Np(Ⅴ)在黄土及其固相组分上的吸附与解吸——相对贡献、滞后系数、溶液中腐殖酸和碳酸盐的影响

Sorption and Desorption of Neptunium (Ⅴ) on Loess and Its Solid Components: Relative Contribution and Hysteresis? Effects of Fulvic Acid and Carbonate in Solution

本文用批实验法和选择性提取法研究了有机质 ( OM)和 Ca CO3 对 Np( )在黄土上的吸附影响 ,测定了在未处理黄土和去除 Ca CO3 、去除 OM、去除 Ca CO3 和 OM三种处理黄土上 Np( )的吸附和解吸等温线 ,并用 Fre-undlich方程进行了分析。结果表明 ,Ca CO3 对 Np( )在黄土上的吸附 /解吸滞后有一定影响 ,对 Np( )的吸附有负贡献 ;OM对 Np( )在黄土上的吸附 /解吸滞后没有影响 ,且对 Np( )的吸附影响很小 ;溶液中的腐殖酸 FA或CO3 2 -对 Np( )的吸附有明显的正作用 ;Np( )在黄土上的吸附主要受粘土矿物成分的影响 ;Np( )在黄土中的迁移滞后现象应予以考虑。

The relative contributions of organic matter (OM) and CaCO 3 to the neptunium (V) sorption on loess were investigated by using the batch technique and the selective extraction methods of moderate concentrations (~10 -5 mol/L) and under aerobic conditions. The sorption and desorption isotherms on the untreated loess and the treated losses to remove organic matter, CaCO 3 and organic matter plus CaCO 3 were determined and analyzed with the Freundlich equation.The effects of adding the fulvic acid (FA) from the loess and the carbonate in solution on the sorption of neptunium on loess were studied too. It was found that the CaCO 3 is partly responsible to the sorption/desorption hysteresis and there is a negative contribution of CaCO 3 in the loess to the Np(Ⅴ) sorption; that the OM is not responsible to the sorption/desorption hysteresis and the relative contribution of OM to the Np(Ⅴ) sorption may be small; that the addition of FA or carbonate in the aqueous solution has a obvious positive effect on the Np(Ⅴ) sorption, that the sorption of Np(Ⅴ) on the loess is mainly determined by the clay minerals in this loess. The retardation of Np(Ⅴ) migration in loess can be expected to be considerable.