静态法和X射线吸收精细结构光谱技术研究腐殖酸对Eu(III)在高庙子膨润土上的吸附影响

膨润土由于其高吸附性和低渗透性而受到广泛的研究. 在本文中, 利用XRD、FTIR和酸碱滴定对我国内蒙古高庙子膨润土进行了详细的表征和分析. 用静态法研究在温度为25± 2 ℃和0.01 mol/L NaClO4溶液中, pH值、腐殖酸、接触时间和Eu(III)初始浓度对Eu(III)在钠基膨润土上的吸附影响. 研究结果表明Eu(III)的吸附受pH值影响明显. 在低pH值条件下, 腐殖酸对Eu(III)的吸附影响微弱, 而在高pH值条件下腐殖酸降低Eu(III)的吸附. X射线吸收精细结构光谱(XAFS)技术对吸附在膨润土上的Eu(III)局域微观结构研究结果表明, 在pH为4.15条件下, Eu在膨润土上与其周围的氧原子间的距离大约为2.39 Å. 本文中的研究结果对于评估其他三价镧系和锕系元素在作为填充材料的膨润土上的吸附和迁移具有重要的意义.

Sorption of Eu（Ⅲ） on GMZ bentonite in the absence/presence of humic acid studied by batch and XAFS techniques

Bentonite has been studied extensively because of its strong sorption ability and low permeability.In this paper,the Na-bentonite from Gaomiaozi county （China） has been characterized by XRD,FTIR and acid-base titration in detail.The sorption of Eu（Ⅲ） on Na-bentonite in the absence/presence of humic acid （HA） was studied at T=25 ± 2 ℃ and in 0.01 mol/L NaClO4 solutions.The effects of pH,HA,contact time and initial Eu（Ⅲ） concentrations were also investigated.The results indicate that the sorption of Eu（III） on Na-bentonite was strongly dependent on pH values.The presence of HA had little effect on Eu（III） sorption at low pH values,but decreased Eu（Ⅲ） sorption at high pH values.X-ray absorption fine structure spectroscopy （XAFS） was applied to characterize the local structural environment of the adsorbed Eu（III） on bare Na-bentonite and HA-bentonite hybrids,and the results indicate that Eu（Ⅲ） was bound to O atoms at a distance of about 2.39 at pH 4.15.The results are important to the evaluation of the sorption and migration of other trivalent lanthanides and actinides in bentonite as backfill materials.