Sorption of organic cations onto silica surfaces over a wide concentration range of competing electrolytes.
Sorption of organic cations onto silica surfaces over a wide concentration range of competing electrolytes.
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DOI：
10.1016/j.jcis.2016.08.029
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发表时间：
2016-12
影响因子：
9.9
通讯作者：
Susann Kutzner;M. Schaffer;T. Licha;E. Worch;H. Börnick
中科院分区：
文献类型：
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作者：
Susann Kutzner;M. Schaffer;T. Licha;E. Worch;H. Börnick
对有机阳离子-固相相互作用的基本理解对于改善对广泛使用的物质（如药物化合物）在水生环境中的迁移和最终环境命运的预测是必不可少的。本文报道了用两种硅胶和天然含水层沉积物对两种阳离子模型化合物的吸附实验。对吸附剂进行了广泛的表征，并对不同背景电解质浓度下的表面滴定结果进行了讨论。为了检验竞争加剧对有机阳离子吸附的影响，在较宽的无机离子浓度范围（5个数量级）的批量实验中系统地研究了吸附的盐依赖性。有机阳离子的吸收遵循Freundlich等温线模型，并且由于潜在的阳离子交换过程，吸附容量随着电解质浓度的增加而降低。然而，在高离子强度（1 bbb10 1 M）下，吸附恢复相当大。据我们所知，这种效应以前没有观察到，似乎与吸附剂的特性和山梨酸结构无关。此外，吸附的恢复归因于特定的非离子相互作用，并且吸附系数与介质活度系数之间存在联系。最后，讨论了两种吸附剂吸附亲和力不同的原因。
The fundamental understanding of organic cation-solid phase interactions is essential for improved predictions of the transport and ultimate environmental fates of widely used substances (e.g., pharmaceutical compounds) in the aquatic environment. We report sorption experiments of two cationic model compounds using two silica gels and a natural aquifer sediment. The sorbents were extensively characterized and the results of surface titrations under various background electrolyte concentrations were discussed. The salt dependency of sorption was systematically studied in batch experiments over a wide concentration range (five orders of magnitude) of inorganic ions in order to examine the influence of increasing competition on the sorption of organic cations. The organic cation uptake followed the Freundlich isotherm model and the sorption capacity decreases with an increase in the electrolyte concentration due to the underlying cation exchange processes. However, the sorption recovers considerably at high ionic strength (I> 1 M). To our knowledge, this effect has not been observed before and appears to be independent from the sorbent characteristics and sorbate structure. Furthermore, the recovery of sorption was attributed to specific, non-ionic interactions and a connection between the sorption coefficient and activity coefficient of the medium is presumed. Eventually, the reasons for the differing sorption affinities of both sorbates are discussed.