 300–400 °C. TGA-MS spectra indicated that (e.g. C₂H₄, CH₃OH and C₃H₈) were the major components in the evolved gases from the pyrolyzed soil. A maximum amount of Cr(VI) removal (ca. 4 mg g⁻¹ soil) occurred for the 200 °C-carbonized soils, attributed mainly to a significant increase of Cr(VI) reduction by 0.1 M KCl extractable organic carbon (EOC) with abundant carboxylic groups. Nonetheless, the formation of aromatic C upon carbonization of the soil at >400 °C may be responsible for Cr(VI) reduction.
Agid:
866699