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
摘要
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 <italic>T</italic> = 25 ± 2℃ and in 0.01 mol/L NaClO<sub>4</sub> 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 Å 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.