Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, PR China; University of Chinese Academy of Sciences, Beijing 100049, PR China; Department of Environmental Science and Engineering, College of Environment and Resources, Xiangtan University, Xiangtan 411105, PR China.
Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, PR China.
Environ Pollut. 2017 Jan;220(Pt B):997-1004. doi: 10.1016/j.envpol.2016.11.048. Epub 2016 Nov 19.
Extracellular polymeric substances (EPS) isolated from bacteria, are abound of functional groups which can react with metals and consequently influence the immobilization of metals. In this study, we combined with Zn K-edge Extended X-ray Absorption Fine Structure (EXAFS), Fourier Transform Infrared (FTIR) spectroscopy, and High-Resolution Transmission Electron Microscopy (HRTEM) techniques to study the effects of EPS isolated from Bacillus subtilis and Pseudomonas putida on Zn sorption on γ-alumina. The results revealed that Zn sorption on aluminum oxide was pH-dependent and significantly influenced by bacterial EPS. At pH 7.5, Zn sorbed on γ-alumina was in the form of Zn-Al layered doubled hydroxide (LDH) precipitates, whereas at pH 5.5, Zn sorbed on γ-alumina was as a Zn-Al bidentate mononuclear surface complex. The amount of sorbed Zn at pH 7.5 was 1.3-3.7 times higher than that at pH 5.5. However, in the presence of 2 g L EPS, regardless of pH conditions and EPS source, Zn + EPS + γ-alumina ternary complex was formed on the surface of γ-alumina, which resulted in decreased Zn sorption (reduced by 8.4-67.8%) at pH 7.5 and enhanced Zn sorption (increased by 10.0-124.7%) at pH 5.5. The FTIR and EXAFS spectra demonstrated that both the carboxyl and phosphoryl moieties of EPS were crucial in this process. These findings highlight EPS effects on Zn interacts with γ-alumina.
从细菌中分离出的胞外聚合物（EPS）含有丰富的功能基团，可与金属发生反应，从而影响金属的固定。在这项研究中，我们结合 Zn K 边扩展 X 射线吸收精细结构（EXAFS）、傅里叶变换红外（FTIR）光谱和高分辨率透射电子显微镜（HRTEM）技术，研究了枯草芽孢杆菌和铜绿假单胞菌 EPS 对γ-氧化铝上 Zn 吸附的影响。结果表明，细菌 EPS 对 Zn 在氧化铝上的吸附具有显著影响，且与 pH 值有关。在 pH 值为 7.5 时，Zn 主要以 Zn-Al 层状双氢氧化物（LDH）沉淀的形式吸附在氧化铝上，而在 pH 值为 5.5 时，Zn 主要以 Zn-Al 双齿单核表面配合物的形式吸附在氧化铝上。在 pH 值为 7.5 时，吸附的 Zn 量比 pH 值为 5.5 时高 1.3-3.7 倍。然而，在 2 g/L EPS 的存在下，无论 pH 值条件和 EPS 来源如何，在γ-氧化铝表面都会形成 Zn+EPS+γ-alumina 三元配合物，导致在 pH 值为 7.5 时 Zn 吸附减少（减少 8.4-67.8%），而在 pH 值为 5.5 时 Zn 吸附增加（增加 10.0-124.7%）。FTIR 和 EXAFS 光谱表明，EPS 的羧基和磷酸基在这个过程中都很重要。这些发现强调了 EPS 对 Zn 与γ-氧化铝相互作用的影响。
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