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高等学校化学研究 ›› 2012, Vol. 28 ›› Issue (4): 624-630.

• Articles • 上一篇    下一篇

Binding of Pyrene to Different Molecular Weight Fractions of Dissolved Organic Matter: Effects of Chemical Composition and Steric Conformation

WU Ji-zhou1, SUN Hong-wen1, WANG Cui-ping1, LI Yong-hong 2   

  1. 1. Key Laboratory of Pollution Processes and Environmental Criteria, Ministry of Education, College of Environmental Science and Engineering, Nankai University, Tianjin 300071, P. R. China;
    2. State Key Laboratory of Elemento-Organic Chemistry, Research Institute of Elemento-Organic Chemistry, Nankai University, Tianjin 300071, P. R. China
  • 收稿日期:2011-09-22 修回日期:2012-03-27 出版日期:2012-07-25 发布日期:2012-07-25
  • 通讯作者: SUN Hong-wen E-mail:sunhongwen@nankai.edu.cn
  • 基金资助:

    Supported by the National Natural Science Foundation of China(Nos.20737002, 41073087).

Binding of Pyrene to Different Molecular Weight Fractions of Dissolved Organic Matter: Effects of Chemical Composition and Steric Conformation

WU Ji-zhou1, SUN Hong-wen1, WANG Cui-ping1, LI Yong-hong 2   

  1. 1. Key Laboratory of Pollution Processes and Environmental Criteria, Ministry of Education, College of Environmental Science and Engineering, Nankai University, Tianjin 300071, P. R. China;
    2. State Key Laboratory of Elemento-Organic Chemistry, Research Institute of Elemento-Organic Chemistry, Nankai University, Tianjin 300071, P. R. China
  • Received:2011-09-22 Revised:2012-03-27 Online:2012-07-25 Published:2012-07-25
  • Supported by:

    Supported by the National Natural Science Foundation of China(Nos.20737002, 41073087).

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被引次数

8

摘要： The binding constant(KDOM) of pyrene onto different molecular weight(Mw) fractions of a dissolved organic matter(DOM) extract from an estuarine sediment was measured via a fluorescence quenching method, and the possible binding mechanisms were discussed. The influence of water chemical parameters on pyrene binding was studied to elucidate the effects of DOM steric conformation. DOM fraction with larger Mw(>14000) showed a greater KDOM(2.02×105) than that with smaller Mw did, and the KDOMs were 1.16×105 and 1.13×105 for the fractions with Mw of 1000-14000 and <1000, respectively. The KDOMs of different Mw DOM fractions were correlated positively with the atomic ratio of C/H and absorbance at 280 nm; while a negative correlation existed between KDOM and (O+C)/N (atomic ratio), and KDOM and O-containing groups. These correlations indicate the positive influence of aromatic structure and the negative effect of polarity on DOM binding capacity. Infrared spectroscopy revealed that specific interactions existed between pyrene and the DOM fraction with larger MW besides hydrophobic partition, i.e., NH-π interaction in DOM moiety(1000-14000) and π-π electron donor acceptor(EDA) forces in DOM moiety (>14000). KDOM varied in a complex pattern with increasing cation concentration and pH, which could be explained by the change in DOM steric conformation. Formed aggregates favored the lipophilic partition of pyrene. However, the accessibility to some interior binding sites became low when the aggregate was too large, leading to a reduced KDOM.

关键词: Dissolved organic matter, Conformation, Water chemistry, Pyrene, Binding constant

Abstract: The binding constant(KDOM) of pyrene onto different molecular weight(Mw) fractions of a dissolved organic matter(DOM) extract from an estuarine sediment was measured via a fluorescence quenching method, and the possible binding mechanisms were discussed. The influence of water chemical parameters on pyrene binding was studied to elucidate the effects of DOM steric conformation. DOM fraction with larger Mw(>14000) showed a greater KDOM(2.02×105) than that with smaller Mw did, and the KDOMs were 1.16×105 and 1.13×105 for the fractions with Mw of 1000-14000 and <1000, respectively. The KDOMs of different Mw DOM fractions were correlated positively with the atomic ratio of C/H and absorbance at 280 nm; while a negative correlation existed between KDOM and (O+C)/N (atomic ratio), and KDOM and O-containing groups. These correlations indicate the positive influence of aromatic structure and the negative effect of polarity on DOM binding capacity. Infrared spectroscopy revealed that specific interactions existed between pyrene and the DOM fraction with larger MW besides hydrophobic partition, i.e., NH-π interaction in DOM moiety(1000-14000) and π-π electron donor acceptor(EDA) forces in DOM moiety (>14000). KDOM varied in a complex pattern with increasing cation concentration and pH, which could be explained by the change in DOM steric conformation. Formed aggregates favored the lipophilic partition of pyrene. However, the accessibility to some interior binding sites became low when the aggregate was too large, leading to a reduced KDOM.

Key words: Dissolved organic matter, Conformation, Water chemistry, Pyrene, Binding constant