Zhang Muxue, Breitner Lauren, Howe Kerry J, Minakata Daisuke
Department of Civil and Environmental Engineering, Michigan Technological University 1400 Townsend Drive, Houghton Michigan 49931 USA
Department of Civil, Construction and Environmental Engineering, University of New Mexico, MSC01 1070 Albuquerque New Mexico 87131-1070 USA.
RSC Adv. 2020 Apr 21;10(26):15642-15649. doi: 10.1039/d0ra01966f. eCollection 2020 Apr 16.
Reverse osmosis (RO) is a membrane technology that separates dissolved species from water. RO has been applied for the removal of chemical contaminants from water and is employed in wastewater reclamation to provide an additional barrier to improve the removal of trace organic contaminants. The presence of a wide variety of influent chemical contaminants and the insufficient rejection of low molecular weight neutral chemicals by RO calls for the need to develop a comprehensive model that predicts the rejection of various chemicals in RO. Yet the role of the interaction between neutral organic compounds and a RO membrane, and how the functional groups of organic compounds affect the interaction have not been fully elucidated. In this study, we first constructed a molecular model for a reference polyamide (PA) membrane. We then investigated the impact of explicit water molecules and PA membrane functionality on the membrane structure using quantum mechanical calculations. We examined solvent-membrane interactions and then solvent-membrane-solute interactions using two neutral test solutes, arsenic and boron, by comparing the theoretically calculated aqueous-phase free energies of interaction with their experimental values. Finally, the validated PA membrane model was used to calculate the free energies of interaction for a wide variety of organic compounds such as haloalkanes, haloalkenes, alkylbenzenes and halobenzenes, which correlated with the experimentally obtained mass transfer coefficients. The correlation indicates that the interaction between organic compounds and PA membranes plays a critical role in the rejection mechanism.
反渗透（RO）是一种将溶解物质与水分离的膜技术。RO已被应用于去除水中的化学污染物，并用于废水回收，以提供额外的屏障，提高对微量有机污染物的去除效果。由于存在多种进水化学污染物，且RO对低分子量中性化学物质的截留率不足，因此需要开发一个综合模型来预测RO中各种化学物质的截留率。然而，中性有机化合物与RO膜之间相互作用的作用，以及有机化合物的官能团如何影响这种相互作用，尚未得到充分阐明。在本研究中，我们首先构建了一种参考聚酰胺（PA）膜的分子模型。然后，我们使用量子力学计算研究了明确的水分子和PA膜功能对膜结构的影响。我们通过比较理论计算的水相相互作用自由能与实验值，研究了两种中性测试溶质砷和硼的溶剂-膜相互作用，然后研究了溶剂-膜-溶质相互作用。最后，使用经过验证的PA膜模型计算了各种有机化合物（如卤代烷烃、卤代烯烃、烷基苯和卤代苯）的相互作用自由能，这些自由能与实验获得的传质系数相关。这种相关性表明，有机化合物与PA膜之间的相互作用在截留机制中起着关键作用。
