Comparison of chromatography and desiccant silica gels for the adsorption of metal ions—I. adsorption and kinetics
Comparison of chromatography and desiccant silica gels for the adsorption of metal ions—I. adsorption and kinetics
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DOI：
10.1016/s0043-1354(99)00017-2
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发表时间：
1999-09
期刊：
影响因子：
12.8
通讯作者：
H. Tran;F. Roddick;J. O’Donnell
中科院分区：
文献类型：
--
作者：
H. Tran;F. Roddick;J. O’Donnell
本研究比较了干燥剂硅胶（DSG）和色谱硅胶（CSG）去除溶液中Pb2+、Cu2+、Ni2+、Zn2+、Cd2+和UO22+等金属离子的能力。UO22+的平衡时间（小于1小时）短于重金属离子（2-3h）， DSG吸附达到平衡所需的时间较CSG长，这可能是由于其孔隙平均直径较小。对所研究的所有金属的吸附过程均表现为一级动力学。测定了每种金属的传质系数和总速率常数。DSG和CSG对金属离子的吸附率依次为UO22+>Pb2+>Cu2+>Zn2+>Ni2+>Cd2+。发现金属吸收量在两个pH单位范围内迅速增加。金属离子的吸附服从Langmuir等温线，优先顺序为UO22+>Pb2+>Cu2+>Ni2+>Zn2+>Cd2+。观察到DSG和CSG对单个金属的等温线相似，表明DSG的去除能力相当，并且可能作为CSG的替代品在吸附应用中使用。铅(II) -铀（VI）溶液的吸附表明，随着另一种金属浓度的增加，每种金属的吸收率都大大降低，铅（II）的吸附受铀（VI）的影响比对铀（VI）的影响更大，因为硅胶对铀（VI）的亲和力更高。
In this study desiccant silica gel (DSG) was compared with chromatography silica gel (CSG) for its ability to remove metal ions including Pb2+, Cu2+, Ni2+, Zn2+, Cd2+and UO22+from solution. The equilibration time was shorter for UO22+(less than 1h) than for the heavy metal ions (2–3h) and adsorption by DSG took longer to reach equilibrium compared with CSG, probably due to the smaller mean diameter of its pores. The adsorption process showed first order kinetics for all the metals studied. The mass transfer coefficients and overall rate constants were determined for each of the metals. The adsorption rates of the metal ions, in order of decreasing magnitude, were UO22+>Pb2+>Cu2+>Zn2+>Ni2+>Cd2+for both DSG and CSG. Metal uptake was found to increase rapidly within a two pH unit range characteristic for each metal. The adsorption of the metal ions obeyed the Langmuir isotherm and followed the preferential order UO22+>Pb2+>Cu2+>Ni2+>Zn2+>Cd2+. Similarity of the isotherms for the individual metals was observed for both DSG and CSG, indicating a comparable removal capacity of DSG and its possible use as an alternative to CSG in adsorption applications. Adsorption from lead(II)–uranium(VI) solutions showed that the uptake of each metal was considerably reduced with an increasing concentration of the other, the adsorption of lead(II) being more strongly influenced by uranium(VI) than vice versa due to the higher affinity of silica gel for the latter.