Pedosphere 9(3): 243--250, 1999
ISSN 1002-0160/CN 32-1315/P
©1999 Soil Science Society of China
Published by Elsevier B.V. and Science Press
| Temperature effect on boron adsorption-desorption kinetics in soils |
| ZHU Duan-Wei, SHI Lei and LIU Wu-Ding |
| Laboratory of Trace Elements, Huazhong Agriculturul University, Wuhan 430070 (China) |
| ABSTRACT |
| The effect of temperature on the properties of boron adsorption-desorption in brown-red soil, yellow-brown soil and calcareous alluvial soil of Hubei Province was investigated with the mobile displacement technique. The experimental data of B adsorption-desorption amounts and reaction time at 25 and 40 ℃ were fitted by the zero-order, first-order and parabolic diffusion kinetic equations. The adsorption process was in conformity with the parabolic diffusion law at both the temperatures, and the values of rate constant of the parabolic diffusion equation in B adsorption were 0.138, 0.124 and 0.105 mg kg-1 min-1/2 at 25 ℃, and 0.147, 0.146 and 0.135 mg kg-1 min-1/2 at 40 ℃ for the brown-red soil, yellow-brown soil, and calcareous alluvial soil, respectively. The relationship between amount of B desorption and reaction time could be well described by the first-order kinetic equation, and the corresponding values of rate constant were 0.042 2, 0.056 3 and 0.038 4 min-1 at 25 ℃, and 0.040 8, 0.042 3 and 0.040 1 min-1 at 40 ℃ for the brown-red soil, the yellow-brown soil and the calcareous alluvial soil, respectively. Therefore, the desorption process of B might be related to the amount of B adsorbed in soil. The higher the temperature, the lower the amount of B adsorption for the same soil in the same reaction time. The values of the apparent activation energy of B adsorption in the three soils calculated with the rate constants of parabolic diffusion equation were 3.27, 8.44 and 12.99 kJ mol-1, respectively, based on the experimental data of B adsorption amounts and reaction time at 25 and 40 ℃. |
| Key Words: activation energy, adsorption-desorption, hinetics, soil boron, temperature |
| Citation: Zhu, D. W., Shi, L. and Liu, W. D. 1999. Temperature effect on boron adsorption-desorption kinetics in soils. Pedosphere. 9(3): 243-250. |
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