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Title: Molecular investigation on the binding of Cd(II) by the binary mixtures of montmorillonite with two bacterial species

Abstract

Bacteria and phyllosilicate commonly coexist in the natural environment, producing various bacteria–clay complexes that are capable of immobilizing heavy metals, such as cadmium, via adsorption. However, the molecular binding mechanisms of heavy metals on these complex aggregates still remain poorly understood. This study investigated Cd adsorption on Gram-positive B. subtilis, Gram-negative P. putida and their binary mixtures with montmorillonite (Mont) using the Cd K-edge x-ray absorption spectroscopy (XAS) and isothermal titration calorimetry (ITC). We observed a lower adsorptive capacity for P. putida than B. subtilis, whereas P. putida–Mont and B. subtilis–Mont mixtures showed nearly identical Cd adsorption behaviors. EXAFS fits and ITC measurements demonstrated more phosphoryl binding of Cd in P. putida. The decreased coordination of C atoms around Cd and the reduced adsorption enthalpies and entropies for the binary mixtures compared to that for individual bacteria suggested that the bidentate Cd-carboxyl complexes in pure bacteria systems were probably transformed into monodentate complexes that acted as ionic bridging structure between bacteria and motmorillonite. This study clarified the binding mechanism of Cd at the bacteria–phyllosilicate interfaces from a molecular and thermodynamic view, which has an environmental significance for predicting the chemical behavior of trace elements in complex mineral–organic systems.

Authors:
; ; ; ; ; ; ; ORCiD logo
Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1378009
Report Number(s):
PNNL-SA-120883
Journal ID: ISSN 0269-7491
DOE Contract Number:  
AC05-76RL01830
Resource Type:
Journal Article
Resource Relation:
Journal Name: Environmental Pollution; Journal Volume: 229; Journal Issue: C
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; 59 BASIC BIOLOGICAL SCIENCES; Cd adsorption

Citation Formats

Du, Huihui, Qu, ChenChen, Liu, Jing, Chen, Wenli, Cai, Peng, Shi, Zhihua, Yu, Xiao-Ying, and Huang, Qiaoyun. Molecular investigation on the binding of Cd(II) by the binary mixtures of montmorillonite with two bacterial species. United States: N. p., 2017. Web. doi:10.1016/j.envpol.2017.07.052.
Du, Huihui, Qu, ChenChen, Liu, Jing, Chen, Wenli, Cai, Peng, Shi, Zhihua, Yu, Xiao-Ying, & Huang, Qiaoyun. Molecular investigation on the binding of Cd(II) by the binary mixtures of montmorillonite with two bacterial species. United States. doi:10.1016/j.envpol.2017.07.052.
Du, Huihui, Qu, ChenChen, Liu, Jing, Chen, Wenli, Cai, Peng, Shi, Zhihua, Yu, Xiao-Ying, and Huang, Qiaoyun. Sun . "Molecular investigation on the binding of Cd(II) by the binary mixtures of montmorillonite with two bacterial species". United States. doi:10.1016/j.envpol.2017.07.052.
@article{osti_1378009,
title = {Molecular investigation on the binding of Cd(II) by the binary mixtures of montmorillonite with two bacterial species},
author = {Du, Huihui and Qu, ChenChen and Liu, Jing and Chen, Wenli and Cai, Peng and Shi, Zhihua and Yu, Xiao-Ying and Huang, Qiaoyun},
abstractNote = {Bacteria and phyllosilicate commonly coexist in the natural environment, producing various bacteria–clay complexes that are capable of immobilizing heavy metals, such as cadmium, via adsorption. However, the molecular binding mechanisms of heavy metals on these complex aggregates still remain poorly understood. This study investigated Cd adsorption on Gram-positive B. subtilis, Gram-negative P. putida and their binary mixtures with montmorillonite (Mont) using the Cd K-edge x-ray absorption spectroscopy (XAS) and isothermal titration calorimetry (ITC). We observed a lower adsorptive capacity for P. putida than B. subtilis, whereas P. putida–Mont and B. subtilis–Mont mixtures showed nearly identical Cd adsorption behaviors. EXAFS fits and ITC measurements demonstrated more phosphoryl binding of Cd in P. putida. The decreased coordination of C atoms around Cd and the reduced adsorption enthalpies and entropies for the binary mixtures compared to that for individual bacteria suggested that the bidentate Cd-carboxyl complexes in pure bacteria systems were probably transformed into monodentate complexes that acted as ionic bridging structure between bacteria and motmorillonite. This study clarified the binding mechanism of Cd at the bacteria–phyllosilicate interfaces from a molecular and thermodynamic view, which has an environmental significance for predicting the chemical behavior of trace elements in complex mineral–organic systems.},
doi = {10.1016/j.envpol.2017.07.052},
journal = {Environmental Pollution},
number = C,
volume = 229,
place = {United States},
year = {Sun Oct 01 00:00:00 EDT 2017},
month = {Sun Oct 01 00:00:00 EDT 2017}
}