Membrane retention of herbicides from single and multi-solute media: The effect of ionic environment
Membrane retention of herbicides from single and multi-solute media: The effect of ionic environment
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DOI：
10.1016/j.memsci.2008.04.016
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发表时间：
2008-07
影响因子：
9.5
通讯作者：
K. Plakas;A. Karabelas
中科院分区：
文献类型：
--
作者：
K. Plakas;A. Karabelas
本文报道了三种商用NF/ULPRO膜在死端过滤模式下对三种除草剂在单溶质或多溶质给水中的保留情况的系统研究结果。通过控制钠、钙浓度，考察了离子环境对除草剂滞留率的影响。这些结果是根据除草剂和所用膜的特性来解释的。一般来说，粒径排除似乎是NF/ULPRO膜保留的主要机制，特别是在孔径与除草剂分子相似的膜的情况下。紧密的高脱盐膜表现出最好的保留性能。另一方面，相对松散的纳滤膜的截留效率也受到除草剂在膜上吸附的显著影响。与在单一化合物溶液中测定的结果相比，含有一种以上除草剂的饲料水的过滤结果不同（通常减少）。这是由于除草剂之间对吸附位点的竞争，这与膜表面性质直接相关。模拟真实条件（如地表水）的生理盐水过滤实验揭示了二价阳离子对除草剂滞留的显著影响，根据膜的类型，这种影响可能是正的，也可能是负的。然而，离子强度的影响，由于一价离子（NaCl），对除草剂保留似乎是相当小的。
Results are reported for a systematic study on retention of three selected herbicides, in single solute or multi-solute feed-waters, by three commercial NF/ULPRO membranes, using stirred cells in the dead-end filtration mode. The effect of ionic environment on the retention of herbicides is also examined by controlling sodium and calcium concentration. The results are interpreted on the basis of the characteristic properties of herbicides and membranes used. In general, size exclusion seems to be the dominant mechanism for retention by NF/ULPRO membranes, especially in the case of membranes with a pore size similar to that of herbicide molecules. Tight and thus high-desalting membranes exhibit the best retention performance. On the other hand, the retention efficiency of relatively loose nanofiltration membranes also appears to be significantly influenced by adsorption of herbicides on the membrane. Filtration of feed-waters with more than one herbicide present results in different retentions (usually reduced) compared to those determined in single compound solutions. This is attributed to the competition between the herbicides for adsorption sites, which is directly related to membrane surface properties. Filtration experiments with saline solutions, mimicking real conditions (e.g. surface water), reveal the significant effect of divalent cations on herbicide retention, which, depending on the membrane type, can be either positive or negative. However, the effect of ionic strength, due to monovalent ions (NaCl), on herbicides retention appears to be rather minor.