Pedosphere 4(4): 289--296, 1994
ISSN 1002-0160/CN 32-1315/P
©1994 Soil Science Society of China
Published by Elsevier B.V. and Science Press
| Determination of formation constants of Co2+, Ni2+, Cu2+ and Zn2+ complexes with humic and fulvic acids by potentiometric titration method |
| DU Jin-Zhou1, JING Qi1, CHU Tai-Wei1, DAI Xiong-Xin1, TAO Zu-Yi1 and LU Chang-Qing2 |
1 Department of Modern Physics, Lanzhou University, Lanzhou 730000 (China);
2 Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008 (China) |
| ABSTRACT |
| The formation constants of Co2+, Ni2+, Cu2+ and Zn2+ complexes with humic acid (HA) and fulvic acid (FA) in red soil were determined by the potentiometric titration method. The constants as a function of composition of the complexation solutions were obtained by two graphical approaches respectively. The formation constants decreased with increasing concentration of metal in the solution. The results provide unambiguous evidence for the heterogeneity of the function groups of humic substances. The formation constants of FA were much smaller than those of HA, and the formation constants of Cu2+ were much greater than those of Co2+, Ni2+ and Zn2+. The potentiometric titration method for determining formation constants are also discussed in the article. |
| Key Words: formation constants of complexes, humic and fulvic acids, potentiometric titration, red soil |
| Citation: Du, J. Z., Jing, Q., Chu, T. W., Dai, X. X., Tao, Z. Y. and Lu, C. Q. 1994. Determination of formation constants of Co2+, Ni2+, Cu2+ and Zn2+ complexes with humic and fulvic acids by potentiometric titration method. Pedosphere. 4(4): 289-296. |
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