Journal
ENVIRONMENTAL POLLUTION
Volume 252, Issue -, Pages 1509-1518Publisher
ELSEVIER SCI LTD
DOI: 10.1016/j.envpol.2019.06.071
Keywords
Extracellular polymeric substance; Montmorillonite; Composite; Cadmium; Adsorption
Categories
Funding
- National Natural Science Foundation of China [51604207, 51674183]
- Strategic Priority Research Program of the Chinese Academy of Sciences [XDA17010502]
- Natural Science Foundation of Hubei Province, China [2018CFB605]
- Fundamental Research Funds for the Central Universities [WUT:183108001, 173208001, 193208007]
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Extracellular polymeric substance (EPS)-mineral associations occur naturally in soil and sediments, and they might play crucial roles in heavy metals immobilization. In this study, EPS-montmorillonite composites with different weight ratios were characterized and investigated for their Cd(II) sorption behavior. The results showed that the EPS chains can intercalate into montmorillonite layers by hydrogen bonding connection and chemical reaction between C=O, C-N and COO- groups with interlayer cations of montmorillonite, therefore promoting delamination of montmorillonite, especially under a lower weight ratio. An enhancement adsorption of heavy metals was obtained with the composites at lower weight ratios of 1:50 and 0.5:50, whereas composites with higher weight ratio of 5:50 presented a reduced adsorption ability, demonstrating that adsorption of Cd(II) onto the EPS-montmorillonite composites was weight ratio dependent. AFM, CLSM, FT-IR and XPS analysis illustrated that the enhancement of sorption under low weight ratio can be attributed to the release of surface active sites of EPS because of reduced aggregation, the increase of negative surface charges when EPS and montmorillonite were interacted and additional bridging of cadmium ions between EPS and montmorillonite. These findings extend the knowledge into the mobility and fate of Cd(II) in organic matter rich soils and sediments. (C) 2019 Elsevier Ltd. All rights reserved.
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