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Reconciling DLVO and non-DLVO Forces and Their Implications for Ion Rejection by a Polyamide Membrane
Langmuir ( IF 3.7 ) Pub Date : 2017-08-21 00:00:00 , DOI: 10.1021/acs.langmuir.7b02306 Yijue Diao 1 , Mengwei Han 1 , Josue A. Lopez-Berganza 1 , Lauren Valentino 1 , Benito Marinas 1 , Rosa M. Espinosa-Marzal 1
Langmuir ( IF 3.7 ) Pub Date : 2017-08-21 00:00:00 , DOI: 10.1021/acs.langmuir.7b02306 Yijue Diao 1 , Mengwei Han 1 , Josue A. Lopez-Berganza 1 , Lauren Valentino 1 , Benito Marinas 1 , Rosa M. Espinosa-Marzal 1
Affiliation
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Recognizing the significance of surface interactions for ion rejection and membrane fouling in nanofiltration, we revise the theories of DLVO (named after Derjaguin, Landau, Verwey, and Overbeek) and non-DLVO forces in the context of polyamide active layers. Using an atomic force microscope, surface forces between polyamide active layers and a micrometer-large and smooth silica colloid were measured in electrolyte solutions of representative monovalent and divalent ions. While the analysis of DLVO forces, accounting for surface roughness, provides how surface charge of the active layer changes with electrolyte concentration, scrutiny of non-DLVO hydration forces gives molecular insight into the composition of the membrane-solution interface. Importantly, we report an expansion of the diffuse layer at high ionic strength, consistent with the recent development of the electrical double layer theory, but in contrast to the widely accepted phenomenon of aggregation in the secondary minimum. Further, the enhanced repulsion acting on modified membranes via polyelectrolyte adsorption can be quantitatively predicted by DLVO and non-DLVO forces. This work serves to solve past misunderstandings about the interaction forces acting on nanofiltration membranes, and it provides guidance for future work on the relation between surface properties and rejection mechanisms and fouling.
中文翻译：
调和DLVO和非DLVO力及其对聚酰胺膜离子排斥的影响
认识到在纳滤过程中表面相互作用对于离子排斥和膜污染的重要性，我们修订了在聚酰胺活性层中DLVO（以Derjaguin，Landau，Verwey和Overbeek的名字命名）和非DLVO力的理论。使用原子力显微镜，在代表性的一价和二价离子的电解质溶液中测量聚酰胺活性层与微米级且光滑的二氧化硅胶体之间的表面力。尽管对DLVO力的分析（考虑了表面粗糙度）提供了活性层的表面电荷随电解质浓度变化的方式，但仔细研究非DLVO的水合力可以使分子深入了解膜-溶液界面的组成。重要的是，我们报道了在高离子强度下扩散层的膨胀，与双电层理论的最新发展相一致，但是与次要极小值中被广泛接受的聚集现象相反。此外，可以通过DLVO和非DLVO力定量地预测经由聚电解质吸附作用在改性膜上的增强斥力。这项工作旨在解决过去对作用在纳滤膜上的相互作用力的误解，并为今后有关表面性质与排斥机理和结垢之间关系的研究提供指导。
更新日期：2017-08-22
中文翻译：
调和DLVO和非DLVO力及其对聚酰胺膜离子排斥的影响
认识到在纳滤过程中表面相互作用对于离子排斥和膜污染的重要性，我们修订了在聚酰胺活性层中DLVO（以Derjaguin，Landau，Verwey和Overbeek的名字命名）和非DLVO力的理论。使用原子力显微镜，在代表性的一价和二价离子的电解质溶液中测量聚酰胺活性层与微米级且光滑的二氧化硅胶体之间的表面力。尽管对DLVO力的分析（考虑了表面粗糙度）提供了活性层的表面电荷随电解质浓度变化的方式，但仔细研究非DLVO的水合力可以使分子深入了解膜-溶液界面的组成。重要的是，我们报道了在高离子强度下扩散层的膨胀，与双电层理论的最新发展相一致，但是与次要极小值中被广泛接受的聚集现象相反。此外，可以通过DLVO和非DLVO力定量地预测经由聚电解质吸附作用在改性膜上的增强斥力。这项工作旨在解决过去对作用在纳滤膜上的相互作用力的误解，并为今后有关表面性质与排斥机理和结垢之间关系的研究提供指导。
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