title: Influence of bacterial extracellular polymeric substances on the sorption of Zn on γ-alumina: A combination of FTIR and EXAFS studies.
abstract: 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-1EPS, 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.
authors.affiliation: 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.
authors.forename: Cheng-Cheng
authors.initials: CC
authors.lastname: Li
authors.affiliation: Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, PR China.
authors.forename: Yu-Jun
authors.initials: YJ
authors.lastname: Wang
authors.affiliation: Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, PR China.
authors.forename: Huan
authors.initials: H
authors.lastname: Du
authors.affiliation: State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, PR China.
authors.forename: Peng
authors.initials: P
authors.lastname: Cai
authors.affiliation: National Institute of Public Health and the Environment, Center for Safety of Substances and Products, 3720 BA, Bilthoven, The Netherlands; Institute of Environmental Sciences, Leiden University, Leiden, The Netherlands.
authors.forename: Willie J G M
authors.initials: WJGM
authors.lastname: Peijnenburg
authors.affiliation: Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, PR China. Electronic address: dmzhou@issas.ac.cn.
authors.forename: Dong-Mei
authors.initials: DM
authors.lastname: Zhou
mesh_terms: D000327:Adsorption; D000537:Aluminum Oxide / Q000737:chemistry*; D001412:Bacillus subtilis / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D006878:Hydroxides; D011108:Polymers / Q000737:chemistry; D016958:Pseudomonas putida / Q000737:chemistry; D017550:Spectroscopy, Fourier Transform Infrared; D056928:X-Ray Absorption Spectroscopy; D015032:Zinc / Q000737:chemistry*
chemical_list: D006878:Hydroxides; D011108:Polymers; C031356:hydroxide ion; D015032:Zinc; D000537:Aluminum Oxide
keywords: EPS; EXAFS; FTIR; Sorption mechanism; Zn