Formation mechanism of organic-mineral complexes simulated by subcritical water treatment method
WANG Fei, HE Jiang-tao, HE Bao-nan
Key Laboratory of Water Resources and Environmental Engineering, School of Water Resources and Environment, China University of Geosciences, Beijing 100083, China
Humification of organic matter and formation of organic-mineral complexes were simulated with subcritical water treatment method. A series of samples containing commercial humic acid, kaolin, and organic-mineral complexes were prepared under designed temperature, pressure and reaction time, respectively, in a high-temperature and high-pressure reaction kettle. Changing characteristic and mechanism of these samples under different conditions were investigated by means of specific surface area analysis (SSA), Fourier infrared spectrum (FTIR), particular wavelength absorbance ratio (E4/E6), X-ray diffraction (XRD) and 13C nuclear magnetic resonance (13C-NMR). The results showed that SSA, molecular weight, and degree of aromatization (from 59.52% to 70.90%) of humic acids increased significantly with increasing temperature and pressure. This was caused by the cyclization and polymerization of free carboxyl and chain hydrocarbon in humic acid, which led to a more complicated structure and an improvement of chemical stability of humic acids. Increasing temperature and pressure resulted in dehydration and a complete and orderly structure of kaolin. There were several interactions involved in the formation of organic-mineral complexes. At first, aromatic components of humic acid intercalated into kaolin and caused a relatively dense inner structure. Then, the cyclized and polymerized free carboxyl, alkanes and chain structures patched loosely on the kaolin and formed the outer space. The change trend of humic acid, kaolin and their complexes in the experiments was consistent with the direction of mineralization and humification of these substances in nature.
王菲, 何江涛, 何宝南. 亚临界水处理模拟有机-矿质复合体形成机制探讨[J]. 中国环境科学, 2016, 36(8): 2495-2504.
WANG Fei, HE Jiang-tao, HE Bao-nan. Formation mechanism of organic-mineral complexes simulated by subcritical water treatment method. CHINA ENVIRONMENTAL SCIENCECE, 2016, 36(8): 2495-2504.
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