Cd(II) Sorption on Montmorillonite-Humic acid-Bacteria Composites

Scientific Reports
Huihui DuQiaoyun Huang

Abstract

Soil components (e.g., clays, bacteria and humic substances) are known to produce mineral-organic composites in natural systems. Herein, batch sorption isotherms, isothermal titration calorimetry (ITC), and Cd K-edge EXAFS spectroscopy were applied to investigate the binding characteristics of Cd on montmorillonite(Mont)-humic acid(HA)-bacteria composites. Additive sorption and non-additive Cd(II) sorption behaviour is observed for the binary Mont-bacteria and ternary Mont-HA-bacteria composite, respectively. Specifically, in the ternary composite, the coexistence of HA and bacteria inhibits Cd adsorption, suggesting a "blocking effect" between humic acid and bacterial cells. Large positive entropies (68.1~114.4 J/mol/K), and linear combination fitting of the EXAFS spectra for Cd adsorbed onto Mont-bacteria and Mont-HA-bacteria composites, demonstrate that Cd is mostly bound to bacterial surface functional groups by forming inner-sphere complexes. All our results together support the assertion that there is a degree of site masking in the ternary clay mineral-humic acid-bacteria composite. Because of this, in the ternary composite, Cd preferentially binds to the higher affinity components-i.e., the bacteria.

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Citations

Apr 12, 2017·International Journal of Phytoremediation·Małgorzata Majewska, Jolanta Jaroszuk-Ściseł
Feb 6, 2018·Environmental Science and Pollution Research International·Hanzhi ShiQiaoyun Huang
Aug 1, 2020·Bulletin of Environmental Contamination and Toxicology·Xinyu NongXiaodan Jin
Jun 28, 2018·Bulletin of Environmental Contamination and Toxicology·Shiping ShanLiyang Wu
Jul 20, 2019·Environmental Science and Pollution Research International·Miaomiao XuZemin Wang
Feb 23, 2020·Environmental Science & Technology·Tongxu LiuChengshuai Liu

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Methods Mentioned

BETA
isothermal
X-ray
atomic absorption spectrometry

Software Mentioned

ATHENA
Origin
TAM III
IFEFFIT

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