Desorption Kinetics of Yttrium, Lanthanum, and Cerium from Soils
2002
Wen, Bei | Shan, Xiao-quan | Lin, Jin-Ming | Tang, Gui-gang | Bai, Nai-bin | Yuan, Dong-an
Study on desorption kinetics of Y, La, and Ce from soils is of importance because it relates to the bioavailability and potential toxicity of rare-earth elements. In the present study, a column-flow method and three models (first-order, two site first-order, and log-normal distribution first-order kinetics models) were used to describe the desorption kinetics of Y, La, and Ce from four Chinese soils with different physicochemical properties. A high desorption percentage of Y (87.1–96.6%), La (89.9–98.5%), and Ce (57.6–96.4%) from Yingtan soil was attributed to the low soil pH 5.43 and low organic matter of 1.53%. In contrast, a low percentage of Y (27.5–45.7%), La (27.6–53.6%), and Ce (1.09–50.8%) sorbed by Beijing, Tongjiang, and Haerbin soils desorbed probably because of the higher soil pH values of 8.24, 7.16, 7.23, and increased organic matter (36.4%) in Haerbin soil. The results also suggest that the first-order kinetics model did not offer an acceptable description of the data (R ² < 0.90). However, excellent agreements were achieved between the experimental data and fits to the latter two kinetic models (R ² > 0.99). The parameters derived from the kinetic equations indicated that increasing the initial sorption period from 1 to 20 wk could lead to a strong binding of rare-earth elements, resulting in slower desorption.
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