Desorption Kinetics of Yttrium, Lanthanum, and Cerium from Soils

Abstract

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 (R2 < 0.90). However, excellent agreements were achieved between the experimental data and fits to the latter two kinetic models (R2 > 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.

Metal and nanoparticle occurrence in biosolid-amended soils

“…The measured Ce concentration in soils was (45 ± 4 mg/L) consistent with values previously reported by USGS, namely, an average Ce concentration of 75 mg/kg and a maximum concentration of 300 mg/kg, based on a survey of soil samples from more than 21 US states (Shacklette and Boerngen, 1984). Because water can easily desorb Ce from soils (Wen et al, 2002), the even distribution of Ce in soils could be expected in an area with a mean annual precipitation of 817 mm though other reason could not be excluded (e.g. the historical concentrations of Ce in biosolids might be extremely low).…”

Effect of earthworms (Eisenia fetida) on the fractionation and bioavailability of rare earth elements in nine Chinese soils

“…It is well established that soil pH is a key factor affecting the adsorption-desorption behaviors and hence bioavailability of REEs (Cao et al, 2001;Li et al, 2001;Wen et al, 2002). Therefore, it is important to determine the pH change due to the earthworm activity.…”

A review on the potentiality of Rare Earth Elements to trace pedogenetic processes

“…Usually, REE adsorption increases with increasing pH (Aja, 1998;Coppin, 2002). Desorption of REEs from clay minerals is also pH-dependent (Ran and Liu, 1992;Wen et al, 2002), but restricted and slow (Bonnot- Courtois, 1981;Laufer et al, 1984).…”