稀土元素与腐殖酸在水合氧化铁体系中的吸附机制

实验考察稀土元素(La3 、Ce3 、Ho3 、Yb3 )在水合氧化铁表面的吸附动力学过程,对比研究腐殖酸对吸附机制的影响.当腐殖酸与稀土元素共存时,腐殖酸通过化学吸附优先占据氧化铁表面的吸附点位,颗粒物表面特性因覆盖有机膜而得到修饰.初期的动力学过程主要表现为腐殖酸的竞争吸附,随后转变为吸附态腐殖酸对稀土元素的表面结合.轻稀土因较强的结合能力而比重稀土易于被吸附去除,这与天然水体中发生的稀土元素分异现象保持一致.

Adsorption mechanism of rare earth elements and humic acids in the system of iron oxyhydroxide

Kinetics of rare earth elements(La~(3+),Ce~(3+),Ho~(3+),Yb~(3+)) adsorption to the iron oxyhydroxide were investigated,and the effects of humic acid on adsorption mechanism were revealed.Coexisting humic acid with rare earth elements(REEs),the surface sites of iron oxyhydroxide might be occupied preeminently by the humic acid through the chemical adsorption,and the characteristics of the solids are decorated by covering the organic membrane.The adsorption kinetics of REEs initially shows the competitive adsorption with humic acid,and then is the surface binding with the adsorbed humic acid.The LREEs tend to be adsorbed on the solids and removed from the liquid due to their stronger binding ability with humic acid than the HREEs,which is consistent with the fractionation of the REEs taking place in the natural waters.