Acta Chim. Sinica ›› 2018, Vol. 76 ›› Issue (7): 543-548.DOI: 10.6023/A18030111 Previous Articles     Next Articles

Article

希瓦氏菌MR-1影响玻碳表面电沉积Cd的机理

林伟芬, 陈念嘉, 游乐星, 周顺桂   

  1. 福建农林大学资源与环境学院 福建省土壤环境健康与调控重点实验室 福州 350002
  • 出版日期:2018-07-15 发布日期:2018-06-11
  • 通讯作者: 游乐星,E-mail:lxyou@fafu.edu.cn E-mail:lxyou@fafu.edu.cn
  • 基金资助:

    项目受国家自然科学基金青年科学基金(No.21603031)和福建省自然科学基金(No.2018J01668)资助.

Shewanella oneidensis MR-1 Affects the Mechanism of Cd Electrodeposition on Glassy Carbon Electrode

Lin Weifen, Chen Nianjia, You Lexing, Zhou Shungui   

  1. Fujian Provincial Key Laboratory of Soil Environmental Health and Regulation, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou 350002
  • Online:2018-07-15 Published:2018-06-11
  • Contact: 10.6023/A18030111 E-mail:lxyou@fafu.edu.cn
  • Supported by:

    Project supported by the National Natural Science Foundation of China (No. 21603031) and the Natural Science Foundation of Fujian Province (No. 2018J01668).

The geochemical cycle of heavy metal ion driven by microbes is widespread in nature. Previous studies are focused on the removal efficiency in the treatment of Cd in the bioelectrochemical systems; however, little is reported regarding the reduction mechanism of Cd on the electrode surface in the neutral physiological environment. In this work, we investigated the microbiological influence of Shewanella oneidensis MR-1 wild type and its mutant △omcA-△mtrc for Cd electrodeposition on a glassy carbon electrode (GCE) surface by using cyclic voltammetric (CV) and chronoamperometric methods. The CVs and I-t curves were carried out in a three-electrode system in the present of MR-1 cells (the value of optical density at 600 nm was 0.5) under nitrogen atmosphere. Much results were found in the present of MR-1 wild type:(1) the reducing peak potentials for Cd electrodeposition obviously negative shifted from CVs; (2) when the scan rate was comparatively slow (20 mV·s-1 vs. saturated calomel electrode), the Cd electrodeposition process contained two steps in the second scan in CVs which were Cd(Ⅱ)-Cd(I)-Cd; (3) the average diffusion coefficient of Cd(Ⅱ) from bulk solution to GCE surface (0.93×10-6 cm·s-1), calculated from I-t curves, was slightly slower than that without MR-1 wild type (1.1×10-6 cm·s-1); (4) the progressive nucleation mechanism for Cd electrodeposition changed into an instantaneous three-dimensional nucleation by compared with their actual nucleation curves. Once the Cd electrodeposition process was performed in the solution with △omcA-△mtrc mutant, the diffusion of Cd(Ⅱ) from bulk solution to GCE surface (the average diffusion coefficient was 0.84×10-6 cm·s-1) changed much slower than before; nonetheless, the Cd electrodeposition was also consistent with the instantaneous three-dimensional nucleation. On the other hand, inhomogeneous Cd particles were observed on GCE surfaces at different stepping potentials from scanning electron microscopy (SEM) images. In contrast, the homogeneous Cd particles were found in the present of MR-1 wild type and △omcA-△mtrc mutant when the reduction potentials were higher than -0.9 V. These SEM results regarding the surface morphology of electrodeposited Cd particles also well agreed with three-dimensional nucleation mechanisms.

Key words: Shewanella oneidensis MR-1, electrodeposition, Cd, nucleation mechanism