| 二价锰离子对柠檬酸还原六价铬的催化作用 |
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| 作者姓名： | LI Chen LAN Ye-Qing DENG Bao-Lin |
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| 作者单位： | College of Science, Nanjing Agricultural University, Nanjing 210095 (China). E-mail: lanyq102@njau.edu.cn;College of Science, Nanjing Agricultural University, Nanjing 210095 (China). E-mail: lanyq102@njau.edu.cn;College of Science, Nanjing Agricultural University, Nanjing 210095 (China). E-mail: lanyq102@njau.edu.cn |
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| 摘 要： | The catalysis of manganese(Ⅱ) (Mn2+) on chromium(Ⅵ) (Cr6+) reduction by citrate was studied through batch experiments with the concentration of citrate greatly in excess of Cr6+ at 25℃ and in pH ranges of 4.0 to 5.0. Results showed that at pH 4.5 within 22 h direct reduction of Cr6+ by citrate was not observed, but for the same time when Mn2+ (50 to 200μmol L-1) was added, nearly all Cr6+ was reduced, with the higher initial Mn2+ concentration having faster Cr6+ reduction. In the initial stage of the reaction, the Cr6+ reduction could be described with a pseudo-first-order kinetics equation. In the later stage of the reaction, plots of lnc(Cr6+) versus t, where c(Cr6+) is the Cr6+ concentration in the reaction and t is the reaction time, deviated from the initial linear trend. The deviations suggested that the pseudo-first-order kinetics did not apply to the whole experimental period and that some reaction intermediates could have greatly accelerated Cr6+ reduction by citrate. The catalysis of the intermediates increased with the reaction time and gradually reached stability. Then, the plot of lnc(Cr6+) versus t in the presence of Mn2+ was linear again, with the rate constant increasing by 102 times compared with the absence of Mn2+. Complexation between Mn2+ and citrate was likely a prerequisite for the catalysis of Mn2+ on the reaction. Additional experiments showed that introducing ethylenediaminetetraacetic acid (EDTA) into the reaction system strongly suppressed the catalysis of Mn2+.
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| 关 键 词： | chromium(Ⅵ) manganese(Ⅱ) |
Catalysis of Manganese(Ⅱ) on Chromium(Ⅵ) Reduction by Citrate |
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| LI Chen,LAN Ye-Qing,DENG Bao-Lin.Catalysis of Manganese(Ⅱ) on Chromium(Ⅵ) Reduction by Citrate[J].Pedosphere,2007,17(3):318-323. |
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| Authors: | LI Chen LAN Ye-Qing and DENG Bao-Lin |
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| Institution: | College of Science, Nanjing Agricultural University, Nanjing 210095 (China). E-mail: lanyq102@njau.edu.cn;College of Science, Nanjing Agricultural University, Nanjing 210095 (China). E-mail: lanyq102@njau.edu.cn;Department of Civil and Environmental Engineering, University of Missouri-Columbia, Columbia MO 65211(USA) |
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| Abstract: | |
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| Keywords: | catalysis citrate reduction |
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