skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

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. 2017. "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 = 2017,
month =
}
  • Initial yields of excited species resulting from electron degradation in Ar+H/sub 2/ mixtures have been calculated using the Fowler equation. Following up the previous study of yields of ions by Eggarter (J. Chem. Physl 84, 6123 (1986)) and by Inokuti and Eggarter (J. Chem. Phys. 86, 3870 (1987)), the present work treats initial yields of excited species over the entire range of the composition of Ar+H/sub 2/ mixtures. The variation of the yield with the composition depends on the kind of excited species. The most noteworthy of the results obtained concerns the Ar metastable-state yield, which shows peculiar behavior whenmore » a small amount of H/sub 2/ is introduced in the media.« less
  • The authors report a new approach to novel liquid crystalline moieties having a greatly enhanced mesomorphic range through the formation of intermolecular hydrogen bonds between two dissimilar mesogens. In liquid crystals, mesomorphicity results from a proper combination of the shape of a molecule and the magnitude and direction of molecular interactions between molecules. While the importance of dipole-dipole interactions in the formation of mesophases has long been established, we have hypothesized that the occurrence of intermolecular hydrogen bonding should have great potential for ordering thermotropic liquid crystals because H-bonding is much stronger than dipole-dipole interactions.
  • Using a method originally proposed for describing a continuum-space polymer fluid, a new expression for the Helmholtz energy of mixing is proposed for a binary lattice mixture. Molecular size asymmetry and nonrandomness due to segment-segment interactions are taken into account. An expression proposed by Yan, Liu and Hu for a binary lattice mixture of monomers, based on the Ising model, is used as a reference system. Calculated critical constants and liquid-liquid coexistence curves are in good agreement with Monte Carlo simulations for lattice mixtures with modest size asymmetry. Because lattice spacing rises with increasing temperature, comparison of calculated binary liquid-liquidmore » equilibria with experiment requires that calculations take into account that the interchange energy falls as temperature rises. While the new expression for the Helmholtz energy of mixing provides much improvement over the Flory-Huggins equation, calculated liquid-liquid equilibria for three binary systems are similar to those from Guggenheim's quasi-chemical theory.« less
  • No abstract prepared.