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

  • [设施]:上海光源
  • [期刊/会议名称]:Environmental Pollution
  • [摘要]:Bacteriaephyllosilicate complexes are commonly found in natural environments and are capable of immobilizing trace metals. However, the molecular binding mechanisms of heavy metals to these complex aggregates still remain poorly understood. This study investigated Cd adsorption on Grampositive Bacillus subtilis, Gram-negative Pseudomonas putida and their binary mixtures with montmorillonite using surface complexation model, Cd K-edge extended X-ray absorption fine structure (EXAFS) spectroscopy and isothermal titration calorimetry (ITC). We have shown that larger amounts of Cd are adsorbed by B. subtilis than by P. putida at pH<~6, and Cd sorption that binding to phosphate groups plays a more important role in P. putida than in B. subtilis. This remind us that we should consider the microbe species when predict the biochemical behavior of trace metals in microbe-bearing environments. The observed Cd adsorption on the binary bacteriaeclay composites was more than that predicted based on the component additivity approach. When taking bacteriaeclay (1:1 mass ratio) as a representative example, an approximately 68%:32% metal distribution between the bacterial and mineral fraction was found. Both the EXAFS and ITC fits showed that the binding stoichiometry for Cd-carboxyl/phosphate was smaller in the binary mixtures than that in pure bacteria. We proposed that the significant deviations were possibly due to the physical-chemical interaction between the composite fractions that might reduce the agglomeration of the clay grains, increase the negative surface charges, and provide additional bridging of metals ions between bacterial cells and clays.
  • [发表日期]:2017
  • [第一作者]:Huihui Du, ChenChen Qu
  • [第一作者单位]:华中农业大学资源与环境学院
  • [通讯作者]:Qiaoyun Huang
  • [通讯作者单位]:华中农业大学资源与环境学院
  • [论文类型]:0
  • [期刊分类]:SCI2区
  • [学科分类]:环境科学_生态学
  • [影响因子]:5.0
  • [关键词]:Bacteria Montmorillonite Mixture Cd Adsorption
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