稀土元素在土壤和氧化物表面的吸附和解吸研究

ADSORPTION AND DESORPTION OF RARE EARTH ELEMENTS ON SOILS AND SYNTHETIC OXIDES

混合稀土在我国主要类型土壤、铁锰氧化物、高岭石表面的等温吸附符合Freundlich、Temkin和Langmuir吸附方程.最大吸附量(Q_m)的顺序为:δ-MnO_2≥黑土>黑钙土>无定形铁>黄棕壤>红壤>砖红壤>高岭石.决定土壤吸附稀土容量的主要因素是粘土矿物类型,其次是无定型铁含量;土壤对稀土的吸附强度与铁氧化物的专性吸附强度和粘土矿物的交换吸附强度有关.土壤和矿物对混合稀土的专性吸附能力顺序为:δ-MnO_2>无定形铁>黑土、黑钙上>砖红壤>高岭石>红壤、黄棕壤.

The RE (mixed rare earths) isothermal adsorption by soils of the main types in China, synthetic oxides and kaolinite was found following Freund-lich, Temkin, and Langmuir adsorption equations. The maximum RE adsorption capacity (Qm) (mg/g) were, 57.0, 12.7, 7.90, 7.65, 5.13, 1.96,1.62, and 0.90 for δ-MnO2, black soil, chernozem, amorphous iron oxide, yellow brown earth, red earth, laterite, and kaolinite, respectively. The main factors controlling Qm of the soils were the clay type and the content of amorphous iron oxide in the soils. The adsorption strength of RE by the soils was related to that of exchangeable adsorption by clay and that of specific adsorption by oxides in soils. The ability of the soils and the minerals to adsorb RE specifically decreased in the following sequence. δ-MnO2> amorphous iron oxide>black soil, chernozem>laterite>kaolinite>red earth, yellow brown earth.