Pedosphere 6(3): 251--258, 1996
ISSN 1002-0160/CN 32-1315/P
©1996 Soil Science Society of China
Published by Elsevier B.V. and Science Press
| Adsorption kinetics of Pb2+ and Cu2+ on variable charge soils and minerals: Ⅶ. Kinetics of H+ releasing after Ph2+ adsorption |
| HU Guo-Song |
| Institute of Soil Science, Academia Sinica, P.O.Box 821, Nanjing 210008 (China) |
| ABSTRACT |
| The kinetics of H+ releasing after Pb2+ adsorption was studied by the potentiometric method combined with the acid-base titration curve technique. Results showed that pH of latosol, red soil and kaolinite suspensions dropped sharply, and then decreased gradually. Most of the H+ exchanged, more than 60%, was displaced at the first minute after Pb2+ was added into the suspension. More H+ was released at a higher concentration of Pb2+ added for a given sample and the amount of H+ released decreased in the order of red soil > latosol > kaolinite at a given concentration. The time-dependent data of H+ releasing of latosol, red soil and kaolinite at two concentrations could be fitted best with the second-order equation among the six equations, including second-order equation, two-constant equation, Elovich equation, parabolic diffusion equation, first-order equation and exponential equation. The H+/Pb2+ exchange stoichiometry increased with time, and a stable ratio of H+/Pb2+, being 1.73, 1.92 and 2.01 for kaolinite, latosol and red soil, respectively, was reached 25 minutes later. |
| Key Words: H+ releasing, kinetics, Pb2+ adsorption |
| Citation: Hu, G. S. 1996. Adsorption kinetics of Pb2+ and Cu2+ on variable charge soils and minerals: Ⅶ. Kinetics of H+ releasing after Ph2+ adsorption. Pedosphere. 6(3): 251-258. |
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