期刊
SCIENCE OF THE TOTAL ENVIRONMENT
卷 651, 期 -, 页码 2975-2984出版社
ELSEVIER SCIENCE BV
DOI: 10.1016/j.scitotenv.2018.10.165
关键词
Humic acid; Humin; Hexavalent chromium; Two-dimensional correlation spectroscopy; Correlation analysis
资金
- National Natural Science Foundation of China [41672239]
- National Key R&D Program of China [2017YFF0205804]
- National Science and Technology Major Project [2016ZX05040-002-003]
- China Geological Survey [1212011121173]
Different soil humus fractions are structurally distinct from each other molecularly, however, the relationship between their microscopic molecular structures and the macroscopic reduction of Cr(VI) is still unknown, especially for the humin fraction. In this study, different humus fractions (HA, humic acid; HMi, humin linked to iron oxides; HMc, humin linked to clay; and HMr, humin residue) were sequentially extracted from a typical black soil and well characterized. It was found that HA, HMi and HMc were the same type of humus with similar molecular structures, while HMr was structurally different from the other fractions with a high cellulose content. The removal rate of Cr(VI) in solution decreased with progressive humus fractionation, namely, HA > HMi > HMc > HMr. Based on the two-dimensional correlation spectroscopic analysis (2DCOS) of the FTIR data, the changing functional groups of all humus fractions during reacting with Cr(VI) followed a similar order: carboxyl > phenol > hydroxyl > methyl > methylene.According to the correla tion analysis, Cr(VI) reduction rates by different humus fractions were mainly determined by the content of phenol (R-2 = 0.99) instead of carboxyl (R-2 = 0.28). Except for HMr, the Cr(VI) reduction rates of different humus fractions were also positively correlated with surface and bulk polarity (R-2 = 0.98 and 0.99) but not with aromaticity or aliphatidty (R-2 = 0.21). (C) 2018 Elsevier B.V. All rights reserved.
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