【摘要】 用静态实验法研究了蛭石对重金属钴离子的吸附行为和机理,考察了平衡时间、pH、固体浓度、腐殖酸等水化学条件对吸附作用的影响。结果发现:Co(Ⅱ)在蛭石上的吸附在很短的时间里就可达到平衡。Co(Ⅱ)在蛭石上的吸附受体系pH影响很大,在酸性条件下,主要吸附机理是外层配合和离子交换,而在碱性条件下,主要的吸附机理是内层配合,腐殖酸对Co(Ⅱ)在蛭石上的吸附有一定的促进或抑制作用。在低pH下,腐殖酸在蛭石上吸附后形成了新的表面配合物而增强Co(Ⅱ)的吸附,而在高pH下,腐殖酸存在于吸附体系中,Co(Ⅱ)的吸附量明显小于Co(Ⅱ)/蛭石吸附体系。研究结果为环境中放射性核素的危害评估和有效治理提供了很好的参考。更多还原

【Abstract】 In this work,adsorption of radionuclide Co(Ⅱ) from aqueous solution onto vermiculite was investigated by using batch technique under various environmental conditions such as contact time,pH,solid content and humic acid(HA).The results indicated that the adsorption of Co(Ⅱ) onto vermiculite was very fast and the adsorption equilibrium can be obtained in a short time.Thus,the adsorption kinetic was well fitted by pseudo-second-order model.The results also indicated that the adsorption of Co(Ⅱ) onto vermiculite was strongly dependent on pH.At low pH value,the adsorption of Co(Ⅱ) was dominated by outer-sphere surface complexation and ion exchange with Na+/H+ on vermiculite surfaces,whereas inner-sphere surface complexation was the main adsorption mechanism at high pH value.Addition of HA increases Co(Ⅱ) adsorption at pH conditions below the adsorption edge observed in HA-free suspensions and diminishes Co(Ⅱ) adsorption at pH above the HA-free adsorption edge.The results are important for assessing the potential of practical application of vermiculite in Co(Ⅱ) and related radionuclide pollution management.更多还原