稀土元素在高岭石表面的吸附机制研究

Study of Adsorption Mechanism of Rare Earth Elements on Kaolinite Surface

通过批吸附实验,揭示不同pH(3.0~8.0)下高岭石对REE^(3+)的吸附过程,系统研究了吸附过程中的Yb/La及Tb/La分异机制并量化其分异程度。吸附实验结果表明,高岭石矿物表面对La^(3+)、Tb^(3+)和Yb^(3+)的吸附量随pH升高而逐渐增加,在pH为8时达到最大吸附量,吸附效果最佳。同时,吸附过程中,稀土离子倾向于形成稳定的内层配合物,且该过程明显富集中重稀土元素。这一结果为风化壳离子吸附型稀土矿的成矿机理探讨提供了新思路。

In the present work,batch adsorption experiments were employed to study the adsorption process ^(3+)of REE on the edge surface of kaolinite at different pH(3.0—8.0).The partitioning mechanism of Yb/La and Tb/La during surface adsorption,as well as the degree of partitioning were systematically studied.It aims tofind out the control factors of the partitioning,finally facilitating discussions of the mineralization mechanism of ion-absorbed rare-earth ore deposits.Experimental results show that the adsorption capacity of La^(3+),^(3+)^(3+)Tb and Yb on the surface of kaolinite gradually increases with the increase of pH,and the maximum adsorption capacity is reached at pH 8,and the adsorption effect is the best.Meanwhile,during adsorption,REE^(3+)tend to form stable inner-sphere complexes and MREE and HREE were found to be enriched in this process.These observations provide a new perspective for genesis of ion adsorption type REE deposits in the weathering crusts.