Transport of Solutes and Macromolecules through Reverse Osmosis and Nanofiltration Membranes

0332217海洋：这项研究的主要目的是阐明从中性小分子到大分子的各种水污染物通过反渗透和纳滤膜渗透的机制。选定的溶质和大分子是亚砷酸、阿特拉津(216道尔顿)、罗丹明WT(480道尔顿)和三个大肠杆菌噬菌体(fr、ms2、t4)，大小从19到80 nm不等。这份清单是在几个标准之间达成妥协的结果，其中包括选择当前感兴趣的水污染物和用于评估反渗透/纳滤膜性能的替代物、已知的被反渗透/纳滤膜拒绝的小溶质和大分子，以及可用相对简单的无干扰分析技术在多溶质样品中定量的化合物。该项目的工作范围旨在对水和各种类型的溶质通过反渗透膜和纳滤膜的渗透机制有一个基本的了解，包括阐明浓差极化现象在目标溶质和大分子的整体传输中的作用。为了实现这一目标，将进行渗透实验，以表征通过膜聚合物基质的吸附/扩散/解吸和通过膜纳米孔的平流对整体溶质/大分子渗透的贡献，以及浓差极化对这两种类型渗透的影响。正在考虑的实验变量包括液压、背景和目标溶质浓度、温度和pH。然后，用原子力和扫描电子显微镜相结合的方法以及气体吸附/脱附技术来表征反渗透膜和纳滤膜活性层中纳米孔的尺寸分布。预计表征反渗透/纳滤膜的孔径分布将需要结合这三种方法所获得的结果。这项研究的最终任务将是开发一个机理模型来描述水、溶质和大分子通过反渗透和纳滤膜的渗透。

0332217 Marinas The primary objective of this research is to elucidate the mechanisms by which water contaminants, ranging from small neutral molecules to large macromolecules, permeate through reverse osmosis and nanofiltration membranes. Selected solutes and macromolecules are arsenious acid, atrazine (216 Daltons), Rhodamine WT (480 Daltons), and three coliphages (fr, MS2, T4) ranging in size from 19 to 80 nm. This list resulted from a compromise among several criteria including the selection of water contaminants of current interest and surrogates used to assess the performance of RO/NF membranes, small solutes and macromolecules known to be poorly-rejected by some by RO/NF membranes, and compounds quantifiable in multi-solute samples with relatively simple interference-free analytical techniques. The scope of work of the project is designed to develop a fundamental understanding for the mechanisms responsible for the permeation of water and various types of solutes through RO and NF membranes including elucidating the role of the concentration polarization phenomenon in the overall transport of target solutes and macromolecules. In order to accomplish this goal, permeation experiments will be performed to characterize the contribution to overall solute/macromolecule permeation by sorption/diffusion/desorption through the membrane polymer matrix and advection through membrane nanopores, as well as the effect of concentration polarization on both types of permeation. Experimental variables under consideration include hydraulic pressure, background and target solute concentration, temperature, and pH. Then, the size distribution of nanopores in the active layers of RO and NF membranes will be characterized by a combination of atomic force and scanning electron microscopy, and gas adsorption/desorption techniques. It is anticipated that characterizing the pore size distribution of RO/NF membranes will require integrating the results obtained with these three methods. The final task of the study will be the development of a mechanistic model to represent the permeation of water, solutes and macromolecules through RO and NF membranes.